UC-NRLF . .* . v ' ' I ,- BIOLOGY LIBRARY V CATALOGUE REIGEN COLLECTION MAZATLAN MOLLUSCA, BRITISH MUSEUM. WAEEINGTON: PRINTED AT THE OBERLIN PRE33, BY P. P. CARPENTEK. 1855-7. ' PREFACE. THE Collection, from which the shells described in the following pages have been carefully selected, was made at Mazatlan, (lat. 23 1ST., long. 107 W.) during the years 1848-50, by a Belgian gentleman named Frederick Reigen. The bulk of it was sent to Liverpool for sale in 1851, and circumstances enabled me to make a searching examination of it. Dr. Gray having requested that the (comparatively) small selection which I had made for my own use should be deposited in the British Museum, I judged it conducive to the interests of science to obtain possession of the whole of the then-remaining stock, which was about to be dispersed ; and to select as many specimens as might be required (1) to illustrate the local-fauna of a known station at the mouth of the Gulf of California ; and (2) to exhibit the amount of variation, whether great or little, observed in comparing together large numbers of in- dividuals in the various species. The latter object appeared of no slight importance, especially for the sake of inland natural- ists ; who have usually to depend on the very limited number of specimens which are generally to be seen in public, still more so in private collections. The series of shells here enumerated is presented to the Trustees of the British Museum, and accepted by them, on the following conditions : (1) That it be preserved separate and intact, as a local collection : (2) That it be always open to the use of students, subject to the usual conditions: (3) That the donor be allowed to arrange the collection in its permanent place of abode : and (4) That a Descriptive Catalogue of it be printed under the direction of the Trustees. The collection consists of about 8873 specimens (2505 Bivalves, &c., and 6368 Univalves) mounted on 2529 glass tablets.* The number to the left refers to the species, that to the right to the * The following are the advantages of this mode of preserving specimens, either in public or private collections. (1) Both sides of the shell can -be seen ; thus combining the advantages of mounting vvith those of leaving loose. (2) The drawers or cases can be lined with any coloured paper that happens best to display the particular series. Very dark purple or black, glazed, will generally be found most suitable. (3) The tablets and shells can be cleaned as they stand, without remounting. (4) The tablets are extremely cheap, and can be rapidly cut to any required size. To write the names, white paint should be worked with a pestle in a little turpentine, till it is thin enough to pass through a fine steel pen. The strongest cement is common shell-lac dissolved in spirit; but the bleached liquid glue has a better appearance. The minute shells in the col- lection are cemented with Canada balsam to strips of thin glass, which are fastened into the corka of test tubes. 454925 IV. PREFACE tablet in the Catalogue, Of the minute specimens, magnified sketches are given, drawn under the microscope with Chevalier's prism-disc. The principal part of the money required for the purchase of the shells has been generously and without solici- tation provided by Herbert Thomas, Esq. of Bristol. For the remainder, and for all the work, from the first sorting and wash- ing to the permanent allocation, (including no inconsiderable ?=hare in the manual labour of printing,) I am alone responsible. The duty of writing the Catalogue was intrusted to me by Dr. Gray. I was ill fitted for it, (1) by almost entire ignorance of conchological literature, and (2) by living in a country town, with extremely limited access to scientific books and collections. There did not appear however any competent naturalist who possessed the absolute essentials of time and full access to the Mazatlan materials. I therefore undertook the task, trusting that its acknowledged deficiencies might in some measure be compensated-for by great patience and care in the faithful use of those means of information which were within my reach.* I have endeavoured to make it a companion to Prof. C. B. Ad- ams' extremely valuable Catalogue of the Shells of Panama, which belong to the same great Tropical Fauna of W. America. An estimate of the value of the Iteigen Collection as a geographical authority, and a comparison of it with other neighbouring faunas, will be found in the "Report of the pre- sent state of our knowledge of the Mollusca of the West Coast of N. America" presented to the British Association in Sept. 1856, and published in its transactions, pp. 159 et seq. The * In the course of the inquiry, I have met with the greatest kindness from naturalists, most of whom were previously unknown to me, but to whom I applied for assistance. To Hugh Cuming, Esq. I am under extraordinary obli- gations for his singular urbanity, in allowing the unrestricted use of his invalu- able collections, his library, and his original information to a complete stranger. Dr. A. A. Gould, of Boston, U. S. intrusted to my care, and to the perils of the Atlantic, the whole of his collections and notes from the W. American coast, for comparison with those known in this country. To Dr. Gray and R. M' Andrew, Esq. I am indebted for the long use of valuable works, and for advice and assist- ance throughout. Prof. Dr. Dunker, of Marburg, gave me valuable aid in the Mytilidae, J. D. Gaskoin, Esq. in the Cyprseadse and Columbellidse, L. Reeve, Esq. in the Patellidae, W. Clark, Esq. and W. Bean, Esq. in the Cajcidae, J ."Alder, Esq. in that family an^d in Jeffreysiadse, and Miss Steere in Olividse. S. Hanley, Esq. allowed me the use of his collection, (representing the Havre division of M. Reigen's stores,) and, along with R. D. Darbishire, Esq. Dr. Baird, Messrs. H. & A. Adams, Rev. T. Hincks, S. P. Woodward, Esq. and F. Archer, Esq. gave the benefit of critical judgment and experience whenever solicited. I am also under great obligations to the officers of various public museums and libraries, for the kindness with which they have attended to my requests. One whose promised aid would have been of invaluable service, and whose friendly encouragement mainly induced me to undertake the work, was, at its com- mencement, suddenly removed from the field of labour which was opening before him with such promise in the metropolitan university of Scotland. PREFACE V. only account of the shells of Mazatlan previously known, is Dr. Menke's list of the species brought by Mr. JL Melchers, published in the Zeitschriftfur Malacozoologie, 1847-51. An analysis of these is given in the Brit. Assoc. E,ep. pp. 235-239. The species of Bryozoa,* (now first, I believe, included in a catalogue of Mollusca, although generally acknowledged by naturalists to belong to that Subkingdom) have been described by G-. Busk, Esq. with his usual kindness. The class is named as in Dr. W. B. Carpenter's "Principles of Comparative Physi- ology, 1854." The name Polyzoa is believed to have precedence : but while the names of genera and species are proper names, and therefore ought to follow the law of priority, the arrange- ment of classes and orders is a matter of opinion ; and it appears allowable to make use of those names, whenever given, which best express the leading characteristics of the division. For this reason Palliolranckiata and Lamellibranchiata are used instead of the older names ConcJiifera and (or rather, including) BracMopoda ; Proboscidtfera for ZoopJiaga, &c. In the pre- sent case, when the name of a supposed order (of Polypes) becomes entitled to rank as a Class (of Molluscs), and as such has to be learned in common schools, it appeared very important to select a name that could not easily be confounded with others of similar sound. In the bivalves, the order of Prof. E. Forbes, adopted by Mr. Woodward in his invaluable "Manual of the Mollusca," has been mainly followed : in the univalves, that of Dr. Gray, who obligingly lent me the proof sheets of his " Systematic Arrangement of the Mollusca" now passing through the press. I am not possessed of sufficient knowledge of physiological anatomy to give an independent opinion on disputed points. Having found considerable difficulty in the identification of species, when Lamarckian genera are retained without division, although now as numerous and diversified in recorded forms as were many of the Linnsean genera in the days of Lamarck, I have freely adopted many of the generic names recently pro- posed, and have even, in some few cases, added to them. It is a matter of secondary importance, whether an accurately defined group takes rank as a mere section in a subgenus, or as a lead- ing division in a family : but the binomial designation is much easier for reference than that by sections. For ordinary purposes * The Crustacea, Cirripedes, Annelids, Kadiata, &c. found in the Eeigen Collection, are deposited in the Warrington Museum ; which has the honour of being the first Free Museum and Library established in the manufacturing dis- tricts. Duplicate series of the shells can be obtained through the Curator. VI. PEEFACE it may be sufficient to cite the lower division, the genus (like the family, &c.) being implied. "When the genus is required, it should have been always quoted, as it is in the later sheets, thus (Terebra) Myurella albocincta* In naming the genera and species, I have almost always followed (to the best of my knowledge) the law of priority, with the modifications authorized in the Brit. Assoc. Rep. 1842, pp. 109 et seq. In a few cases however, in which different forms have been described as distinct species, which I have thought it necessary to unite, I have chosen that name (irre- spective of priority) which represents the typical state of the species. By this means, those who are not satisfied with the union can keep the accustomed names for those forms which they regard as distinct, without adding to the confusion. Thus the name Dione chioncea of Menke is chosen, being applicable to the whole species, of which D. squalida, Sby., D. Uradiata, Gray, D. cliione Sby. (pars), and perhaps D. elegam, Koch, had been previously described from peculiar forms. To have dispensed with no fewer than 104 species constituted by naturalists of reputation (exclusive of synonyms), and at the game time burdened science with the names of 222 new ones, in a list numbering not quite 700 species, may seem extremely presumptuous in so inexperienced an author ; as also may the opinions freely expressed on various recorded statements. But fresh sources of information must always be expected to modify judgments formed from insufficient materials : and, as a natu- ralist should desire truth above all things, and wish to save others the necessity of wading through the same labyrinth of errors from which he has with difficulty extricated himself ; it appears a duty to lose no opportunity of correcting those state- ments in previous works which are liable to create confusion. The first person has been frequently used to shew that the statement put forth is not necessarily a fact, but simply my interpretation of a fact : and for a similar reason I have freely employed the mark of uncertainty [?] , which is to be under- stood as always referring to what follows, and not the word going before. Thus Bulla ?nebulosa, Grid, signifies that it is uncertain whether the Bulla belongs to Grould's species : while ?Alaba conica signifies that the generic position of the species conica is doubtful. * It would save much confusion if those wh:> divide genera would always make the subordinate names of the same gender with the original genus : also if authors, in describing new species in old genera, the modern divisions of which are not generally recognized, would avoid repeating a name already given, n another of the sectional groups. Vide Brit. Assoc. Hep. loc, cit. PEEFACB Vll . As the proposed object was to exhibit all that was known of a local fauna, many species are described from more or less imperfect materials, which would not have been noticed if from a mixed collection. The same course is usually followed in describing the fossils of any given formation, where obj ects are carefully noted that a mere collector of "good shells" would cast aside as worthless, There appears no reason for denying all knowledge of existing forms, merely because that knowledge is not as full as may be desired. In spite of the interests of classical Latinity being freely sacrificed, whenever those of brevity come into collision, the diagnoses of species will generally be regarded as much too long. The reasons are, (1) that I generally had to describe not single specimens, of which a literary picture could be drawn, but a large number, all whose observed differences had to be inclu- ded : and (2) that, in our present state of very limited know- ledge, it is necessary so to describe as not only to separate the object from previously known species, but from other similar ones that may be hereafter discovered. Those who have en- deavoured to identify critical species from the descriptions of some of the early naturalists, would willingly part with the acknowledged convenience of brief diagnoses for the sake of a greater approach to accuracy. When a fauna (like the British) has been well explored, a careful analysis of species may allow of their identification with but few words of separative descrip- tion. In many instances, the materials at command were not sufficiently clear to decide whether differences of form were of specific or only of varietal value. In these cases, they are generally tabulated as conspecific ; but with the ? variety separately named and described, ready afterwards to take rank as a species, or to merge into the related form, as further facts or better judgment may decide. The measurements (unless otherwise expressed) are, in obedi- ence to an authority, thus taken. In bivalves ; long, from the umbo to the middle of the ventral margin ; lat. from the anterior to the posterior ends ; alt. the thickness of the closed valves. In the spiral univalves ; long, from the vertex to the base ; long. spir. from the vertex to the posterior end of the labrum ; lat. the diameter of the body whirl ; div. the mean angle of divergence of the spire outlines. All the measure- ments of length are given in inches and decimal portions. In describing sculpture, (the words longitudinal and trans- verse not havingbeen always used in the same sense) the follow- ing terms have been generally employed. In the bivalves ; con- Till. PEEFACE centric, in the direction of layers of growth ; radiating, from the umbo to the margin. In the spiral univalves ; radiating (from the axis of the shell), in the direction of layers of growth ; spiral, along the whirl, paralle 1 to the suture. In comparing the words used to describe sculpture dirse, lirulse, striae, striulse, &c.) with the same words in other books, they should often be interpreted as to the appearance of the shell under the micro- Scope, generally with an inch-achromatic. The vertex applies to the whole nuclear portion ; but the apex only to the first whirl. As a slight twist in this may, or may not, be estimated as a whole turn, the number of whirls, as stated by different authors for the same shell, may sometimes vary.* In citing geographical authorities, the name of the first observer (not necessarily the collector) is distinguished by Italics, in preference to the mark [!] now frequently used ; since it is not a matter of surprise, but of emphatic fact that a certain person brought a shell from a particular place. The S. W. Mexican collection, frequently quoted with my initials, was brought from a port on "that coast," probably Acapulco : vide Brit. Assoc. Rep. 1857, pp. 281-3. The terms expressing frequency are to be understood as applying to the collection when I first saw it, after several of the shells had been withdrawn by purchasers. They are to be interpreted relatively to the total number, and are generally used as follows : extremely rare, under a score ; very rare, under 100 ; rare, under 200 ; not common, or not uncommon, 300 ; com- mon, up to 400 or 500 ; abundant, about 600 or 700 ; extremely common, up to 1,000 ; extremely abundant, more than 1,000. The errors which arise from ignorance, those with better judgment and means of information will be able to correct. The errors of observation can easily be detected, as the shells themselves are open to all who desire to study them. It is hoped that all such errors will as speedily as possible be detect- ed and exposed ; and that this work may soon be laid aside as useless, having served its purpose as a stepping-stone to some- thing far better. The sooner our own work perishes, the truer will be our knowledge of Him whose exquisite order and beauty can be abundantly traced, even (as in the following pages) in the worm-eaten passages of a decaying shell. PHILIP P. CAKPEOTEE. Warrington : April 22nd, 1857. This may account for discrepancies in Vitrinella, and in the description* of the nuclear vertex in Pyramidellid, In this catalogue the number is o.ver rather than under-rated. CONTENTS. PAGE. CLASS BRYOZOA. (Species 1-13, 677-679.) ORDER IOTUNDIBULATA. SUBOBDEB CHEILOSTOMATA. MEMBBANIPOBID.E. (Tablets 1 13.) Membranipora ... ... 1 Lepralia ... ... 3,6,529 CELLEPOBIDJE (tablets 1416.) Cellepora ... ... 5, 6 SUBOEDEB CYCLOSTOMATA. TUBULIPOBID^:. Tubulipora ... ... 6 DISCOPOBADJE (Tablets 17, 680.) Defrancia ... ... 6 CLASS TUNICATA 7 CLASS PALLIOBRANCHIATA. (Species 14) DISCINID^B (Tablets 1820.) Discina ... ... 7 CLASS LAMELLIBRANCHIATA. (Species 15-220, 680691, 693, 694.) PHOLADIM. (Tablets 2142.) Pholadidea ... ... 8 Parapholas ... ... 9 . Martesia ... 13 G-ASTBOCH2ENID2E. (Tablets 4359.) Gastrochsena ... ... 14 } 547 SAXICAVID^E. (Tablets 6064.) Saxicava ... ... 16 PETBICOLIDJE. (Tablets 6574, 781, 2516.) Petricola ... ... 17,547 Hupellaria (Venerupis) 20 Naranio ... ... 169,529 MYID^. (Tablet 2517.) M ya ... ,,. 529 COBBUIIDJE. (Tablets 7582, 25182520.) Corbula ... ... 21,530,547 Sphsenia ... ... 24,530 X. CONTENTS (Lamellibranchiata, cont.) PAGE. PANDOKIDJE. (Tablets 8385, 2528.) Lyonsia ... 26,530,548 Tyleria ... ... 25,547 SOLECUETIDJE. (Tablets 8690.) Solecurtus- ... ... 27 TELLINIDJE. (Tablets 92131, 2521.) Semele (Amphtdesma) ... 28, 548 Cumingia ... ... 29 Sanguinolaria ... 31, 548 TeUina ... ... 32,531 Tellidora ... ... 39,548 Strigilla* ... ... 39 DONACIDJE. (Tablets 132210.) Iphigenia (Capsa) ... 42, 548 Donax ... ... 43,548 MACTBIDJE. (Tablets 211215.) Mactra ... ... 50,548 Spisula ... ... 51 Mulinia ... ... 52,549 Gnathodon (Bangia) ... 52, 549 VENEKIDJE. (Tablets 216411.) dementia ... ... 54 Trigona ... ... 54,549 Dosinia (Artemis) ... 60 Cyclina ... ... 62 Dione ... ... 63 Cytherea ... ... 70 Venus (CMone) ... ... 71,549 Tapes ... ... 76 Anomalocardia ... .... 78 ASTABTIM. (Tablets 412424.) Circe ... ... 81 Gkmldia ... ... 82,549 Cardita ... ...^ 84 Venericardia ... ... 85 Trapezium (Cypricardia) ... 86 CHAMIDJE. (Tablets 425445.) Chama ... ... 87,549 CAEDIADJE. (Tablets 446463, 2522.) Cardium ... ... 90,531 LUCINIDJE. (Tablets 464478. ) Lucina ... ... 96 Fimbria (Corbis) ... 101 CONTENTS x i. Lamellibranchiata, cont.) PAGE DIPLODONTIDJE. (Tablets 479484.) Diplodonta ... 102,549 Felania ... ... 103,549 KELLIAM. (Tablets 485504, 2523, 2529.) Kellia ... 105 La sea ... 107,531,549 Lepton HO Pythina . . . 112 Montacuta ... 112,531 CYCLADIDJE. (Tablets 505522.) Cyrena 114 UNIONIDJE. (Tablets 523 527.) Anodonta ... 117,550 MYTILIM. (Tablets 528607, 2530.) Mytilus 118 Septifer ... 12() Modiola ... ... 120 Crenella ... 123,550 Lithophagus (Lithodomus) ... 124 Leiosolenus 130,550 AKCAM. (Tablets 608666, 2524.) Area ... 132,532,550 J3yssoarca . . . 138 Pectunculus . . . 144 CULIDJE. (Tablets 667, 668.) JN"ucula . . . 145 Leda ... 145 AVICULIDJE. (Tablets 669690.) ffcna ... 146 Avicula ... 147 Margaritiphora (Meleagrina) 149,550 Isognomon (Perna) 149 PECTINID^:. (Tablets 691, 2525, 2526.) Pect en ... ... 152,532 SPONDYLIDJE. ( Tablets 692701.) Spondylus ... ... 152 Plicatula ... ... 155 OSTEEIDJE. (Tablets 702744.) . Ostrea - 156,550 ANOMIADJS. (Tablets 745 780.) Placunanomia . . . 164 Anomia . . . 16^ CLASS PTEROPODA. ... 170 Xii. CONTENTS FAG*!. CLASS GASTEROPODA. (Species 221-676, 692.) SUBCLASS OPISTHOBRANCHIATA. (Species 221-229, 692.) ORDER TECTIBRANCHIATA. C YLICHNIM. ( Tablets 782784.) Cylichna ... ... J70 Tornatina ... ... 171 BULLIES. Tablets 785793. Bulla ... ... 172 Haminea ... ... 174 PHILINIDJE. (Tablet 2527.) Smaragdinella (Glauconella) 533 SUBCLASS PULMONATA. (Species 230-241.) ORDER GEOPHILA. (Species 230-234.) TESTACELLIDJE. (Tablets 794, 795.) Grlandina ... ... 17U HELICIDJE. ( Tablets 796811.) Orthalicus (JBulimus) ... 176 ORDER LIMNOPHILA. (Species 235-238.) AuBicuLiDJE (Tablets 812814.) Melampug (Gonomlus) ... 178 LIMNEID2E. (Tablets 815832.) Aplexa (Physa) ... Planorbis ORDER THALASSOPHILA. (Species 239-241.) SiPHONAEiABvE. (Tablets 833867.) Siphonaria ... 181, 550 SUBCLASS PROSOBRANCHIATA. (Species 242-676.) ORDER HETEROPODA. (Species 242, 243.) IANTHINIM. (Tab lets 868 878.) lanthina ... 185,550 ORDER LATERIBRANCHIATA. (Species 244247.) DENTALIADJS. (Tablets 879-882.\ Dentalium ... ORDER SCUTIBRANCHIATA. (Species 248-329.) CHITONID^. (^5^5-883907.) Lophyrus Tonicia ... 193 Lepidopleurus Chiton Acanthocliites CONTENTS Xlll. (Gasteropoda ScutibrancMata, cont.) PAGE. PATELLIDJE. ( Tablets 908944.) Patella ... ... 199 Nacella ... ... 202 ACM2EID.E. (Tablets 9451016.) Acmsea (Tectura) ... 202,550,551 Scutellina ... ... 210 GADINIAM. (Tablets 10171023.) Gadinia ... ... 212 FISSUEELLIDJE. (Tablets 10241080.) Fissurella ... ... 213 Glyphis ... ... 220,551 Rimula ... ... 22'/, : TEOCHIDJE. (Tablets 10811180.) Callopoma (Turlo) ... 223 Phasianella ... ... 224 Bankivia ... ... 226 Uvanilla (Imperator) ... 227 Trochus ... ... 231,551 Omphalius ... ... 233,551 Yitrinella ... ... 236 PLiotia ... ... 248 Globulus (Eotella) ... 250 Ethalia ... ... 250 Teinostoma ... ... 253 JNEKITIDJE. (Tablets 11811312.) Nerita ... ... 255 Neritina ... ... 258,551 ORDER PECTINIBRANCHIATA. (Species 330-676.) SUBOEDEE ROSTRIFERA. (Species 330-^449.) VANICOEID^E. (Tablets 13131315.) Yanicoro (Narica) ... 262 CALYPTMIM. (Tablets 13161461.) Trochita ... ... 264 Galerus ... ... 265 Crepidula ... ... 267 Crucibulum ... ... 286 Calyptrasa ... ... 294 CAPULIM. (Tablets 14621475.) Hipponyx ... ... 296 Capulus ... ... 300 XIV. CONTENTS (Gasteropoda Hostrifera, cont.) PAGE. VERMETIM. (Tablets 14761513.) Siphonium .. ... 301 Aletes ... ... 301 Vermetus ... ... 303 Bivonia ... ... 305 Petaloconchus . . . 308 CJSCIDJE. (Tablets 1514 1551.) Caecum ... ... 312 TURRITELLIDJS. (Tablets 15521574.) Turritella ... ... 330,552 CERITHIADJE. (Tablets 15751^37.) Cerithium ... ... 333 Yertagus ... ... 339 Triforis ... ... 340 Cerithidea ... 342 LITORINIDJS. ( Tablets 16381703. ) Litorina ... ... 346 Modulus ... ... 351r$52 Fossarus ... ... 353 Isapis ... ... 355 KISSOID.E. (Tablets 17041715.) Bissoina ... ... 356 Barleeia ... ... 358,552 Alvania ... ... 359 Cingula ... ... 360 Hydrobia ... ... 360 JEFFREYSIADJE. (Tablets 17161720.) Jeffreysia (Rissoella) ... 361. TRUNCATELLID.E. (Tablet 1721.) Truncatella ... ... 364 PLANAXIDJE (Tablets 1722 1732.) Planaxis ... ... 364 Alaba ... ... ... 365 OVULIDJ2. (Tablet 1733.) Ovula (Radius) ... ... 370 CYPR^IDJE. (Tab lets 1734 1812.) * Cyprgea ... ... 371 Luponia ... ... 373 Aricia ... ... 373 Trivia ... ... 375 CANCELLARIAD^:. (Tablets 18131820.) Cancellaria ... 380 STROMBIDJE. (Tablets 18211827.) Strombus 381 CONTENTS xv (Gasteropoda Pectinibranckiata, cont.) PAGE SUBOBDEB TOXIPEEA. (Species 450-483.) TEREBEIDJE. (Tablets 18281878, 2515 ) Terebra ... 384 Myurella ... Q 84f ... Euryta ... ' 388 PLEUEOTOMIM. (Tablets 18791915 ) -Pleurotoma . qon T~4 *1V "" OtTU Drillia . Clathurella (Defrancia) - ... 400 Cithara ... . (Tablets 1916-1948.) Conus ... 401 SUBOKDEE PEOBOSCIDIEEEA. Species 484-676 AEiAD^:. (Tablets 1949, 1950 ) Torinia ... ... EAMIDELLID^. (Tablets 19512027 ) Obehscus ... 409 Odostomia ... 4^Q Auriculina Parthenia ... ... 4^3 Chrysallida ... 41 6 Chemnitzia ... ... 427 Dunkeria ... 433 Eulimella A i yjou CIS ... 437 Eulima ... ; ; t 43 8 Leiostraca OEEITHIOPSID^. (Tablets 20282035.) Oeritliiopsis .. 440 feCALAEiAD^. (Tablets 20362041.) Scalaria ... 44^ Cirsotrema 447 (Tablets 20422061.) - ... ... Lunatia ... 4^-^ Polinices ... ... 452 LIAMELLAEIADJE. (Tablets 2062, 2063.) -Lamellaria . . 4^0 ULID*;. Ficula ITONID^. (Tablets 2064-2072.) (Inton) Argobuccinum 454 XVI. CONTENTS (Gasteropoda Proboscidifera, cont.) PAGE. TURBINELLIDJE. (Tablets 20732078.) TurbineUa ... ... 456 FASCIOLARIAM. (Tablets 20792090.) Lathirus m ... ... [475] 457 Leucozonia ... ... [475] 457 Fasciolaria ... ... 458 MITRINJE. (Tablets 20912106.) Mitra ... ... 459 Strigatella ... ... 461 MABGINELLIDJE. (Tablets 21072109.) Marginella ... ... 461 OLIVIDJS. (Tablets 21102213.) Oliva 463 Olivella ... ... 467 Agaronia ... ... 472 PURPURID,E. ( Tablets 22142309.) Purpura ... ... 474 Cuma ... ... 481 (Rapana) Ehizocheilus 484 Yitularia ... ... 485 Nitidella ... ... 487 BUCCINIDJE. (Tablets 23102365.) Columbella ... ... 489 Metula ... ... 493 NASSIN^:. (Tablets 23662407.) Nassa ... ... 494 PYBTTLIM. ( Tablets 24082411.) Pyrula ... ... 500 MUEICID^E. (Tablets 2412 2514.) Fusus ... 502 Cominella ... ... 505 Anachis ... ... 505 Strombina . . . ... 513 Pisania ... ... 513 Murex ... ... 518 Phyllonotus ^. 521 Muricidea ... ... 526 CLASS CEPHALOPODA. APPENDIX. PHILIPPIC Descriptions of Mazatlan Shells MENKE'S First List and Descriptions of do. Second do. do. ADDITIONS and COBEECTIONS ... 546 CATALOGUE 01" MAZATLAN MOLLUSCA. CLASS BEYOZOA. Mr. BEYOZOA ; JZhrenberg, CoralL des Roth. Meeres, 153. Jones An. Kingd. 107 117. Owen Lect. 9310IA^ldomn fy Milne- JEdioards in Lam. An. s. Vert. ii. 104, 2de ed. Carpenter Princ. Comp. Phys. ed. iv. pp. 50 58. POLYZOA, J. V. Thompson, Zool. Res. Mem. v. 92. J. E. Gray in Si/n. B. M. 133. Johnstons Br. Zooph., i. p. 253, ed. 2 : v. note, p. 254. Busk in Ann. Nat. Hist. 2nd Ser. vol. 10. p. 362. MOLLUSCAN ZOOPHYTES s. ZOOPHYTA ASCIDIOIDA, Johnst. in Mag. Zool. fy Bot. i. 448. CILIOBBACHIATA, Farre in Phil. Trans. 1837. POLYPES TTJNICIENS, M. Edw. Mem. 16. ORDER I. BRYOZOA INFUNDIBULATA. P. G-ervais in Ann. des Sc. Nat. vii. 79. Johnst. Br. Zooph. i. 255. SUBORDER I. CHEILOSTOMATA. FAMILY MEMBEANIPOEIDJE. Membraniporidse, Bush, B. M. Cat. p. 55. GENUS MEMBEAMPOEA, Blainv. Menbranipora, Busk, B. M. Cat. p. 56. 1. MEMBRANIPOEA DENTICULATA, Busk, (n. s.) Areis cellularum rhomboideis ; apertura interiori inargine dentieulato. The outline of the cells is usually distinctly denned by a narrow brown line. One or two rounded or triangular eminences (probably ovicells,) are visible on many of the cells in front July, 1855. b Z MAZATLAN BRYOZOA and below. This form bears considerable resemblance to Mern- branipora Savartii (Savigny, Egypt, pi. 10; M. Lacroixii B. M. Cat. p. 60, pi. 104, fig. 1.) : but differs from it in several impor- tant respects ; among which may be noticed the narrow brown line surrounding the cells and clearly defining one from the other ; and the irregularly shaped branching denticles with which the margin of the interior calcareous aperture is fur- nished. Hah. Mazatlan ; on the shells of Imperator olivaceus, Imp. unguis and Anomia ; Liverpool Collection. Tablet 1 contains a group on Imperator. - 2. MEMBEANIPOEA GOTHICA, Rylands, ms. (n. s.) Areis cellularum elongatis, ovalibus ; margine glabro, tenui ; ore elevato, suborbiculari, inferne late sinuato ; cellularum superficie anteriori calcarea depressd, punctata, orificio magno utrinque perforato ; aviculariis magnis, immersis, irregulariter per polyzoarium sparsis. There is occasionally a short blunt spine or process on each side of the mouth, a character which also exists in M. Rozieri, Savigny, (B. M. Cat. p. 59, pi. 65, fig. 6,) a species to which the present exhibits in other respects considerable resemblance, and especially in the existence of the large opening on each side of the front of the cell immediately below the mouth. The differences between the two, however, are sufficiently striking. In M. Rozieri the ovicell is large, superior, rounded, and carinate in front ; whilst in M. gothica, as in M. calpensis, Husk, &c., this organ appears to be represented by one or two rounded eminences at the bottom of the cell in front. The large scat- tered avicularia also, are characteristic of the present form, as well as its much larger size. The same species occurs on a pearl-oyster shell, for which I am indebted to Dr. J. E. Gray ; the habitat assigned to which is doubtfully given as the Persian Gulf. In M. M. Edwards' Memoir Sur les JEsckares, p. 17, pi. 12, fig. 13, a miocene fossil is described and figured, which bears considerable resemblance to the present ; it differs principally, so far as can be determined from the figure alone, in the thickened and granulated margin of the area. Hob Mazatlan : on Imperator olivaceus and unguis ; L'pool Col. Tablet 2 contains a group on Imperator, 3, a group detached. MAZATLAN BEYOZOA GENUS LEPKALIA, Johnston. Lepralia, B. M. Cat. p. 63. 4 3. LEPEALIA ATEOFUSCA, Rylands, ms. (n. s.) Cellulis elongatis, ovatis seu rhomboideis, lined tenui elevatd cinctis, superfine punctalo ; ore sub orbicular i, inferne sinuato, utrinque denticulato. G-eiieral hue, blackish ; aud even when the cells are more calcareous and on that account whiter, the dark interstitial line remains very evident. It is quite distinct from L. cucullata, (B. M. Cat. p. 81, pi. 96, fig. 4, 5,) also of a black colour, and which occurs in the Mediterranean. Hob. Mazatlan ; on Imperator olivaceus and unguis, and on Anomia ; L'pool Col. Tablet 4 contains 2 groups detached. 4. LEPEALIA TEISPINOSA, Johnst. B. M. Cat. p. 70, pi. 85 ; fig. 1, 2 ; pi. 98 ; pi. 102. fig. 2.- Johns. Br. Zooph. i. 324, ed. 2 ; pi. 57, f. 7 '.Couch Corn. Faun. iii. 118. J. Macgillivray in Ann. fy Mag. N. Hist. ix. 467. Discopora trispinosa, Johns, in JEd. Phil. Journ. xiii. 322. Berenicea trispinosa, Johns, in Trans. Newc. Soc. ii. 268. A single minute specimen only has occurred to my notice, but this is quite indistinguishable from the British form. Hob. On shells from deep water, rare, Berwick Bay, Johnston. Coast of Cornwall, Peach. On root of Laminaria digitata, near Aberdeen, Macgillivray. Mazatlan ; on Imperator ; L'pool Col. Tablet 5 contains the group. 5. LEPEALIA MAZATLANICA, Busk. (n. s.) Cellulis immersis, depressis, seu ventricoso-globosis ; superficie punctato ; ore suborbiculari inferne late sinuato ; margine incras- sato, elevato ; aviculario unico (vel rare, duobus) later ali pr ope os. This form might easily be confounded with some varieties of L. unicornis, or L. Ballii. It is distinguished, however, by its reddish colour, and the elevation of the mouth together with its thickened margin. The single or sometimes double avicu- larium points outwards and upwards, and the mandible is pro- longed and acute. It is sometimes, but not frequently absent. Sab. Mazatlan ; on Imp. olivaceus and unguis ; L'pool Col. Tablet 6 contains a group on Imperator. 7, one detached. 4 MAZATLAN BRYOZOA 6. LEPEALIA EOSTBATA, Busk, (n. s.) Cellulis immersis, superficie tuberculatd sen, granulatd ; ore immerso, margine superiori Inconspicuo ; margine inferiori pro- funde sulcato ; aviculario magno, sessili, armato. The lower or interior margin of the mouth in the fully formed cells, is deeply grooved in the middle ; and on one side of the sulcus is a strong, short, blunt, spinous process ; on the other a comparatively large raised avicularium, which faces towards the sulcus, and whose mandible is acute and points upwards and outwards. The surface of the cell is often beset with short raised spines or processes ; and these, projecting over the mouth of the cell below, give it the appearance of being furnished with several oral spines. Hal. Mazatlan ; on Imperator unguis ; L'pool Col. Tablet 8 contains a group on Imperator. 9, one on base of do. 7. LEPEALIA MARGINIPOEA, JReuss. Fossil Polyp, d. Wiener Tertiar. Beck. p. 88, pi. 10, fig. 23. Cellulis ovatis, convexis seu subdepressis, immersis, asperulis, margine punctatis ; ore rotundo seu subelliptico ; margine sub- incrassato, singulo latere avicularium gerente. As the form appears precisely to resemble the tertiary species described and figured by Heuss, I have applied his name, and in great part employed his character. Hab. Mazatlan ; on Imperator unguis ; L'pool Col. Fossil, Vienna. Tablet 10 contains a group on Imperator. 8. LEPEALIA HIPPOCEEPIS, Bush, (n. s.) Cellulis immersis, superjicie punctatis ; ore suborbioulari seu elliptico ; margine superiori cellularum natu majofum, inconspi- cuo, inferiori et later all incrassato utrinque aviculanum gerente. The peculiarly horse-shoe shaped mouth of the older cells, sufficiently distinguishes the present from the preceding species, to which, in the mouth alone of the younger cells, it bears some resemblance. Hob. Mazatlan ; on Imperator olivaceus ; L'pool Col. Tablet 11 contains a group on Imperator. MAZATLAN BRYOZOA 5 9. LEPRALIA HUMILIS, Busk, (n. s.) Cellulis immersis, depressis sen complanatis, superficie obscure punctatis ; ore parvo rotundato, inferne subsinuato ; margine simplici, tenui. Hob. Mazatlan ; on Imperator unguis ; L'pool Col. Tablet 12 contains a group on Imperator. 10. LEPRALIA ADPRESSA, Busk. Busk in B M. Cat. p. 82. The Mazatlan form differs from that from Chiloe in the absence or indistinctness of the radiating grooves. The mouth and shape of the cell agree perfectly. Hob. Chiloe, 96 fm. on shell, Damvin. Mazatlan ; on Colum- bella major, C. fuscata, and Pisania gemmata, not uncommon ; L'pool Col. Tablet 13 contains a group on Columbella. FAMILY II. CELLEPOBILm Busk, B. M. Cat. p. 85. GENUS CELLEPOEA, 0. Fabr. Busk, B. M. Cat. p. 85. 11. CELLEPORA PAPILL^FORMIS, Busk, (n. s.) Cellulis sub-Jiexagonis, elevatis, superficie punctato ; ore sub- rotundato utrinque denticulato ; margine simplici, tenui, avicu- lariis sparsis, mandibulo triangulari. A well marked and distinct form, belonging to that subdivision of Cellepora in which the mouth is not armed with a projecting avicularium. The top of each cell projects in the form of a rounded mamillary eminence from a hexagonal area which defines the border of the cell. The cells are of very unequal sizes, and very irregularly disposed. It is of a brownish colour. Hab. Mazatlan ; on Imperator olivaceus ; L'pool Col. Tablet 14 contains a group on Imperator. ^12. CELLEPORA CYCLOSTOMA, Busk. (n. s.) Cellulis suberectis, seu decumbentibus, discretis, superficie punctato ; ore magno superne rotundato, inferne late sinuato ; cellularum natu majorum m&rgine valde elevato, incrassato, sub- inde dilatato, infundibuliformi, utrinque aviciilarium parvum gerente. *> MAZATLAN BRYOZOA The wide, rounded or elliptical raised margin of the mouths of the distant cells gives the polyzoarium of the present species a very peculiar and well market aspect. It is of a brownish hue, or white. Sab. Mazatlan ; on Imperator uuguis ; L'pool Col. Tablet 15 contains a group on Imperator. 16, a group de- tached. SUBORDER II. CYCLOSTOMATA. FAMILY DISCOPORAD^E. Busk, fmsj GENUS DEFRANCIA, Bronn. 13. DEFRANCIA INTRICATA, Busk, (n. s.) Disco valde irregulari ; irreg-ulariter radiatim costulato ; ori- ficiis tubulorum, porisque inter stitialibus cequalibus magnitudine. Tlie small irregular patches appear to be constituted by the confluence of several sets of costse with their corresponding interstices, each set radiating from a depressed central point. It differs from D. deformis Reuss, (L. c. p. 36, pi. 5, f. 24,) in the uniform size of the openings of the tubes in the costse and of the pores in the insterstices. Hob. Mazatlan ; on Imperator unguis ; L'pool Col. Tablet 17 contains a group on Imperator. Besides the above, there occur on some of the shells, indica- tions of other species, but in too imperfect a condition to allow of their determination. Among these perhaps the best marked is a species strongly resembling Cellepora pumicosa, Lin., a species of Lepralia, and of Tubulipora. CLASS TUNICATA. Omnia adhuc ignota. MA2ATLAN BIVALVES 7 CLASS PALLIOBRANCHIATA, Blainv. Brachiopoda, Cuv. Brachiopoda and Rudista (pars) Lam. Palliobranchiata, Blainv. FAMILY DISCINTD^S. GENUS DISCINA, Lam. Discina, Lam. Orbicula, Sow. not Cuv. or Lam. -$* 14. DISCINA CUMIN an, Brod. Orbicula Cumingii, Brod. in Proc. Zool. Soc. 1833, p. 125. Brod. in Trans. Zool. Soc. i. 143, pi. 23. f. I Mull. Syn. Test. Viv. p. 175. Lam. An. sans Vert. Desk. ed. tert. iii. pt. i. p. 118. no. 3. Sow. Thes. Conch, p. 366. no. 4. pi. 73. f. 6 D'Orb. Voy. Amer. Merid. Moll. p. 677. B. M. Cat. of D'Orb. Shells, no. 786, p. 89. Discina Cumingii, Davidsons Class, of Brack, in Brit. Fos. Brack, vol. i. p. 129. Tliis shell is the Pacific analogue of D. striata, which pro- bably belongs to the Atlantic. Some specimens of each species are hard to distinguish from the other. D. Cumingii varies greatly in form, according to the place of its attachment, and is often extremely thin, and scarcely shelly. This is always the case with the lower valve, which has its disk of attachment subtsrmirial, covered with a thin skin except at a very small chink. The upper valve is generally smooth near the apex, which is occasionally subcentral, afterwards closely set with radiating striae, more or less developed, and generally (not always) decussated by slightly raised lines of growth. Some- times nearly the whole of the upper valve is smooth and thin, as in Isevis. The lower valve generally displays only the con- centric lines of growth, but is occasionally decussated near the edge. It is sometimes so convex as to allow scarcely any space for the animal. Muscular impressions not so strongly marked as in D. striata. The young shells are often fringed round the edge, (with the remains of the cilia, Brod.) Colour, brownish yellow. The largest valve measures, ?o^. '4tf,alt. 'OS in. Hob. Payta (Peru), St. Elena, Panama, attached to lower sides of stones in sandy mud at low water 6 fm. : Cuming. Payta, Ecuador, St. Elena, D' Orbigny Seas of Chili [?] 'and Peru, Deshayes. Panama, common, under stones at low water, C. B. Adams. Mazatlan ; on Ostrea iridescens and Virginica, Chama% Pinnse, Spondylus Lamarckii, Strombus galea, in um- bilical chink of Yitularia salebrosa ; rare, L'pool Sf Havre Coll. MAZATLAN BIVALVES Tablet 18 contains 8 valves, very young, in test tube. Tablet 19 contains 4 adult valves. Tablet 20 contains Ostrea Virginica, with Chama Pspinosa attached, and 3 fine specimens of D. Cumingii in situ. One is removed from its nestling place be- tween the Chama and Oyster, and laid open to shew the inside. CLASS LAMELLIBRANCHIATA, Blainv. Conchifera : Lam. Phil. Zool. 1809 ; An s. Vert. v. 411, ed. 2, vi. 1. aray, Syn. B. M. 1840, 1842, p. 72 ; Proc. Zool. Soc. 1848, p. 183. Acephala Lamellibranchiata : Rang, Man. Moll. 272. Forbes and Hani. Br. Mol i. 55. Clark, Moll. Test. Mar. Br. 23. FAMILY PHOLADZD^E. Pholadidse, Gray, P. Z. S. GENUS PHOLADIDEA, Turt. Pholas, Lin. Lam. 15. PHOLADIDEA MELANUEA, Sow. Pholas melanura, Proc. Zool. Soc. 1834, p. 70. Sow. Thes. Conch. 1849, p. 499. .R M. Cat. D'Orl. Shells, no. 479, p. 56. This belongs to the same group of species as tridens, quadra, spathatula, and concamerata, which last represents it on the Californian coast. In its posterior cup-like appendages, it re- sembles Talona clausa from the Gambia. The shell is extremely thin, shewing inside a row of oblong tubercles impressed from without on the line separating the anterior and posterior por- tions, as well as the anterior ridges. These are closely set, strong, and waving ; and passing over the medial depression at an angle slightly widening as the shell becomes adult, are continued, concentric and straight, 'gradually fading as they approach the posterior extremity. This is covered with a thick epidermis, ending in a short double cup, which is bi-lobed outside and simple within. The adult closing of the valves is carried in a flat expansion round to the umbos. The largest specimen measures, with the cup, long. '9, lat. 1*85, alt. 8 '6. Hob. In hard clay and loose stones at low water, Monte Christi (Guayaquil), Owming. Ecuador, Monte Christi, D'OMgny. Mazatlan ; in company with P. acuminata, extremely rare ; Lpool Col. Tablet 21 contains the most characteristic (though a some- what imperfect) specimen. MAZATLAN BIVALVES 16. PHOLADIDEA PCURTA, Sow. Pholas curta, Proc. Zool. Soc. 1834, p. 71. B. M. Cat. D'Orb. Shells, no. 482, p. 56. The only two specimens found are too imperfect to identify with accuracy.. Though very small, they are both adult, and are known at once from the young of melanura by the extreme fineness of the anterior waved striae, the posterior part scarcely shewing more than lines of growth. Dorsal plate shield-shaped, in two layers, hollow within, rather large and regular. Long. '28, lot. '34; shield '17 by '15. Hah. Isle of Lions, Yeragua, in soft stone at low water, Cum- ing. Ecuador : Isle de los Leones, \f\If QrMfrn/y. Mazatlan, in Strombus galea, Havre Col. Tablet 22 contains 1 valve (the other being broken in extrac- tion) with its plate. GENUS PABAPHOLAS, Conr. Parapholas, Conrad, sp. This genus, including Calif ornica, Incii (Torres Str.), branchi- ata, calva, (acuminata,) and bisulcata (Woodw.) differs from Martesia (Leach) in having its cup laminae persistent and under- lapping one another. It further differs from Pholadidea in the large size of the umbonal plate, and the gaping in the ven- tral and dorsal margins, closed by plates in the adult shell. All yet known are from the Pacific. The Californian species is of large size, and makes a shelly tube for its siphons. 17. PAEAPHOLAS CALVA, Gray, ms. Pholas calva Sow. in Proc. Zool. Soc. 1834, p. Q$Thes. Conck. 1849, p. 493. Animal excavating a pear-shaped burrow in shell (or stone) which is perfectly smooth and circular transversely, so that the shell [(till it becomes adult) can move freely round in it. The orifice is subcircular, and rather large. As the animal continues its boring deeper, the swollen anterior portion becoming now posterior and therefore too large for the animal, which loves to have just room enough and no more, the vacant space is filled up with a lining (more or less thick according to the depth of the burrow) which is not an organic growth from the mantle, but appears to be nothing more than a sedimentary deposit in layers. Whether the burrow is in the purple or white portion of the Spondylus, the deposit is always dark grey. It may be detached as a tube from the cavity, and is often per- 10 MAZATLAN BIVALVES forated by other borers. The deposit is rarefy seen in young shells, but is common in adolescent and ? universal in old speci- mens. At the bottom of the burro ; v is generally seen an irregu- lar mark projecting beyond the smooth surface of the hole, formed by the Pfoot of the animal. Sometimes this is only a "scar, strongly resembling an irregular oval muscular impres- sion with an elevated marginal ridge from which it sinks back to a deep central linear depression, the whole strongly marked with concentric and radiating furrows." (Darbiskire) . More often there is a sort of side chamber, or shoe, irregularly exca- vated in the shelly matrix, and not always in the same relative position, the surface of which is warty and very irregularly corrugated. This is generally filled with a black horny sub- stance, giving an animal smell when burnt, but not displaying any silicious particles. In very old specimens this excavation is often enormously developed, occasionally reaching up be- tween the grey deposit and the shelly matrix. Even in rather young shells this foot-chink is sometimes seen ; and whenever the burrow reaches the inside of the Spondylus, the black substance is always first apparent. P Does the foot make this lodgment as a fulcrum, while the valves spin round and form the burrow : and after the adult valves can no longer move, Pdoes the foot amuse itself with forming these superfluous excavations. Shell, when extremely young, of xylophagoid shape, with the ventral portion undeveloped and the cup-laminse only existing as slight folds of the epidermis. Soon however two radiating lines become developed, and the ventral part rapidly increases. Throughout the younger portion of its life there is a very large dorsal as well as ventral gapa The anterior edge is marvelously thickened, ending in a stout knob, quite capable of aiding in bor- ing execution. In the single specimen found in a transition state, this knob is no longer prominent, and the anterior gape is par- tially filled with shell, not smooth as in the adult, but gradually carrying off the ribs of the thicker portion. Adult shell squarish or rounded anteriorly, short or length- ened, presenting all the intermediate forms between calva and acuminata of Sow. ; fitting so tightly into its burrow that when dried it is often impossible to remove it without fracture, the umbonal plate being firmly adherent to the matrix. The epider- mis is thin on the anterior part ; over the ventral part, folded in thick concentric layers, every 4 or 5 of which (varying in number) are as it were joined together along the posterior line into a series of tiles ; and thence continued in a series of over- MAZATLAN BIVALVES 11 lapping horny laminae over the posterior portion. The snout is nearly round outside, displaying the gaping ends of the valves within, and a bi-partite lamina, rather rugose, between the two. The margin is entirely closed (except at the anterior part) with thick horny epidermis, strengthened ventrally by a long narrow plate, not only filling up the gape of the young shell but projecting beyond the knob (now absorbed) into the anterior portion ; smooth, with a faint line in the middle : and dorsally by a thicker plate, with rather rounded projecting edges more or less swollen towards the umbos. These, with about a third of the surface of the valves, are covered with an irregularly shaped shield, smooth externally, encircling part of the dorsal plate, and with an internal, bi-partite, anterior lamina, fitting the valves. Between this shield and the hinge there is vacant room, but there appears no place of exit for the foot except at a very slight anterior chink, which seem to be all that the stretching power of the integuments can allow. The markings within vary considerably, the thick anterior ridge being often quite absorbed, and the hinge apophyses irregular. See a very full account of the animals of British Pholadidae, and the relations between lamellata and papyracea of Turton, in Clark's Moll. Test. Mar. Brit. p. 169212. The following are measures of different specimens : * Largest (acuminate) Long. '99 Lat. 1'93 Alt. .98 Shorter form '81 1'45 '78 SmaUest adult "35 '67 "34 SmaUestjun. '04 '06 ?*04 Hal. Adult in Spondyli, 12 fm., Isle of Perico in Panama Bay ; jun. in hard stones at low water, id. ;t Owning. Mazat- lan : abundant in Spondylus Lamarckii : also in ? primitive (not limestone) rock to which the Spondyli are attached ; 2 young specimens in Chamse, and 1 in Strombus galea : L'pool fy Havre Coll. Tablet 23 contains 8 valves very young. 24, 9 young speci- mens varying in size and acumination. 25, a young specimen with a part of its own burrow, in the tooth of a Spondylus, * In this family, and in Gastrochsenidse/the length was measured straight across, not to the middle of the central margin. t This is the accurate statement in the Proc. Z. S. : in the Thes. Conch., it is given as "collected by Mr. Cuming in very hard stone at low water in Panama Bay;" making it appear that all the specimens were thus collected, whereas the adults were found in Spondyli, 12 fm. deep. Similarly careless transcripts are not uncommon in the Monographs. 12 MAZATLAN BIVALVES shewing the grey lining and part of the pedal chink. 26, the adolescent specimen. 27, 6 adult specimens shewing various peculiarities of growth. 28, a sir all adult specimen in situ, with a thick irregular lining : another specimen remains en- tombed. 29, an adult with part of its burrow, shewing the stratified nature of the lining : the anterior portion of the shield curiously deformed. 30, a piece of Spondylus, with 3 young specimens in situ, and several burrows, shewing the stratified lining, and the pedal excavations reaching the inside of the shell, to the evident annoyance of the Spondylus, which has protected itself against one of its enemies by a protuberance *7 across, and '23 high. 31, a large piece of Spondylus with various burrows : a large one of calva, with enormous foot chink : a smaller one in the hinge tooth : two others with small foot marks : a burrow of PLithodomus encased from an old hole into which it had penetrated : a singularly twisted burrow of Gastrochsena, bent nearly double, &c. 32, fragments of the horny Pfoot. 33, fragments of the grey deposit. 34, fragments shewing hinge structure. 35, fragments illustrating the cup- laminse. 36, portions of the umbonal plate. 37, portions of the dorsal and ventral plates. - 18. PAEAPHOLAS ACUMINATA, Sow. Pholas acuminata, Proc. Zool. Soc. 1834, p. 70. Sow. TJies. Condi. 1849, p. 492. The author of this species distinguishes it from calva by the shape of the lamina? and posterior portion, which are variable in both forms ; and by the character of the umbonal shield. This last is the only constant character of difference. It is not only smaller, not projecting beyond the dorsal plate ; (which is not the result of age, being found in all the specimens ;) but, in all the specimens allowing of observation, it is turned-in all round, instead of at the anterior portion only as in calva. The external surface also is generally rougher, and the posterior gape smaller, not displaying the bipartite laminse so clearly. Still, as the shells exactly agree in all other respects, it is pro- bable that these differences only result from changes in situation. All the calvse were taken out of Spondylus : all the acumi- natse were sent loose ; and from their extremely perfect con- dition were probably extracted from clay or wood. If the latter, the irregularities of the decaying timber might cause the roughening of the plate-surface. The original specimens of acuminata however were taken out of argillaceous limestone. The largest specimen measures long. *8, lat. 1*54, alt. *77. MAZATLAN BIVALVES 13 Hob. Panama, in limestone rocks at low water, Cuming. Mazatlan ; not uncommon ; L'pool Col. Tablet 38 contains 3 normal specimens. 39, 3 do. distorted. 40, 2 do. shewing inside, and plates. GENUS MAETESIA, Leach. Differing from Pholadidea in the large development of the accessory plates ; from Parapholas in the cups not being per- sistent. 19. MAETESIA INTEECALATA, n. *-. M. t. parvd, subglobosd, in duas paries divisd ; parte anterior e tenuissime concentrice striatd, radiis longitudinalibus subobsoletis vix undatd ; in juniore maxime Jdante, margin? solido ; in adult A secretione semi-corned clous d : parte posticd subl&vi, epidermide copiose indutd, margine rotundato ; um- bonibus testa reflexd adhcerente ccelatis ; clypeo pyr\ iforme , parvo, solido, inter secretiones valvarum inter cal ante ; partibus ventrali et dorsali laminis semi-corneis, brevibus, a calyce repulsis ; calyce piano, brevi, simplici, extanle. The species is named from the remarkable way in which the umbonal shield pushes itself in anteriorly between the project- ing portions of the closed valves ; and in which the cup, which pouts out from the otherwise rounded extremity, pushes itself in between the anterior and posterior plates, cleaving them and thrusting them back. Mr. Haiiley was fortunate enough to find two specimens burrowing in Spondylus, of which the larger has not yet closed the anterior portion, but the smaller is adult. The .shield does not fold round the dorsal plate. The whole dorsal and posterior part has a thickened raised margin, pro- bably epidermal. The largest (adolescent) specimen measures long. '34, lat. '35, alt. *33. The cup in. the smaller specimen measures '06. Hab. Mazatlan ; in Spondylus Lamarckii, extremely rare ; Havre Col. Tablet 41 contains various magnified sketches of the two specimens in Mr. Hanley's collection. 20. . A curious little fragment, unfortunately too imperfect for identification, which may belong to a Pholad, but is certainly distinct from any of the foregoing. Shell with a strong, irre- Aug. 1855. c 14 MAZATLAN BIVALVES gularly curved tooth, deeply channeled on the convex side, appressed to the umbo and projecting considerably above the margin of the valve. No process on the hinge as in Pholas, and apparently with groove for external ligament. Outside oval, smooth near umbo, afterwards with slight concentric rounded ribs and very slight radiating furrows. Tablet 42 contains the fragment, and a magnified sketch. FAMILY GASTBOCHJENID^E. GENUS GASTROCHLENA, Spengler. *J- 21. GASTEOCH^NA TEUNCATA, Sow. Proc. Zool. Soc. 1834, p. 21. Animal excavating a smooth oval chamber at the end of a flattened narrow gallery, occasionally five times as long as the chamber itself.* The gallery is straight, variously bent, or even suddenly recurved at a considerable angle, according to circumstances. It is always lined with a shelly coat, not evidently different from the shelly matrix, but separable from it. The interior of the siphon gallery is more or less rugose, and towards the extremity is nearly bipartite. The presence of these creatures may always be detected by the 8 -shaped holes they make ; but there is no clue by which the probable place of their abode can be ascertained. When they make a sudden turn, in consequence of some knowledge of an approaching stranger even at a distance, they fill their discarded burrow with shelly lining. The English species has no objec- tion to burrowing through the graves of departed brethren, Carrying its tube across them: this was not noticed in any Mazatlan specimen. A ? foot mark is often observed opposite the anterior gape, but never so large as in Parapholas : occa- sionally in the adolescent shell, a chink is seen in a downward direction, filled with the black horny substance. The valves have free room to open widely in the cavity. The form varies, even in the young shell, and often, both in outline and markings, approaches ovata. It may be known at once however by the great peculiarity of the hinge ; in which the "small, spathulate lamina" which Forbes 8f Hani, have record- ed in their generic character, though scarcely observable in G. modiolina, assumes dimensions which almost entitle it and similar species to subgeneric rank. Umbos very near anterior gape : an indistinct diagonal line beyond which the concentric * Mr. Darbishire found one which measured 4' 5 in. exclusive of the cell. MAZATLAN BIVALVES 15 strise are coarser and more irregular. This (posterior) portion of the shell is covered with very copious epidermis, in wrinkled folds, as in Saxicava rugosa. Ligament long. The young shell has projecting umbos, and often serrated edges to the anterior gape. The largest specimen measures long. '57, lat. 1'17, alt. 57. The smallest valve, long. '02, lat. '05. Hob. In Spondyli, Isle of Perico, Panama, Cuming. Mazat- lan ; not uncommon in Spondylus Lamarckii, very rare in Chamse, Patella Mexicana, and in Imperator olivaceus and unguis ; Upool fy Havre Coll* Tablet 43 contains 6 valves very young, and 3 pairs adolescent. 44, Young specimen, piercing the apex of Imperator unguis. 45, do. Imp. olivaceus, with Bryozoa, &c. attached. 46. Young specimen in situ in Imp. olivaceus, with another younger, coter- minal. 47. Young specimen in Imp. olivaceus, with tube some- what projecting, which is unusual at Mazatlan. 48. 1. olivaceus broken across, and shewing 5 specimens of G. truncata, and one Lithodomus caudigerus, invading the Imperator's liver chamber. 49. Adolescent specimen in situ in fragment of Spondylus, with the tube laid bare, and the pedal chink and deposit. Also portions of several other tubes of Gastrochsena, Lithodomus and Petricola. 50, 3 adult specimens varying .in outline, of which one displays a pearl formed near the hinge, another a lamina cutting off a large part of the anterior end, as often happens in large aged fossil Saxicavse. 51. Fragment of Spondylus, displaying hole of G. truncata, which, having approached a Lithodomus too closely, has turned round, filling the vacant space with shelly matter. 52. Siphon pipe laid bare, by the decay of the worm-eaten Spondylus around : also bur- rows of Lithodomus plumula and Parapholas calva. 53, Pipes and thick lining of 3 Gastrochsense in Patella Mexicana : the two siphons in one are ail-but separated at the extremity. 54, 2 pipe-ends from Spondylus. 55, Fragments of shelly lining. 22. GASTBOCHJENA OVATA, Sow. Proc. Zool. Soc. 1834, p. 21. Burrow not differing perceptibly from that of G. truncata. Shell, when fresh, of a delicate lilac tinge, with sharp elegantly bent concentric ridges following the margin, closer at the an- * In the Bristol Institution is a Tablet marked G. cuneiformis, from the West Indies, Mr. Priske, containing 2 specimens ; of which one I was unable to separ- ate from G. ovata, the other (in its burrow) from G. truncata. Mr. Hanley states, from the examination of a collection made by M. Bean in Guadaloupe, and sent to him by M. Petit, that several species of borers are common to the two oceans. 16 MAZATLAN BIVALVES terior part. Epidermis not conspicuous. Lunular portion deeply impressed : umbos distant from mprgin. Hinge without spatli- ulate lamina : mantle marks rugose. More or less elongated, approaching sometimes the more ovate forms of truncata, especi- ally in the young shells, but distinguished at once by the hinge. The anterior margin in the young shells is generally serrated, like Pholas, more strongly than in truncata. Anterior por- tion either more or less than one-fifth of the entire length. The largest specimen measures long. '76, lat. 1*1, alt. 6 '2. Smallest, long. '04, lat. '08. Hob. Isle of Perico (Bay of Panama) and Isle of Plata, Cum- ing. Mazatlan ; in Spondjdus Lamarckii, very rare ; L'pool ^' Havre Coll. Tablet 56, 1 valve and 2 pairs very young. 57, young speci- men in situ. 58, 2 adult specimens ; one lilac, fresh ; the other white, large, dead. 59, fragments of shelly lining. FAMILY SAXICAVID.E. GENUS SAXICAVA, Sellevue. f 23. SAXICAVA AECTICA, Lin. (For the synonyms, both as to genus and species, of this Protean sheU, see B. M. Cat. frit. An. Part VII. pp. 8689.) ? = Saxicava solida, Soiv. Proc. Zool. Soc. 1834, p. 88: D'Orl. Voy. v. 521. ? = Saxicava Cordieri, Gould, ms. Mazatlan, Lieut. Green. This shell is named on the authority of R. M' Andrew, Esq. whose practical acquaintance with the forms it assumes both in Arctic and subtropical regions renders his opinion of weight. According to Hanley, Menke and Gould, it is a distinct species. I cannot separate some forms of it from solida. The creature seems to take delight in distorting itself, not thinking it neces- sary to lodge in an uneven cavity for that purpose. It seldom (if ever) bores, being found in cavities of Lithodornus &c. The young shells are just as variable as the old ones, sometimes assuming the characters of S. rugosa or the form of Sphsenia Binghami, but generally displaying the narrow, anteriorly trun- cate, bi-tuberculate character of S. arctica. It rarely takes the genuine Hiatella form. Ligament of variable length, generally rather short. Valves capable of opening widely, though rarely MAZATLAN BIVALVES 17 in a position to do so. Hinge teeth, 1 in each valve, rarely seen in adult. Largest specimen measures long. "63, lot. 1*17, alt. '47, A broad flat sp. '4, '68, '24, A long narrow one '3, '66, '2, Smallest '02, '04, '015. Hob. According to Forbes, Atlantic Ocean, Boreal Seas, Africa, China, Australia. Canaries, Webb fy Bert helot, B. M. Cat. Can. Moll. p. 22, no. 195. New Zealand, Capt. Stokes, B. M. 8. solida : Clefts of rocks, 18 fm. St. Elena, Cuming : Peru, Lima, Callao, D'Orligny, B. M. Cat. p. 58, no. 510. S. distorta, Say, Rhode Is. Jay. 8. Pholadis, Sea of Okotsk, Middendorf. Mazatlan ; in Spondylus Lamarckii, nestling in crevices and burrows, also in Chamee and Patella Mexicana, very rare adult, not common jun. ; L'pool fy Havre Coll. Fossil, Crag, &c. ; very large in the pleistocene beds at Ud- devalla, Sweden, E. D. D. Tablet 60, 6 young valves. 61, 1 valve and 6 pairs various ages and shapes. 62, 1 specimen bored into, and the valves cemented open by tube of borer : also 2 fragments to shew ligament. 63, A young specimen in hole of Lithodomus cau- digerus in Imperator unguis. 64, A specimen in situ in a Yer- metus, off back of Spondylus. FAMILY PETRICOLnm GENUS PETRICOLA, Lam. -f 24. PETRICOLA EOBUSTA, Sow. Proc. Zool. Soc. 1834, p. 4$ Sow. Thes. Condi, part xv. p. 775, no. 14 ; pi. clxvi. f. 16, Vl.Mwller, Syn. Moll. p. 229, no. 9. Philippi in Zeit. fur Malac. 1848, p. 163, no. 33, quasi sp. nov. : edidit Desk, in JB. M. Cat. Veneridce, &c. p. 210, no. 10. ? = P. bulbosa, Gould's plates, ms. The name of this shell, which was well described by Sow. in 1834, was appropriated by Philippi in his 3rd Century of new shells for a supposed new species ; which turns out fortunately to be a small specimen of Sow.'s species, and thus confusion of synonymy is unexpectedly avoided. Deshayes has unfortu- 18 MAZATLAN BIVALVES nately copied this description into his Cat. Ven. B. M., instead of the original one. The young is generally (so Phil.) "sub- globosa, alba," and occasionally shews the radiating ribs "pos- tice distantibus" ; the bifidity of the anterior tooth in the left valve is rarely seen in the adult. When extremely young, the shell is irregularly rugose, but not shagreened : the apex is then moderately prominent : the rugosities soon fall into regular ribs dividing between the posterior and ventral parts ; the interspaces are finely rugose. Very soon the apex disappears, and a large space round becomes eroded. The shell which has previously been white, assumes various shades of orange, lilac and chocolate, developing at last into a lustrous brown, especi- ally at the muscular impressions. Meanwhile the characteristic concave decussating strise appear between the ribs ; and on the posterior ribs (which are generally closer than the ventral but not so close as the anterior ones) are gathered up into knobs. The anterior ventral part is generally much swollen, often with a concave margin between that and the posterior end, which is not unfrequently much produced, flattened, and even bent up- wards. The short, semi-internal ligament (somewhat resembling Ungulina) is turned up spirally round the umbos, as inChamse, &c. The burrow is shaped as the shell, with a rising corresponding with its posterior ventral depression, and without any siphon gallery . The opening is oval, irregular, and always exposes to view the extremities of both valves. Mr. Darbishire has one fourth of a Spondylus valve, with no fewer than eleven Petricolse projecting their extremities. The interior of the burrow is irregular and rough. One of the Chamse, here- inafter enumerated, displays a Petricola, which, having bored through the Chama and come to the rock, preferred flat- tening its own valve to undertaking the unexpected labour. This creature, having no power to move round in its hole, is frequently bored into by its neighbours. A pedal scar is occa- sionally seen towards the anterior end, sometimes deep, with dried horny substance as in Parapholas. The largest specimen measures long. '87, lot. 1*22, alt. '73, The most oval " '63, '78, '52, The smallest '06, '08, '04. Hob. In rocks, 6 11 fm., Panama and Isle Muerte, Owning . Jim. in Avicula margaritifera, Panama, JE. B. Pkilippi. Mazatlan : in Spondylus Lamarkii, not uncommon : very rare in Chama. Very young shells are rarely met with ; MAZATLAN BIVALVES 19 perhaps from living near the outside, and therefore being easily washed out ; L'pool fy Havre Coll* Tablet 65, 4 young valves. 66, 2 pairs, 2 valves, adolescent. 67, 2 pairs, adult. 68, 2 pairs bored into and distorted. 69, specimens of dried foot. A burrow may be seen in ?36, and a specimen in situ among the Chamse. 25. PETRICOLA VENTRICOSA, DesJi. Proc. Zool. Soc. 1853, ?ubi. B. M. Cat. Yen. p. 214, no. 22. = (teste Sow.) P. denticulata, Sow. Proc. Zool. Soc., 1834, p. 46. Sow. Thes. Condi, part xv. p. 773, pi. clxvi. f. 6, 7. B. M. Cat. D'Orb. Moll. p. 64, no. 564 B. M. Cat. Yen., p. 213. no. 21. This shell agrees with the description of P. ventricosa better than with that of P. denticulata, and must rank with that species if they prove distinct. If they are identical, as Sow. supposes, his name, though not so expressive, has priority. It takes both the elongated and abbreviated forms. Long. '26, lat. '36, alt. '23. Hab. (P. denticulata) Payta (Peru) in hard clay and stones at low water, Cuming. Arica, D'Orbigny. (Var. abbreviata) Isle Plata, Cwming. Payta D'Orbigny. (P. ventricosa) Gulf of California, Mus. Cuming. Mazatlan : burrowing in Strombus galea, extremely rare, Havre Col. Received with other shells from the West Indies, P. P. C. Tablet 70 contains 2 opposite valves. 26. PETRICOLA , sp. ind. Tablet 71 contains a rugose fragment, apparently not identi- cal with any published species from the W. American coast. Hab. Mazatlan : in Spondylus Lamarckii : L'pool Col. * I strongly suspect that this species is also found on the W. African coast. I have a valve, received from the Bristol Institution where it had been before they had a single shell from the West Coast of America that I know of, and before Cuming's discoveries there. At that time there was plenty of trade between Bristol and Africa ; and I believe the species came out of Ostrea iridescens of which they had a large stock. Vide remarks on [that sp. and Placunanomia. If P. typica, Sow. Thes. Conch. No. 13. does not differ from robusta more than is there stated, it is probably the same species, from St. Thomas, W. Indies. 20 MAZATLAN BIVALVES GENUS EUPELLAEIA, Bellevue. Hupellaria, Fleuriau de Bellevue, 1802, Bullet. Soc. PMlom. nr. 62. Pkilippi, Handb. d. Conch, fy Mai. in loco. Gastrana, Sckum. 1817. Venerupis, Lam. ISlS.DesL B. M. Cat. Ven. p. 189. 27. RUPELLARIA LINGUA-FELIS, n. S. V. t. subcylindricd, albd, tenuissime et dense granulosd, sub- diaphand ; granulis irregulariter confertis, lineis radiantibus confluentibus ; circa umbones l&vigatd, liris concentricis inter- ruptd ; strias incrementi nonnunquam monstrante ; lunuld in- distinctd; umbonibus prominentibus ; intus politd, margine pland ; impressiones musculares vix monstrante, sinu pallii magno, circulari ; dentibus 3 2, quarum una bifida ; nympMs et liga- mento parvis ; dentibus et nympMs supra lineam cardinalem intus prominentibus. Shell in shape like P. mirabilis, Desk., which represents it on the Californian coast ; but recognized at once by its surface which presents, under the microscope, most delicate granula- tions somewhat like Tellina lingua-felis, whence its name. Smallest specimen measures long. '025, lat. '03, alt. '02, Largest 'H, *16, '09. Hab. Mazatlan ; in Chamse and Spondylus Lamarckii, nestling in burrows, rare ; L'pool fy Havre Coll. Tablet 72 contains 5 specimens in various stages of growth. 28. RTJPELLABIA EXAEATA, n. s. V. t. forma " Linguce-felis" simili, umbonibusque ut in specie Hid : sed radiatim tenue sulcatd, albicante, rufo-fulvo macu- latd : fortiori, nee intus politd : dentibus 3-3, quarum una bifida, extantibus : epidermide tenui, fused. Shell in size and shape like V. lingua-felis, but wanting the granulose texture, and covered (except at the umbos, which are concentrically striated) with very fine rather irregular radiating ribs, as in Petricola, interrupted occasionally by lines of growth. Colour whitish, stained with chocolate. Hinge teeth projecting upwards, not sideways as in the last. Pallial sinus large, well rounded. These shells have the general appearance of Naranio, Gray. MAZATLAN BIVALVES 21 Smallest specimen, long. '018, lat. *03, alt. '015, Largest '13, '21, '12. Hab Mazatlan ; a small colony were found nestled, and greatly incommoding each other, in empty Balani on Murex princeps : Havre Col. Tablet 73 contains 1 specimen in situ, in Balanus ; 3 others of different ages. 29. RUPELLAEIA , sp. ind. Tablet 74 contains a fragment resembling R. foliacea, Desl. Mazatlan ; with strong radiating ribs crossed by erect and beau- tifully undulated laminae. The sculpture smoothes off at the hinge margin. Hob. Mazatlan ; from the back of a Spondylus Lamarokii ; ISpool Col. FAMILY COEBULIB^. GENUS COKBULA, Brug. 30. COKBULA BICARINATA, Soiv. Proc. Zool. Soc. 1833, p. 35. Mull. Syn. Test. Viv. p. 229. Rve. Conch. Ic. 1844, pi. 3. f. 23. Hani, in Wood's Suppl. Ind. Test. pi. 12, f. 31. Hani. Descr. Cat. p. 46. B. M. C' Orb. The W. Indian analogue is L. plicata, Gray. Tablet 84 contains a perfect young specimen, just beginning its gape, and displaying the radiating strise ; also a fragment of an older one, shewing the hinge. 85, drawings of Mr. Archer's specimen, made by Master John Jackson. Another species of Lyonsia, allied to A. cuneata, Gray, has been brought from Mazatlan : but as all the fragments even, in the L'poolCoL, clearly belonged to L. picta, I have not ventured to include it. Like L. picta, it varies extremely in shape and gape : the latter being generally small, sometimes wanting. Texture smooth, extremely thin, white, glossy. MAZATLAN BIVALVES 27 FAMILY SOLECUETID^. GENUS SOLECTJKTUS, Blainv. 37. SOLECUETUS AFFINIS, 0. B. Ad. C. B. Ad. Pan. Shells, p. 300, no. 510. The author of this species does not point out wherein it dif- fers from its Atlantic analogue, S. Caribseus. The similarities are evident. The smallest specimen measures long. '3, lot. '84, alt. '14, The largest ' '77, 2'4, "48. Hah. Panama, very rare, C. B. Ad. Mazatlan : not common : L'pool Col. Tablet 86 contains 4 young specimens. 87, 3 adult. 88, 3, lighter colour. 89, 3 with thinner epidermis.* 38. SOLECUETUS POLITUS, n. s. S. t. forma " S. affini " simili, sed subtranslucidd, violaced, extus lined fused et lineis albicantibus nonnullis radiatd ; epider- _-....._.. ...... mide politissimd, fusco-rubente : iniusnymphiselontjatls, denticulis 1-2 acutis, sinupallii versus umbones maxime arcuato ; callositate ab umbonibus , lined fused exteriore con- veniente, subexpressd decur rente . Known at once by the brownish violet colour, glossy epider- mis, and dark ray corresponding with a slightly prominent ridge within. In this respect alone it resembles Machsera. In the pallial sinus, S. affinis is intermediate between politus and violascens : in colour, S. violascens is intermediate : in the pro- longation of the nymphse, S. politus. This species displays 2 small distinct muscular impressions between the umbo and the anterior adductor, which is oblong, but well defined : in S. vio- lascens, it tapers off irregularly, uniting with these two : in S. affinis it is irregular, not tapering, uniting with the others which are also irregular. The largest specimen measures long. '48, lot. 1'45, alt. '23. Hob. Mazatlan : 4 specimens found with affinis : ISpool Col. Tablet 90 contains the most characteristic specimen. * Lower down the coast was found a large specimen which appears a distinct species, and I therefore append a description, and deposit the shell in the B. M. SOLECUETFS VIOLASCENS. S. t. "S. affini" simili, sed majore, solida, violas- cente, rugis epidermidis tenuioribus ; nymphis elongatis, sinu pallii versus urn- bones minus arcuato. Long '95, lat. 3 '33, alt. -56. Sab. S. W. Mexico, P. P. C. MAZATLAN BIVALVES 39. ?SOLECUETUS , sp. ind. Tablet 91 contains a fragment very flat, white, thin* with irregular very fine striae, shewing within as well as without, Hal). Mazatlan : in Spondylus washings ; L'pool Col. FAMILY TELLINHLE. GTENUS SEMELE, jSckum. Syn. Amphidesma, Lam. 10, SEMELE PROXIMA, C. B. Ad. Amphidesma proximum, C. B. Ad. Pan. Shells, p. 289, no. 487. Amphidesma proxima, (sc. -urn) Eve. Condi. Ic. Amph. pi. 3, f.20. So much does this species vary in outline, and so closely do some forms approximate to S. elliptica, that it is still an open question whether C. B. Adams did right in separating it. The colour is typically orange within, and "the pallial portion is punctured. Hob. Panama, rare, C. B. Adams. Mazatlan ; common ; L'pool Col. Smallest specimen measures long. '04, lat. '05, alt. '02, Largest 2' 36, 2'5, 1'23, Transverse 2'03, 2'36, 117. Tablet 92 contains a pair and a valve, extremely young, which probably belong to this species, though there are lateral teeth slightly developed. 93, 5 specimens, normal state. 94, 5 speci- mens more oblong. 95, 3 specimens very regularly rounded. 96, 3 specimens, very transverse. 97, 4 young specimens, with very light epidermis. 98, 2 specimens shewing interior. 99, 2 pairs and a valve, deformed in growth, 41. SEMELE PVENUSTA, A. Adams. Proc. Zool. Soc. 1853, p. 96. Amphidesma venusta [sc.-um] Eve., Conch. Ic. Amph. sp. 3. pi. 1, f. 3. Tablet 100 contains a young valve which agrees in the main with this species. The concentric ridges are not developed, MAZATLAN BIVALVES 29 and here and there a few radiating striae appear tinder the microscope. Long. *28, lat. "34, alt. "13. Hab.W. Columbia, Mus. Cum. Mazatlan, 2 valves ; ISpool Col GENUS CUMINGIA, Sow. For amended generic character, v. Proc. Zool. Soc. 1850, p. 24. The shell differs essentially from Semele, in its lateral teeth and ligamental spoon. The animal also differs, as from Syndos- mya, in its irregular cryptophilic habits. The species here enumerated, are given under protest. Cumingise are nestlers, like Sphaenia and Saxicava, and therefore subject to every possi- ble variation of form. They are fond of growing in company, and squeeze each other up into the queerest shapes. And yet the published specific characters are mainly drawn from the shape alone, with th,e very variable markings. Almost all the species are variously ribbed concentrically, with minute radiat- ing decussations. The characters of the hinge may be more constant; but alas! neither Sow. nor A. Ad. even allude to them. I have examined about 60 specimens from Mazatlan which might easily be distributed into 20 species, with as good char- acters as those which distinguish Sow.'s species. C. B. Adams distributed his 14 specimens into 6 species, but mercifully for- bore to describe the 4 supposed new ones, on the ground that they are "probably somewhat variable." Locality also is no great help : the Atlantic and Pacific, the N. and S. Temperate species not differing from each other so much as each species may within itself. Mr. Cuming has most kindly come to my rescue, and named the principal specimens according to his types : the smaller ones, in which there is least distortion, I have mapped out as well as the microscope would allow me. To do the work satisfactorily would require a very large num- ber of individuals from various localities. The Mazatlan stock was large enough to confuse, not to help. 42.'CtTMINGIA LAMELLOSA, Sow. Proc. Zool. Soc. 1833, p. 34. Lavignon lamellosa, _R M. Cat. _D' Orb. Moll, p. 59, no. 518. Lamellae extremely irregular, sometimes scarcely shewing till the creature is nearly adult. Radiating striae not strongly marked. Pallial sinus moderate : hinge teeth moderate, pos- terior lateral tooth the longest. 30 MAZATLAN BIVALVES Smallest specimen measures long. '04, lat. '06, alt. '02. Largest 49, '72, '24. Tablet 101 contains 3 young valves. 102, the largest (imper- fect) specimen. 103, a C. lameJosa, which had established itself within the empty remains of a Petr. robusta, which had itself gone to dwell inside the skeleton of a deceased relative which had originally constructed the burrow.* The form coarctata was found by Mr. Hanley in Spondylus Lamarckii ; Havre Col. 43. ClTMINGIA TKIGONULABIS, Sow. Proc. Zool Soc. 1833, p. 35. Eve. Conch. Syst. pi. 49, f. 2. C. B. Ad. Pan. Shells, p. 288, no. 480. Lavignon trigonularis, Gray. B. M. Cat. I? Orb. Moll. p. 59, no. 519. Tolerably well distinguished by the great projection of the ligamental spoon and hinge teeth. The laterals are very short, truncated, and of nearly equal length. Pallial sinus very large. Decussating striae well developed. JST. B. The muscular scars often vary in shape with the distortions of the shell. The largest specimen found measures long. '5, lat. '62, all. "32. Hob. St. Elena : among stones in deep water, Cuming. Ecuador ; St. Elena, D" OMgny. Panama, very rare, C. B. Adams. Mazatlan : nestling in burrows in Spondylus Lam- arckii ; very rare ; L'pool fy Havre Coll. Tablet 104 contains 1 perfect and 3 broken specimens, of various ages. 44. CUMINGIA CALIFOENICA, Conr. Journ. Ac. Nat. Sc. Phil. 18 , p. Teeth andpallial sinus intermediate between C- lamellosa and C. trigonularis. Anterior side generally swollen. The largest specimen found measures long. '33, lat. '52, alt. '22. Hob. Upper California, Nuttall. Mazatlan ; nestling in bur- rows in Spondylus Lamarckii, very rare ; L'pool Col. Tablet 105 contains 1 young, and 2 adult specimens. * So I ha\e, in limestone from Weymouth Bay, Sphsenia Binghami nestling in the tube of a Gastrocheena modiolma which had been formed by soldering together portions of a Thracia distorta through which it had burrowed. MAZATLAN BIVALVES 31 45. CtJMiNGiA , sp. ind. Messrs. Cuming and Hanley who possess perfect specimens of this shell, regard it as a new speeies. Let those describe it however who understand the specific marks in this genus. The few valves found were all toothless. The pit and tooth marls are extremely small ; shell small, delicate, flat, triangular. It closely resembles C. striata, A. Ad. Proc. Zool. Soc. 1850, p. 25, and has affinities with Syndosmya tenuis. Long. '3, lat. '38, alt. '15. Hctb. California, Mus. Cuming. In Chamse, extremely rare ; Mazatlan ; Lpool fy Havre Coll. Tablet 106 contains 2 valves. Tablet 107 contains 1 of three small specimens which I can- not identify with existing species. The form is very regular, like C. Cleryi, A. Ad. but the shell is convex, and marked as in the typical species. The teeth bear most resemblance to C. Calif ornica, Conr. Long. '18, lat. '23, alt. "11. Hob. Mazatlan : in Spondylus Lamarckii, nestling in bur- rows : extremely rare ; Lpool Col. GENUS SANGUINOLAEIA, Lam. 46. SANGUINOLAEIA PUEPUEEA, Desk. Proc. Zool. Soc. 1854, p. 346, no. 137. Compare Sanguinolaria tellinoides, A. Adams in Proc. Zool. Soc, 1849, p. 170 : pi. 6, f. 6. ? = Tellina (non Strigilla) miniata, Gould's Plates, ms. This shell is extremely like S. tellinoides, but differs in texture, "one being thin and delicate, the other coarse and strong in comparison," Cuming. Gould's description may prove his shell to be different. It seems almost as much a Tellina as T.rufescens. It is the Pacific analogue of S. rosea. Only 2 specimens were found in the L'pool Col. (Mus. Archer & B. M.) ; but as several specimens were in the London shops, it is probable that more were sent in the Havre Col. Long. 1*07, lat. 1'73, alt. '47. Hob. Mazatlan : extremely rare ; L'pool Col. Tablet 108 contains 1 specimen. 32 MAZATLAN BIVALVES GENUS TELLINA, Lin. H( 47. TELLINA RUFESCENS, Cnemn. Ckemn. vi. p. 105. t. 11. f. 97Schroeter, Einl. t. 3, p. 5. no. 11. Dilw. Desc. Cat. vol. i. p. 85. Knorr, vol. vi. t. 12, f. 1. Hani, in Sow. Thes. Conch, vol. i. p. 307, pi. 63, f. 213. = T. operculata, Grmel. p. 3235, no. 32, Var. exc. Lam. ed. Desk. 1836, vol. 6, p. 192. Wood's Ind. Test. p. 19, no. 37. Hani. Descr. Cat. p, 62, t. 4, f. 37. =T. cruenta, Solander, ms. Portland Cat. p. 58, lot 1360. =T. opercularis Sow. Gen. no. 31, f. 1. Desk. Enc. Meth. vers t. 3, p. 1010, no. 9. This shell must not be confounded with T. rufescens of Grmel. which = Venus decussata, var ; nor with the too-similarly named T. rubescens of Hani., a shell found as far north as S. W. Mexico, (P. P. C.) but not yet obtained from Mazatlan. T. rufescens is known at once by its large size, red colour (often banded with whitish,) and greatly produced beak. Lower valve pro- jecting, as in Corbula, and displaying faint radiating lines, which are generally obsolete on the upper. It gapes at both ends, and nearly approaches Sanguinolaria. Long. 1*73, lot. 3*17, alt. '77. Hah. Coasts of Brazil, Humphreys. Caribbean Sea, Lam. "Cab. de M. Dufrene." (Indian Ocean, Wood.) Tumbez, (Peru,) in soft, sandy mud, 5 fm., Cuming. Mazatlan ; rare ; Upool fy Havre Coll. The authorities for the Atlantic Ocean do not appear satis- factory. On the other hand, the shell being known to the old writers is in favour of its having been brought from the West Indian seas. Tablet 109 contains 1 small specimen from the L'pool Col., and 1 large one from the Havre Col. in which it was less un- 48. TELLINA BEODEEIPII, Desk. ms. (teste Cum.} Compare Tellinides purpureus, Brod. fy Sotv. ZooL Journ. vol. iv. p. 363. Zool. Beech. Voy. p. 153, pi. 42. f. 2.= Tel- lina purpurascens, Hani. Descr. Cat. p. 74, suppl. pi. 9, f. 18 : do. in Sow. Thes. Conch, p. 295, no. 141, pi. 62, f. 194. MAZATLAN BIVALVES 33 Shell closely resembling T. purpurea ; from Real Llejos, Owning. It differs from the plate in Beech. Yoy. in having, the umbos less pointed and the teeth smaller. The surface is crowded with extremely close concentric stride, decussated (except on the fold area) by very fine radiating lines, which become obsolete, in one valve only, on the ventral portion. The fold area is nearly smooth (except lines of growth) on one valve ; 011 the other, with rather sharp raised ridges, carry ing on generally every other one of the concentric striae. Epideiv mis light brown, very thin, coarser on the fold area. The species much resembles (though smaller) T. priuceps, a valve of which was sent from S. W. Mexico, (P. P C.) It gapes on each side, and might almost pass for a Sanguinolaria, but for its flatness. Long. I 'IS, lat. 2*12, alt. '31. Sab. Mazatlan, 3 specimens (Mus. Archer, Darbishire, B. M.) Lpool Col. Tablet 110 contains one specimen. 49. TELLINA ?? MAZATLANICA, Desk, T. Mazatlandica, Proc. Zool. Soc. 1854, p. 359, Tablet 111 contains a minute fragment which may be the young of this species, though the characters of the hinge are somewhat different. The Cumingian type measures long. '79, lat. 1*3, alt. *32. Sab. Mazatlan ; Col. Cuming. ?? Do. in Spondylus washings, L'pool Col. 50. TELLINA DOMBEI, Hani. Proc. Zool. Soc. 1844, p. 144. Hani, in Sow. Tkes. Conch, p. 323. C. B. Ad. Pan. Shells, p. 282, no. 464. A plain, white, oblong shell, much swollen and produced anteriorly. Long. I'l, lat. 1*45, alt. '5. Hob Panama, in sandy mud, 12 fm. Cuming. Panama, rare, C. B. Ad. Mazatlan, 2 specimens, L'pool Col. Tablet 112 contains one specimen, 34 MAZATLAN BIVALVES 51. TELLINA FELIX, Hani. Proc. Zool. Soc. 1844, p. 11 Hani, in Sow. Thes. Conch, vol. i. p 281 : pi. 58, f. 52. C. B. Ad. Pan. Shells, p. 282. Closely resembling a West Indian species in form and colour : Hani, compares it with T. donacina. Long. '43, lat. *7, alt. "2. Hab. Sandy mud, 6 10 fm. Panama, Cnming. Panama, rare, C. B. Adams. Mazatlan : extremely rare, Upool Col. Tablet 113 contains 1 perfect valve. 52. TELLINA STEAMINEA, Desk. Proc. Zool. Soc. 1854, p. 363. One specimen was found, about two-thirds the size of the Cumingian type which measures long. '33, lat. .48, alt. '17. It is known from neighbouring species by the rounded very faint concentric striae, which are clearly displayed by the microscope near the umbo of the adult shell. J&h Gulf of California, Col. Cuming. Mazatlan, from Spon- dylus washing : Upool Col. Tablet 114 contain the specimen. 115 contains a minute valve and fragment which probably belong to the same, 53. TELLINA UONACILLA, n. s. T. t.jun. donaciformi, valde transversd, tenui, compressa, alba, concentrice liratd ; liris acutis, subceguidistantibus, alternis, medio scepe evanescentibus, antice rarioribus ; epidermide tenuis- sima, hue et illuc liras radiatim decussante ; postice valde products, subrotundatd ; antice angulatd, truncatd, brevissimd : marginibus ventrali dorsalique fere par allelis ; car dine dcntibus duobus quarum unus bifidus cardinalibus, laterali uno postico brevi appropinquante, extante. Helated apparently to T. donaciformis, Desh. f fa&m Torres Straits ; from which it is known at once by the strong projec- ting lateral tooth. The shape is so remarkably like a Donax, that I have only varied the termination from the British T. dona- cina. The specimen is young, but well characterized except in the inner surface, which does not display the muscular impres- sions. Long. '08, lat. "14, alt. *05. Hab. Mazatlan : off Spondylus Lamarckii, IS pool Col. Tablet 116 contains the only valve found. MAZATLAN BIVALVES 36 54. TELLINA PUNICEA, Born. 'Test. Mus. Gas. Vind. p. 33, pi. 2, f. 2. Dorset Cat, p. 30> pi. 7, f. 5. Linn. Trans, vol. 8, p. 50. Brit. Mar. Conch, p. 66. Brown Hlustr. Conch. Gr. Br. p. 100. Gmel. Syst. Nat. p. 3239. Wood, Ind. Conch, p. 20, no. til Dill. Descr. Oat. p. 90. Lam. ed. Desk, vol. 6, p. 196. Schroeler Einl. t. 3. p. 22, no. 79Des7i. Enc. Meth. vers. t. 3, p. 1011. no. 12. Hani, in Sow. Thes. Conch, vol. I/ p. 239, pi. 58, f. 89, and pi. 60, f. 154^. M. Cat. Moll. DOrb. p. 61, no. 433. Forbes fyHanl. Br. Moll. vol. 1, p. 314. =Donax Martinicensis, Lam. teste Gray. = Tellina alternata, Sow. teste Gray. = angulosa, Gmel. teste Desk. = sinmlans, C. B. Ad. Pan. Shells, p. 284. ?=striata, Chemn. Conch, t. 10, tab. 170, f. 1654-5 ; teste Dillioyn <$f Desk. : noil Forbes fy Hanley, Br. Moll., nee Hani, in Thes. The late respected and very accurate Prof. Adams made his T. sinmlans out of a valve he found of this species on what was (to him) the wrong coast. Unfortunately for his theory, the very slight differences he relied on (deeper furrows continued over the flexure, interspaces less flattened, and lateral teeth nearly obsolete) are not constant in the Pacific waters : and if one shell is common to the two oceans, which he is obliged to allow in the case of Crepidula unguiformis, why may not this be ? The shell is known at once by its regular Tellinides shape, solid texture, pink colour variously banded with white, and deeply channelled furrows, some of which generally coalesce on one side before they reach the flexure. The angle of the ligamental area is more or less developed : the passage of the sulcations over the fold varies not only in different specimens, but in the same shell, in the opposite valves, or from young to old. The closeness and flattening of the ribs, the colour and the size of the lateral teeth also vary considerably, though I have only had an opportunity of examining about 40 specimens. Long. 1*15, lat.1'9, alt. *47. Hab. [Coasts of Britain, Pulteney, Wood, &c] "A West Indian Shell, introduced into our Fauna through having been figured in the Dorset Catalogue as identical with striata Chemn." Forbes fy Hanley. Mediterranean, Lam. edDesh. Cuba, Sagra in B. M. Cat. p. 36 Brazils, D'Orb. in B. M. Cat. p. 61. St. Domingo, Sir. E. Schomberg, in B. M. Trinidad, Hani. This, like many other West Indian shells, 36 MAZATLAN BIVALVES has found its way into British and Mediterranaen lists with- out sufficient authority. T. striata, Chemn. ( angulosa, GmeL,=l8etaPult.=Don. Mar- tinicensis, Lam. = T. punicea, Turton, Dillw. &c.) hob. W. Indies Coasts of Guinea, and Rhode Island, U. S. ; Chemn. T. simulans, C. B. Ad. hob. Xipixapi in W. Columbia, sandy mud, 10 fm. ; Cuming. Panama (1 valve), C. S. Ad. Mazat- lan : very rare ; L'pool Col ; rare, Havre Col. Guayaquil, Hinds. Tablet 117 contains 2 pairs and 1 valve, shewing variations. 55. TELLINA ?CUMINGII, Hani. Proc. Zool. Soc. 1844, p. 59. Sow. Thes. Conch, vol. i. p. 223, pi. 58, f. 72. C. B. Ad, Pan. Shells, p. 281, no. 463. Tablet 118 contains 2 fragments which seem to present the colours and markings of this species. Hab. Guacomayo, in coral sand, Cuming. Panama, extremely rare, C. B. Adams. Mazatlan : fragments in shell washings, extremely rare ; L'pool Col. 56. TELLINA PEBUENEA, Hani. Proc. Zool. Soc. 1844, p. 61. Hani, in Sow. Thes. Conch, vol. i. p. 241, pi. 57, f. 91. Tablet 119 contains a fragment with deep sulci and^ stout ribs, which may belong to this species. Hab. Tumbez, (Peru,) in soft sandy mud, 5 fm., Cuming. ? Mazatlan: in Spondylus washings, IS pool Col. 57. ? TELLINA EEGULAEIS, n. s. ? T. t.jun. suborbiculari, convexiusculd ; margine ventrali sub- recto, umbonibus prominentibus ; diaphana, alba ; tenuissime et confertim cpncentrice liratd ; liris acutis, interstitiis aut lavibv* aut hue et illuc lineis radiantibus vix decussatis ; flexura nulld ; ligamento minimo ; cardine dentibus cardinalibus 3, paululum diver gentibus, lateralibus 2 distantibus, validis. An aberrant species, so regular in form that externally it would range better with Kellia. It wants the spoon-shaped MAZATLAN BIVALVES 37 process of Cumingia, but the ligament is scarcely apparent. Long. '06, lat. '07, alt. '04. Hab. Mazatlan : from Spondylus washings ; L'pool Col. Tablet 120 contains all that was found ; viz. 1 perfect valve with a portion of the other. 58. TELLINA LAMELLATA, n. s. T. t. " Tellince lira" simili, sed mag Is aqmlaterali, et carind umbonum carente : lamellis acutissimis, irregulariter distanti- bus ; umbonibus valde pro mine ntibus. A beautiful little shell, very flat, thin, white, transparent ; cardinal and lateral teeth moderately strong ; spaces between the lamellae smooth ; outline oval, very regular except where the umbos project ; flexure wanting. It might have been the young of T. lira, but for the entire absence of the stout umbonal ridge of that species. Long. '1, lat. *13, alt. '03. Hab. Mazatlan ; nestling on back of Chamae and Spondylus Lamarckii, extremely rare ; Lpool Col. Tablet 121 contains 1 pair and 2 opposite valves. 59. TELLINA ??PUELLA, C. B. Ad. C. B. Ad. Pan Shells, p. 283, no. 468. Tablet 122 contains an open pair and a valve which may belong to this species. I think however that the valve is dis- tinct, and displays certain symptoms of Semele, of which I have not seen th.^ very young shell, and am therefore, ignorant of its variation in growth. An unfortunate cough made away with the opposite valve, which however had previously adhered by an external ligament. Whether there be an internal liga- ment as well, repeated microscopic examination has as yet failed to determine. Long. '075, lat. '095, alt. '035. 60. TELLINA ?? DELICATULA, Desk. Proc. Zool. Soc. 1854, p. 363. Tablet 123 contains a fragment which may possibly be the young of this exquisitely beautiful species. Mr. Cuming's unique specimen displays, in addition to the features recorded in Desh.'s description, a pretty general penciling of a dark Sept. 1855. e MAZATLAN BIVALVES colour in irregular radiating lines, crossing the oblique stria?. It measures long. ' 37, lat. ' 64, alt. ' 12. Hob Mazatlan ; Col. Cuming. ?? Mazatlan ; in Spoiidylus washings ; Lpool Col. 61. TELLINA BEEVIEOSTEIS, Desk. Proc. ZooL Soc. 1854, p. 362. This little valve seems to suit the description above quoted : it differs from T. gracillima in being very inequilateral, the lateral and cardinal teeth very strong, and the lamellae very regular, not much raised and rather close. Long. '03, lat. 05, alt. '015. Hab. Central America and California [PGulf], Col. Cum- ing. Mazatlan ; extremely rare, jun ; L'pool Col. Tablet 124 contains 1 valve, and a fragment of a larger specimen. Nothing else was found. 62. TELLTNA ? DENTICULATA, Desk. Proc. ZooL Soc. 1854, p. 365. Shell like a little T. crassa, with exceedingly large and projecting lateral teeth ; muscular impressions strongly mark- ed. Pallial line indistinct. The outside of both valves is worn, and prevents the identification of the species. Long. "065, lat. '07, alt, '02. Hal). Unknown, Col. Cuming. ? Mazatlan ; from Spondylus washings ; L'pool Col, Tablet 125 contains the only specimen. 63. TELLINA , sp. indet. Tablet 126 contains an imperfect valve remarkable for its 3 strong rather divergent cardinal teeth ; the lateral ones are not developed, but there appear spaces for their reception from the opposite valve. Hob. Mazatlan ; off Spondylus ; L'pool Col. 64. TELLINA , sp. indet. Tablet 127 contains a broken valve remarkable for its sub- diaphanous concentric lines on a smooth surface, A fragment MAZATLAN BIVALVES 39 with the surface indented may be an older form of the same species. Shell suborbicular, lateral teeth distinct. Hob. Mazatlan ; from Spondylus washings ; IS pool Col. 05. TELLINA BURNETT, Brod. fy Sow. Zool. Journ. vol. iv, p. 362, t. 9, f. 2. Hani. Descr. Cat. p. 72, t. 13, f. 51. Haul, in Sow. Thes Conch, vol. i. p. 271. = Lucina cristata, Recluz, teste Jay. After examining more than 300 specimens of this most aberrant shell, I cannot quote any noteworthy variations. It seems as though the creature was quite satisfied with its beauty, without endeavouring to improve it. The valves however are occasionally a little more bent, and the striae and knobs a little more or less close. To the shape of a Myadora, it adds the hinge of a Tellina. It has an Atlantic analogue, T. lunulata, found fossil in the Pleistocene beds of S. Carolina. In this however, the left and not the right valve is flat. A species of similar form is found fossil in the palaeozoic rocks, agreeing more with the Atlantic slrell. (Wbodw.J T. Burrieti owes its present wide distribution in collections to this importation from Mazatlan : even this spring a specimen was sold at a London sale for 15s. Long. 1'23, lot. 1'37, alt. '23. Hob. Found in ithe Estuary of Mazatlan, among the shoals of large Pinnse which are left dry at low water, Lieut. Bel- cher. Salango, W.Columbia, Hanley. St. Elena, Cuming. Gulf of California, Mus. Cum. "VY". Columbia, Lieut. Freer in Bristol Museum. Mazatlan ; not uncommon ; Lpool Col. Tablet 128 contains 3 specimens of different ages. GENUS STEIGILLA, Turt. Strigilla Turton, pars, Tellina, auct. A group of Tellinidse conveniently separated for their Lucina-like shape and di- varicated sculpture. - 66. STEIGILLA (Tellina) CAENAKIA, Linn. Tellina carnaria, Linn. Syst. Nat. ed. 12, p. 1119. Donov. Br. Shells, vol. ii. pi. 47. Linn. Trans, vol. viii. p. 57. Dorset Cat. p. 31, pi. 5, f. 6. Turt. Conch. Diet. ^.Vfi.Chemn. Conch. Cab. vol. vi. p. 130, pi, 13, f. 126. Wood Ind. Test. 40 MAZATLAN BIVALVES p. 22, no. n.Dillw. Descr. Cat. vol. i. p. 100. Gmel. p. 3240, no. 70.Sckroet. Einl. t. 2, p. 660. Mont. Test. Br. p. 73. Born. Mus. p. 37, t. 2, f. 14. Desk, in Lam. An. s. Vert. vi. 20d.Hanl. Eec. Sh. vol. i. p. 72, pi. 4, f. 7Hanl. in Soiv. TJies. Conch, vol. i. p. 260, pi. 56, f. 37, 38. Forbes $ Hani. Br. Mol. vol. i. p. SlSMiddendorf Mai. Ross. Abth. iii. p. 60, no. 3 B. M. Cat. D'Orl. Moll. p. 61, no. 536. B. M. Cat. Sagra Moll. p. 36, no. 434. Cardium carneosum, Da Costa, Brit. Condi, p. 181. List. Condi, t. 339, f. 176. Lucina carnaria, Lam. An. s. vert. t. vi. p. 227, no. 8. Flem. Br. An. p. 442. Brit. Mar. Conch, p. 75. Payr. Cat. de la Corse, p. 41, no. 68. Strigilla carnaria, Turt. Dith. Br. p. 118, pi. 7, f. 15. ? = Strigilla miniata, G-ould's plates. I liave not been able to see Gould's description ; but as Mr. Nuttall informs me that this shell is plentiful at Sta. Barbara and as his specimens are even more like the W. Indian ones than the Mazatlan shells are, I presume that the S. mini'ata is a further development of the theory which produced T. simulans, C. B. Ad. It appears to be a very widely diffused species, being one of the very few found JN". and S, of the Gulf of Cali- fornia, and spreading through the Atlantic ocean probably to the Mediterranean and Euxine. Valves have been thrown up on our own shores. The Mazatlan specimens are generally much paler than the W. Indian-, but some have as deep a tinge. The character of the markings is exactly alike, though they vary among themselves in the crowding of the stria?, &c. They are occasionally marked with a yellowish tinge, and are gen- erally more or less stained with black, probably from the mud in which they lived. The shell appears to differ from T. sin- cera, Hani., found by C. B. Ad. at Panama, (rare.) Hani, gives it as from IN". W. Coast of America on the authority of Dr. Sin- clair ; but Nuttall's Californian specimens are undoubtedly T. carnaria. Long. *9, lat. '98, alt. "42. Hob. [Scarborough, Devon and Cornwall, Da Costa, &c.J American Ocean, Wood. Jamaica and Barbadoes, Lister. Curacoa, Gronovius. W. Indies, W. Columbia, Hani. Cuba, Sagra. Brazils, D'Orb. Mediterranean, Lam. E-isso; non Philippi, nee Forbes ; dubitat Middendorf. Corsica, Payrandeau. Naples, P. P. C. Sudate, Black Sea, teste MAZATLAN BIVALVES 41 Ralhke, Siemaschke. Santa Barbara, abundant, NuttalL Mazatlan : not common ; Upool Col. Tablet 129 contains 6 pairs and 2 valves, shewing variations. The smaller valve may be T. cicercula, Phil., in Zeitschr.fur Mai. Feb. 1846, p. 19. I cannot however separate it from S. carnaria, of which it appears the young. The description of T. cicercula exactly applies to this, which is the left valve. Menke in quoting the species among Melchers' Mazatlan Shells, Zeitschr.f. Mai. 1847, p. 188, no. 53, says that it is only the left valve which possesses the sculpture in question : so does the left valve of T. carnaria, and that alone. Menke loc. cit. describes a new species, T. areolata, from the West Indies, intermediate between T. cicercula and T. carnaria, with a similar smooth space on the left valve. Philippi also describes from Mazatlan (loc. cit.) T. lenticula, T. dichotoma, and T. ervilia. In his Abbil. Conch, for Aug. 1846, p. 24, he also gives the ancient T. pisiformis, Linn, (along with Diplodonta semiaspera) as common to Mazatlan and the Caribbean Sea. Mazatlan must be rich in Strigillse, according to Philippi ! 67. PSTRIGILLA LENTICULA, Phil. TeUina lenticula, Phil, in Zeitsch.f. Mai. 1846, p. 19. Tablet 130 contains a broken specimen which probably be- longs to this species, which, says Philippi, while agreeing in form and size with T. pisiformis, has the sculpture of Lucina digitaria. It may however belong to Lucina eburnea, Rve, Conch. Icon. pi. 8, f. 49, found in sandy mud, 11 fm., St. Elena and Panama, Cuming. Hob. Mazatlan, Philippi. ? Do. fragments, off the back of Chama ; L'pool Col. 68. , sp. ind. Tablet 131 contains a fragment of a thin shell of moderate size, perhaps a Psammobia, (possibly an unknown Donax,) strongly angulated, with very fine, slightly rugose stride, coarser on the angular part. It is white, slightly bordered with orange. Hab. Mazatlan ; confined in the mouth of Trivia sanguinea ; L'pool Col. 42 MAZATLAN BIVALVES FAMILY DONACID^E. GENUS IPHIGENIA, Schum. Syn. Capsa, Lam. 1818, (non 1801.) Donacina, Fer. 4 69. IPHIGENIA ALTIOK, Sow. Capsa altior, Proc. Zool. Soc. 1832, p. 196, (teste C. B. Ad.) Mull. Syn. Test. Viv. p. 225. Hani. Descr. Cat. p. 86. Hani, in Suppl. to Wood's Ind. Test. pi. 14, f. 34. C. B. Ad. Pan. Shells., p. 276, no. 453. Shell very variable iu outline, sometimes nearly equilateral, sometimes much produced anteriorly, sometimes incurved at the posterior ventral margin. The outside has the usual olivaceous epidermis. The inside is more or less stained with violet. Bifidity of cardinal teeth more or less developed : lateral teeth almost evanescent in one valve, absent in the other. Smallest specimen measures long. 1', lat. 1*37, alt. '56. Longest 1'88, 2'54, I'll. Aberrant 1'72, 2'12, 1'03. Hob. Gulf of Nicoyia, in coarse gravel, 12 fm. Cuming. Var. Tumbez, thin mud, 5 fm. Cuming. St. Elena, Jay. Panama, extremely rare, C. B. Adams. Mazatlan : very common ; L'pool fy Havre Coll. The Atlantic analogue is I. Brazili- ensis. A closely allied species is from the Gambia ; Chief Justice Ranlcin, Bristol Mus. Tablet 132 contains 5 specimens in the normal state. 133, 5 specimens more transverse. 134, 5 specimens indented. 135, 2 specimens of abnormal growth. 136, 1 specimen with very thin epidermis. 70. IPHIGENIA PLJEVIGATA, ?cujus. This shell is regarded by Dr. Gray as an abnormal variety of I. altior. It has much more the shape of I. Braziliensis. The most deeply indented I. altior is far removed from it. Mr. Cuming has similiar specimens from the same coast, which he regards as an undescribed species. I have seen it with the name Capsa Isevigata, but do not know on what authority. It is characterized by very overlapping umbos ; subcarinated, sub truncated posterior side; deep posterior ventral sinus; MAZATLAN BIVALVES 43 anterior side much elongated. Long. T52, (ad sinum 1*37,) lat. 2 '28, alt. *9, (ad sinum '78.) Hob. Mazatlan ; extremely rare ; L'pool Col. Tablet 137 contains the only specimen I found : Mr. White- head of Liverpool found another. GENUS DONAX, Linn* -p 71. DONAX CARINATUS, Hani. Proc. Zool. Soc. 9 1843, p. 5. Rve. Conch. Icon. pi. 2, sp. 11. Wood's Suppl. pi. 14, f. 28. Shell with a blunt keel, and posterior area covered with slightly expressed striae which are scarcely rugose here and there. Epidermis very thin, deciduous except round the mar- gin. Ventral margin almost always regularly excurved. The purple colour generally predominates in this, as the chesnut in D. culminatus. Form and markings very constant, except, as usual, in the proportion of length and breadth. Long. '93, lat. 1-62, alt. '63. Hob. San Bias, G-ulf of California, Reeve. Tumaco, Hinds, B. M. Mazatlan ; rare ; L'pool Col. Tablet 138 contains 2 specimens in the normal state, and one with two remarkable laminae in the interior of one valve, near the posterior adductor. ^f 72. DONAX CULMINATUS, ? n. s. D. carinatus, var : Hani. ms. teste Cuming. D. t."D. carinato" simili, sed carind multo acutiore, product a, margine ventrali scepe prope carinam paulum incurvato ; niten- tiore ; striis radiantibus obsoletis et crenulatione internd conveni- ente crebrioribus ; area posticd striis radiantibus creberrimis valdeextantibus, granosis, grants versus marginem rngosis ; castaneo-purpureo . I had passed this shell over as the young of D. carinatus, till I obtained a number of large valves with other West Coast shells, which at once displayed the remarkable characters of the posterior area, the sharp ridge, and the very granular crowded striae. Having examined more than 60 specimens of D. carin- * The specific termination being given as feminine in P. Z. S. t B. M. Cat. jy Orb. Moll., Rve. Conch. Icon., Jay's Cat. &c., it is desirable to remember that Donai is masculine both in Latin and Greek : (v. Lex.) In quoting, the termin- ations are altered accordingly. 44 MAZATLAN BIVALVES atus, without seeing the slightest approach to these characters, I am obliged for the present to consider them specific. Size of the Mazatlan specimen ; low. '55, lat.*95, alt. '33. Ordin- ary size, as in D. carinatus. Hob. Mazatlan ; 1 young specimen ; L'pool Col* Tablet 139 contains this specimen, and two valves, probably from the Central American coast. 73. DON AX TE AN S VERSUS, SoiV. Tank. Cat. App. p. 4, no. 226. Rve. Conch. Icon. pi. 6, sp. 36. Known from D. scalpellum, Gray, (Gulf of California) by the peculiar incurving of the anterior dorsal line ; and by the character of the posterior area, which has at the margin one large and two small flexures, while the surface is covered with radiating stria?, very finely and granularly serrated. Long. ' 56, lot. 1*34, alt. '3. Hob. Mazatlan ; extremely rare ; teste R. Tyler, Esq., who found a fresh valve concealed in a Chama from the L'pool Col. The other valve is nowhere to be found. Tablet" 14D contains this valve, most kindly presented by Mr. Tyler. 74. DONAX ASSIMILIS, Hani. Proc. Zool. Soc. 1845, p. 17. C. B. Ad. Pan. Shells, p, 277. no. 454. Rve. Conch. Icon. pi. 2, sp. 10. This species is used for food at Panama, where the natives scoop to its depth, and keeping to the same level find them in great abundance. (C. B. Ad.) Long. '92, lat. 1*36, alt. '51. Hob. Panama, Mus. Cuming. Do. very plentiful, a few inches deep in sand at 3-4ths tide level, C. B. Adams. Mazatlan, Lieut. Green. Mazatlan ; 1 valve only ; L'pool Col. Tablet 141 contains the solitary valve. 75. DONAX PUNCTATO-STEIATUS, Hani. Proc. Zool. Soc., 1843, p. 5. Eve. Conch. Icon. pi. 3, f. 16. Var.=~D. radiatus Vol. in Humb. Rec. vol. ii, 1833. ?=D. flexuosus, Gould's plates. * An extremely similar shell is given in the Bristol Museum as Donax rugosue, Dr. Cutting, W. Indies. MAZATLAN BIVALVES 45 Although there is little doubt that Valenciennes' species is the rayed variety of this shell, and therefore has priority, yet as his description is not accurate enough for certainty, and as it only applies to a very small part of the species, Hanley's expressive name is retained. The punctatostriate character however is by no means peculiar to this shell. Some forms are exceedingly hard to tell from D. Conradi, Desk. ; including D. contusa, jRve. The following are believed to be the main characters of the shell. Surface smooth, shining, with very thin deciduous epidermis, rarely seen. Not grooved, but with rows of extremely fine dots indented as with a bookbinder's tool. Rows often intercalated near the anterior end. Mar- gin with strong squarish crenations inside : the same outside toward the posterior slope ; about the middle, grooves appeal- dividing each, answering to the intercalary rows : at the end a broad surface is channeled off, in which each crenation gives off a fang something like a ( ' ) to join the external rays. This intricate and very characteristic structure will generally tell the species at once from the aberrant forms of D. Conradi. In the posterior 'slope, the punctate rows are very close ; in the lunular portion entirely absent. The ordinary colour is pale yellow or white, sometimes a rich orange yellow ; generally rayed with purple about the lunule with occasional stains elsewhere ; often tinged with green about the posterior slope and umbos, occasionally rayed with brown (=D. radiata, J r ctl.) with the rays often not corresponding on the two valves. Umbos white or pale yellow, sometimes rich transparent orange, sometimes with a penciling of purple, sometimes two purple spots. Shape normally trapezoid, with the umbos sub-central : but often with the posterior part shortened, and the anterior much elongated. The end is then tapering : but often it is short and very gibbous. Ventral margin almost always well developing the angular swelling. Inside generally rich purple. Lateral teeth short but very strong, the anterior truncated : in the opposite valve small. Largest specimen measures long. 1*15, lat. 1*64, alt.'S. Transverse '96, 1'46, '57. Stumpy *79, 1'06, '48. Smallest *18, '26, '11. Hob. South America, Capt. Ld. Byron [?], Mazatlan ; in extreme profusion ; L'pool Col. Tablet 142 contains 15 specimens, normal shape, rich orange yellow. 143, 10 sp. same colour, transverse shape. 144, 9 sp. 46 'MAZATLAN BIVALVES same colour, lunular purple ray on one valve only. 145, 9 ep. same colour, purple rays absent. 146, 10 sp. and 2 valves, pale yellow: this is the most frequent state. 147, 8 sp. white, normal shape. 148, 8 sp. white, transverse. 149, 12 sp. white and pale yellow, with irregular pale violet concen- tric bands. 150, 5 sp. orange yellow, similarly banded. 151, 5 sp. stained with purple and green. 152, 15 sp. yellow, green at umbos and posterior slope. 153, 15 sp. whitish, band- ed with violet, green at posterior slope. 154, 9 sp. plain yellow with greenish slope. 155, 9 sp. white with greenish slope. 156, 7 sp. orange yellow stained with purple. 157, 2 sp. and 1 valve, do, highly coloured, form approaching D. Conradi. 158, 6 sp. with broad brown rays. 159, 6 sp, with very faint rays. 160, 5 sp. shewing distorted growth. Besides these were found a few scores of specimens which, when examining D. punetatostriatus I have generally turned over to D. Conradi ; when examining the latter, have been dis- posed to turn back again. They are here grouped according to the preponderance of characters. Tablet 161 contains D. pune- tatostriatus approaching D. Conradi, 4 sp. whitish. 162, 6 sp. yellow. 163, 3 sp. rayed. 164, 2 sp. yellow, transverse. 165, 3 sp. reddish, transverse. 166, 3 sp. whitish, narrow margin. 167, 3 sp. very gibbous. In all 192 shells, the result of very frequent elimination from an examination of many thousand specimens ; no two probably being exactly alike. 75 (b.) DONAX ? PUNCTATOSTHIATUS, var. CJELATUS. -D. ? punetatostriatus , t. maxime incequilaterali, margine ven- trali mx angulato : superjicie posticd dense liratd, liris ex- pressis radiantibus : interstitiis dense decussatis, lineolis valde impresses : sculpturd partem versus anteriorem, in lineas pwic- tarum mutante, punctis angulatis : margine plerumgue simplici, epidermide densd rugosd tecto. * Nearly 40 specimens have occurred, agreeing in the above characters, while only 2 shewed the least disposition to depart towards the ordinary type. Shape extremely inequilateral, anterior end much prolonged. Sculpture deeply marked on the posterior and posterior ventral part ; with elevated ridges, and the furrows not simple rows of dots as in D- punctato-stria- tus, but with short lines impressed as with a file-cutter's tool. These gradually subside anteriorly into punctate striation, but even then the dots are angulated, not round. There is a large MAZATLAN BIVALVES 47 smooth lunular portion, not specially coloured. The margin is generally simple, nearly as in D. Conradi : and when it has the intercalary grooves proper to D. punctatostriatus, they are rarely carried up into intercalary rows of dots. The epider- mis is remarkably thick round the margin. Colour sometimes white, occasionally yellow, but generally stained with rich reddish purple. Whether it be an aberrant variety of D. punc- tatostriatus, or a distinct species, must be determined when more specimens have been examined, or the animals studied. The largest but not characteristic specimen measured long. '91, lat. 1^37, alt. '57. Hob. Mazatlan ; very rare ; L'pool Col. Tablet 168 contains 3 specimens, white, yellow and purple. -f- 76. DONAX CONKADI, Desk. Proc. Zool. Soc. 1854, p. 351. Rve. Conch. Icon. pi. 5, sp. 29. + D. contusus, Rve. Conch. Icon. pi. 4, sp. 24. + D. Californicus, Conr. teste Desli. m,s. B. M. & Col. Cuming : nequaquam, teste Nuttall. + D. culter, Hani. Proc. Zool. Soc. 1845, p. 14. Eve. Conch. Icon. pi. 4. sp. 21. It is not without the most careful, laborious and often repeated examination of upwards of 1,000 specimens that I have felt compelled to depart from the views of the illustrious Deshayes and the very accurate Hanley, and group together the species above quoted. The D. Californicus, teste Nuttall whose shells were the basis of Conrad's descriptions, is very different from the shells so named by Desh. in the Br. Mus. and Col. Cuming ; the former being a smooth, gibbous, sub- triangular shell, more like a young D. punctatostriatus, though quite distinct. The name Conradi is preferred to culter which has priority, as expressing the adult form, and as leaving contusus and culter for the use of those who believe in the species, without introducing confusion. The shells wrongly called D. Californicus are simply the white variety of the forms contusus and culter. This creature loves liberty both in form and colour. The shape is generally transverse, not unlike the large variety of D. anatinus, slightly swollen ventrally, with a flattening towards the posterior end. Sometimes it tapers off at the anterior part, which is then somewhat flattened : sometimes the whole shell 48 MAZATLAN BIVALVES is very gibbous : sometimes subtriangular, and even taking the form of D. punctatostriatus. Th ? lines of growth shew that the adult by no means thinks it necessary to preserve the form of early life : it being very common to observe the posterior part much developed in the young, while it is narrowed off in matu- rity ; or the shell is sometimes sub-oval when young, and very transverse afterwards. In colour there are similiar variations j the young shell abounding more in purple, while the adults reserve that colour for the inside, and content themselves with a greenish gray. Or a shell of an ochre yellow when young will change afterwards to a purplish tinge. The prevailing colour is a greenish gray, tinged with purple. This is very bright in the young, very dull in the adult. The purple is often absent in the adult, sometimes in the young ; rarely predominant. Ochre yellow sometimes prevails, in the young beautifully shaded into purple or white. The white variety is tolerably common, with gradations into the other colours ; and often with irregular rays from the umbo to the anterior margin, which is but rarely seen in D. punctatostriatus. The same colours intensified are seen in the young shells, and noted by Hani, in his description of D. culter. In these the changes in form are extraordinary ; some being nearly triangular, while others take an extremely elongated form, with a posterior ventral sinua- tion (D. culter, var. a, Hani.) ; but the intermediate forms are so various that I have not been able to separate them. The middle stage of growth of the gibbous form is D. contusus, Rve., a species described from a single specimen in the Cumingian Collection. The surface of the shell is punctatostriate ; with the dots finer and the rows further apart than in the last species. Towards the ventral part they generally subside into plain striae. On the anterior part, they are often crowded and irregular, having jagged edges or running into little lines which are sometimes confluent. A large lunular portion is smooth. The general aspect of the shell is rather glossy^, especially in the young shells. The form contusus often retains the margin marks one after another, giving the shell a tiled appearance. Having examined every specimen under the glass, I am unable to note any constant characters in the markings co-ordinate with the changes of form and colour. The crenations are gene- rally simple, without the broad marginal band conspicuous in D. punctatostriatus, and not shewing the intricate markings at the anterior end. I have observed no specific differences in the interior : the teeth and impressions are as in D. punctato- striatus, making allowance for the greater or less elongation of MAZATLAN BIVALVES 49 the shell : colour generally deep purple, with more or less of white. Epidermis very thin, deciduous. Umbos purple with white spot, occasionally 'rich orange. A transverse specimen measures long. '83, lat. 1*52, alt. '5. A subtrigonal one '92, 1'5^ ,, '52. The smallest '06, '0$ '02. 2Iab.(D. culter) Mazatlan and Acapulco, Col. Chiming. Maz- atlan ; common (the adult state rare, perhaps from burrowing deeper in the sand) ; L'pool CoL Tablets 169 173 contain forms intermediate between this species and D. punctatostriatus. 169, 4sp, rayed. 170, 4 sp. purplish yellow. 171, 5 sp. purplish white. 172, 7 sp. yellow- ish.? 173, 10 sp. more transverse. In the following series (except in the subtrigonal forms) the very young are D. culter, Hani., and the intermediate ones are generally D. contusus, Rve. : the white ones of both forms are D. Californicus, Desk, not Conr. Tablet 174 contains 10 sp. with purple tinge predominant. 175, 9 jun. and 2 adult, very transverse, margin sinuous, purplish gray. 176, 9 sp. less transverse. 177, regular form, 1 pair, 2 valves very young. 178, 11 sp. very oval and regular. 179, 12 sp. less transverse, more gibbous. 180, 12 sp. very gibbous. 181, 9 sp. subtrigonal. Yellowish var : 182, 9 sp. transverse. 183, 7 sp. oval, gib- bous. 184, 6 sp. subtrigonal. Greenish var : 185, 11 sp. transverse. 186, 10 sp gibbous. 187, 10 sp. subtrigonal. Greenish white : 188, 12 sp. very transverse. 189, 6 sp. sub- oval. 190, 7 sp. subtrigonal. Purplish white : 191, 12 sp. transverse. 192, 7 sp. subtri- gonal. White var : 193, 12 sp. very tranverse, 194, 12 sp. suboval ,(that marked* is curiously insequivalve with sinuous margin.) 195, 12 sp. subtrigonal. Bayed var : 196, 12 sp. very transverse, 197, 18 sp, oval. 198, 12 sp. subtrigonal. Tablet 199 contains 5 young shells (culter,) with the umbonal spot much developed. 200, 3 sp. (form contusus) yellowish white. 201, 3 sp. yellowish purple white* In all 292 specimens, no two being exactly alike. Sept. 1855. / 50 MAZATLAN BIVALVES 'f- 77. DONAX NAVICULA, Hani. Proc. Zool. Soc. 1845, p. 15. -C. B. Ad. Pan. Shells, p. 278. no. 456. Eve. Conch. Icon. pi. 4, sp. 18. A charming little species, both for its extreme beauty, and the distinctness of its characters. Shell singularly swollen, margin gibbous, scarcely shewing crenations beyond the edge at the anterior end : clothed with very glossy epidermis, be- neath which are obsolete striae. Ordinary colour greenish white, gradually assuming darker shades, often beaked with orange, generally more or less rayed, and ending in dark orange chesnut. Inside from white to fawn, ending in deep purple. Often (not always) with two streaks of purple within and without, bounding the lunular and posterior areas. It varies in the greater or less elongation, and in the ventral mar- gin which is sometimes incurved. One monster was found, shewing more prominent striae, long '44, lat. '9, alt. '29. Ordinary size "3, '66. .23. SmaUest '2, '43, '14. Hob. Gulf of Kicoyia, Cuming. Panama, E. Jewitt, C. B. Adams. Mazatlan ; not uncommon ; L'pool Col. Tablet 202 contains 5 specimens, most common variety, very pale. 203, 3 darker, tipped with orange. 204, 3 darker, slightly rayed. 205, 4 normal state, rather dark, indistinctly rayed. 206, 3 sp. rays more evident, tipped with orange. 207, 3 sp. brownish orange. 208, 3 the same deeper. 209, 3 rich dark brown. 210, the monster. In all, 28 specimens. FAMILY GENUS MACTEA, Lin. 78. MACTRA EXOLETA, Gray. r- Mag. Nat. Hist. 1837, p. 372. Eve. Conch. Icon. pi. 4, sp. 16. This exquisitely beautiful species is recognized easily by the angle at the posterior side, and by the great prolongation of the flattened anterior margin, which rises into a sharp keel dividing the lunular portion. It diifers from M. alata, Speng. ( = M. carinata, Lam. teste Eve. ?) in having no laminar keel on the posterior angle. The epidermis which is deciduous, but closely adherent when fresh, only shews striae of growth, and gradually fades away towards the umbos which are always MAZATLAN BIVALVES 51 white. The shape is very constant, only occasionally varying in the shortening of the anterior portion. The posterior lateral teeth are extremely small, the anterior of moderate size. Pal- lial sinus rather small and narrow. I have seen this shell labeled as from the W. Indies, but without authority. It has probably been mistaken for Lutraria carinata, teste Gould, which he gives as the Caribbsean analogue of Lutraria ventri- cosa, ( = Mulinia ventricosa, C. B. Ad. Pan SJiells, p. 293,) which is given from Panama and Mazatlan. ? Can this be the M. exoleta of Gray. Y. Proc. Bost. Soc. N. H. iv. 89 ; a work which, alas ! I have not been able to see. In the very young shell, the anterior margin is but little produced, and the pos- terior tooth is moderately large. Youngest specimen measures long. *16, lat. '21, alt. *1. The most ventricose 2'8, 3'73, 1'86. The largest 3'84, 5*33, 2*5. Hob. Cape Horn [?] and West Columbia, Reeve. Guayaquil, Hinds. Mazatlan ; not uncommon, L'pool Col. Tablet 211 contains 1 very young valve. 212, 3 specimens ; one young, of exquisite beauty ; one with the epidermis re- moved, shewing the interior (presented by J. Hibbert, Esq.) ; the other very large. 79. MACTEA (SPISULA) FBAGILIS, Ckemn. Conch Cab. vol. vi. p. 236, pi. 24, f. 235. .#. M. Cat. D'Orb. Moll. p. 56, no. 489. #. M. Cat. Sagra Moll. p. 35, no. 418. = Mactra ovalina, Lam. An. s. Vert. ed. Desk. vi. 104, no. 21, (teste Gray.) =Mactra Braziliana, Lam. An. s. Vert. ed. Desk. vi. 106, no. 27, (teste DesJi.) =Mactra oblonga, Say, (teste live.) Mr. Cuming having compared this shell critically with both larger and smaller specimens in his collection, writes that it certainly belongs to M. fragilis, Ckemn. (according to Desk.) The texture and epidermis are very different from M. velata, Phil, of which, for geographical reasons, I had thought it might be the young. It is remarkable for its double posterior ridge, great flatness, and large gape on each side. Long. 1*36, lat. 1-93, alt. '64. Hob. W. Indies, Honduras and St. John's, Mus. Cuming. Cuba, Sagra. Rio Janeiro, Lalande, jun. (teste Lam.) 52 MAZATLAN BIVALVES Brazils, Bio de Janeiro, Patagonia ; "Baie Blanche, Voy. no. 130," jyOrbigny. Mazatlan; one specimen was sent, quite fresh, papered up along with the Semeles ; L'pool Col. Tablet 213 contains the specimen. 80. MACTEA (MULINIA) ANGULATA, Gray, ms. Rve. Conch. Icon. pi. ix. sp. 34. This species is known at once from the young of M. exoleta by its stout, subtrigonal growth, the shortness of the anterior portion and the rather distant umbos. The epidermis is extreme- ly thin, gradually passing off towards the anterior portion, as in M. exoleta; but differs in being loose, lying in irregular concen- tric folds, fringed at the posterior angle. The hinge teeth are large and prominent ; lateral ones very finely shagreened. The muscular impressions are singularly close to the margin of the shell ; pallial sinus small, oval. ? Can this be the M. donaciformis of C. B. Ad. (Pan. Shells p. 293,) as the true M. donaciformis is given by Rve. as from JS". Zealand.* This shell seems also to have relations with M. goniata, Gray, ms. (Proc. Zool. Soc. 1854, p. 70,) and with M. carinulata, Desk. (Proc. Zool. Soc. 1854, p. 67 : Eve. Conch. Icon. pi. 10, sp. 38), both from the gulf of California. Long. 2'25. lat. 3'05, alt. 178. Hob Gulf of California, Beeve. S. W. Mexico, P. P. C.-~ Mazatlan ; a very few specimens were found with M. exoleta : L'pool Col. Tablet 214 contains two specimens ; one young with the epidermis perfect ; the other adult. GENUS GNATHODOST, Gray. Gnathodon, Gray, Am. Journ. of Science ? 1830. Bangia, Desmoul. Ac. Soc. Lin. de Bord. 1831. Clathrodon, Conr. Sillim. Amer. Journ. 1833. , JL 81. GNATHODON (Bangia) TEIGONA, Petit. G. t. solidd, subtrigonali, alba, epidermide flavescente, pos- terius rugosa, induta ; plus minusve incequilaterali, parte pos- teriori angulo db umbonibus decurrente indistincte separata; imbonibus subcentralibus, distantibus, non spiraliter recurvis ; * Reeve however, under M. carinulata, sp. 38, speaks of M. donacifcfrmis as from the Gulf of California. ? Is it authenticated from both localities. MAZATLAX BIVALVES lineis subobsoletis utrinque ad marginem dorsalem decurrentibus, aream rkomboideam ut in Area describentibus ; anterius lineis lunulam magnam demonstrantibus : intus dentibus later - a lib us sub & qua lib its , tenuissime rugosis, non striatis ; nnu pallii minimo. The shell differs from the typical species in its regular form, and consequent size of the anterior tooth, which in G. cuneatus is very short and bent up. If this be regarded as of generic importance, the name Hangia may be retained for this species. It has somewhat the external aspect of Mactra subtruncata, but the rounded character of the hinge teeth shews its affinities to be with Gnathodon. It has the aspect of a brackish water shell, and the pallial sinus is extremely small. The lines of growth outside are often beaded, which is the more remarkable as the margin is sharp, not crenulated. It varies, like other bivalves, in being more or less swollen ventrally, and less or more produced posteriorly. This constantly variable character among bivalves can hardly be the result of sex, as in the myriads of shells of Veneridse &c. which I have examined, instead of ranging under two heads, there is every conceivable gradation of form. Indeed one of our most accurate British malacologists denies the separation of sex in the Lamellibran- chiata altogether: v. Clark, Moll. Test. Mar. Brit. p. 191. Long. '82, lat. 1*08, alt. *55. Hob. Mazatlan ; rare ; L'pool Col. Tablet 215 contains 4 specimens, the largest and the smallest, and two intermediate ones shewing opposite forms of growth. FAMILY VENERID^E. The genera in this family are so slightly denned that shells classed in different sub-families by one naturalist will belong to the same genus of another. The most accurate divisions are those proposed by Dr. Gray, which will be found in Desk. J5. M. Cat. Venerida, 1853. Many tiny shells were found among the shell washings, which there has been great difficulty in affiliating, from not having intermediate specimens, and from the change of form and hinge characters between the fry and the adult. It is probable therefore that there are many errors in the young of the following species. 54T HAZATLAN BIVALVES GENUS ?CLEMENTIA, Gray. B. M. Cat. Yen. p. 197. 82. ? CLEMENTIA GEACILLIMA, n. s. ?C. t. subtrigojid, tenuissimd, alba, diaphand, concentrice liratd, liris rotnndis, approximatis ; postice prolongatd. Intus dent. 3-4 diver gentibus, minutis : ligamento vix monstrante. This shell comes nearer to dementia than to any other genus I know ; nor is there any reason why it should not be found on the American shores of the Pacific. Some may rank it with Tellina. The teeth are more equally divergent than in the typical species. Long. *09, lat. '13, alt. *5. Hob. Mazatlan ; from backs of Chamse and Spondylus La- marckii ; extremely rare ; L'pool Col. Tablet 216 contains 1 perfect and 2 broken valves. GENUS TKIGONA, Megerle. Trigona, Megerle. teste Desk. S. M. Cat. Ven. p. 4&Muhl- feldt, teste Wbodw. Man. Moll. pt. 2, p. 305. =Trigonella, Conr. Hinds. = Cytherea (pars) Lam. Known from Cytherea and Dione by the trigonal shape ; numerous irregular cardinal and long lateral teeth ; and by the velvety periostraca outside the epidermis, of a dull white colour, which, being mistaken for dirt, is generally very care- fully cleaned off by collectors. Under the microscope, this appears like an irregular mass of needle-like crystals. JL 83. TEIGONA RADIATA, Sow. Cytherea radiata, Proc. Zool. Soc. 1835, p. V&.Hanl. Descr. Cat. p. 106. Sow. Thes. Conch, p. 619, pi. 128, f. 2831. C. B. Ad. Pan. Shells, p. 273, no. 446. Trigona radiata, Desh.-S. M. Cat. Ven. p. 51, no. 19. Yenus Solangensis, B. M. Cat D'Orb. Moll. p. 68, no. 607. Trigona Byronensis, Gray, Anal. t. 8. p. 304, 1838. = Cytherea corbicula, MenJce (non. Lam.) in Zeit.f. Mai. 1847, p. 189, p. 54 : also Sow. Thes. Conch, p. 614, no. 7 (pars), pi. 128, f. 39 (f. 37, 38 excl.) MAZATLAN BIVALVES 55 ? + (var.) Cytherea semifulva, Menke in Zeit. f. Mai. 1847, p. 190, no. 56. ? = (var.) Cytherea gracilior, Sow. Thes. Conch, p. 615, pi. 128, f. 32. (Trigona g.) Desk. B. M. Cat. Yen. p. 53, no. 26. ? + (var.) Cytherea Hindsii, Hani, in Wood Suppl. pi. 15, f. 39 : Proc. Zool. Soc. 1844, p. 110. Sow. Thes. Conch, p. 614, pi. 128, f. 27. (Trigona H.) Desk. B. M. Cat. Yen. p. 53, no. 25. ?? + (var.) Cytherea intermedia, Sow. TJies. Conch, p. 615, no. 12, pi. 128. f. 35. (Trigona i.) Desk. B. M. Cat. Ven. p. 49, no. 13. ( Compare the Atlantic species T. mactroides, Born, Chemn. Dillw. [non Lam. nee Sow.] Desh. B. M. Cat. Ven. p. 51, no. 20 : B. M. Cat. Sagra Cub. p. 40, no. 476 : = C. corbicula, Lam. Hani. Phil. Sow. [pars,] Grray, Menlce \_Zeit.f. M. 1849, p. 40, non supra loc. cit.] Also T. Dillwyni, Desh. B. M. Cat. Ven. p. 49, no. 14 : = C. mactroides, Sow. Thes. Conch, p. 615, pi. 128, f. 36 [non Lam.'] The W. African analogue is T. tripla Lin. : Desh. B. M. Cat. Ven. p. 52, no. 23 : Menlce in Z.f. 7^1849, p. 40. The Chinese ana- logue is T. ventricosa, Gray, B. M. Cat. Ven. p. 53, no. 24.) This shell is never so tumid at the umbos [straight] as in the African or [twisted] in the East Indian species : to the West Indian T. mactroides however some forms bear so close an analogy that Menke (and in part Sow.) may well be pardoned for not discriminating them. Menke remarks that "its forms are as various as its fatherland one should rather say mother- sea." At Mazatlan however its forms and colours vary ex- tremely in the very same mother-sea. It is generally pretty equally swollen, but sometimes much flattened towards the ventral part. Occasionally the whole shell is much compressed, in which state it may possibly be T. intermedia, Sow. The ventral line is sometimes well rounded, sometimes nearly straight. Sometimes the posterior part is much produced, occasionally however the anterior. It would be hard to give a specific description that would include all the varieties and yet exclude the W. Indian specimens : the general habit however is so far distinct that I have not felt at liberty to follow Menke in uniting them.* There is often, not always, an anterior gape, * I have unfortunately distributed several specimens of the white var. of the form T. Hindsii, as another species j but having then examined only about 100 specimens, I thought the velvety epidermis was peculiar to that form and colour. I have since founfit however (though it is generally cleaned off) on the typical T. radiata ; and after often repeated examinations of some 600 specimens, I am compelled to unite them. 56 MAZATLAN BIVALVES occasionally rather large : the margin is generally thickened in that part, as in Donax. The growth of the teeth is very irregular. The posterior tooth is rugosely crenated in adoles- cent shells, but in very young ones this is not the case, and in old specimens it is frequently obsolete : in this state it becomes the T. semifulva of Menke. If I have rightly affiliated the young specimens, ('03 across) the creature begins as a sub- orbicular body, with very swollen and pointed umbos, white with a purplish tinge, the anterior part swollen. There are then only 2 teeth ; an enormous anterior lateral, and a small posterior, nearly at right angles. Gradually these lessen in comparative size, while the cardinal teeth are formed one by one, and the creature assumes a trigonal and afterwards a transverse form. The youngest which is undoubtedly T. radi- ata, (about '22 across,) has not yet attained its full compliment of teeth, and does not display crenations. In colour, the shell is generally more or less brown ; either in a diffused hue, or in in rays of endless variety, sharp or mottled ; straight or zigzag ; with the umbos almost always tinged with purple at the tip, with or without a white patch, bifurcate or irregular. Harely however most of the forms take a uniform dull white, without purple tips. The shell generally forms irregular ridges of growth, as in Dione aurantia. A transverse specimen measures long. 1 '72, lat. 2 ' 23, alt. 1 ' 14. A thick 1*88, 2*3, 1'34. A rounded 1*57, 1*82, 1. A produced 171, 1*97, 1*11. Sal). Salango and Xipixapi ; in sandy mud, 9 fm ; Cuming. Ecuador; Xipixapi, D'Orbigny. Panama, extremely rare ; C. S. Adams. Mazatlan ; very common ; L'pool fy Havre Coll.(T. Hindsii) Guayaquil Bay, Mus, Cuming. (T. gra- cilior) loc. incog. (T. semifusca) Mazatlan, MelcJiers. (T. intermedia) California, Mus. Cuming. Tablets 217 235 contain specimens arranged to. shew varia- tions in form. 217, 3 sp. very transverse. 218, 3 sp. rather less. 219, 3 sp. somewhat rounded, tumid. 220, 4 sp. very regularly rounded. 221, 1 sp. ventral line flattened. 222, 1 sp. posterior part produced. 223, 1 sp. anterior part pro- duced. 224, 3 sp. gibbous. 225, 3 sp. subtriangular. 226, 4 sp. and a valve, subtriangular, produced anteriorly. 227, 1 sp. extreme form, flat, gaping, 228, 1 sp. with crenations outside, as sometimes in Grnathodon trigona. 229, 1 sp /dis- torted growth, gaping extremely. 230, 1 sp. mantle cut. MAZATTAN BIVALVES 57 White or very faintly streaked variety. Tablet 231 contains 4 sp., regular form, various ages. 232, 1 sp. flattened, round- ed. 233, 1 sp. produced ventrally. 234, 1 sp. transverse, gaping posteriorly. 235, 1 sp . very transverse. Tablets 236 241 are arranged to shew transitions of colour ; but many of the specimens are also remarkable for form. 236, 3 sp. white, with very faint brown markings. 237, 3 sp. brown rays narrow, interrupted. 238, 2 sp. very narrow and numerous rays. 239, 3 sp. with broad, sharp rays. 240, 3 sp. brown predominant. 241, 3 sp. diffused brown. Tablet 242 contains 6 pairs, extremely young, which pro- bably belong to this species. Tablet 243 contains 2 young valves, which may belong to the transverse white variety. f 84. TRIGONA HUMILIS, n. s. T. t. juniore ovali, wmbonibus appressis ; ? adultd parvd, subtrigond, margine ventrali excurvd, latd; umbonibus non incurvis, parum prominentibus ; Icevi, vel striis incrementi exili- bus : fused, intws mdculo pu rp ur eo dente postico ; dent, lat., antico brevi, solido, postico longo, exili ; card. 2-3 parvis ; lined pallii a margine remotd, sinu parvd, subascen- dente ; ligamento celato, brevi ; epidermide tenui. This shell might be taken for the young of Dione chionsea, but for the entire absence of spirally recurved umbos ; it differs also from the shells supposed to be the young of T. radiata in the flatness of the umbos and the comparatively small size of the teeth. Not being able to affiliate it with any satisfaction, I have been compelled to describe it provisionally. In the youngest stage only the lateral teeth are prominent, and the shape is almost oval ; then the anterior tooth turns round and makes a cardinal, and afterwards the other cardinal teeth ap- pear. There seems always a stain of purple inside the ligament. When adult, it becomes subtrigonal, with the dorsal margins rather straight. Neither lunule nor area are defined. The youngest specimen measures long. '02, lat. '035, alt. '015. The largest *11, '16, '07. H$b Mazatlan ; rather uncommon, in Spondylus and Chama washings ; L'pool Col. Tablet 244 contains 2 pairs united, and 4 pairs of valves of different ages. 58 MAZATLAN BIVALVES 85. TKIGONA ARGENTINA, Sow. Cytherea argentina, Proc. Zool. Sac. 1835, p. 46. Hani. Descr. Cat. p. 105: Wood's Suppl. pi. 15, f. 15. Phil. AbUld. Condi. Cyth. pi. 3, f. 5. Sow. TJies. Conch, p. 622, pi 129, f. 62. ?Menke Zeitsch.f. Mai. 1847, p. 189, no. 55. Trigona argentina, Desh. B. M. Cat. Ven. p. 50. no. 16. This shell may be known at once from those varieties of T. radiata which most approach it by the very remarkable and constant shape ; being most regularly excurved along the ven- tral margin, incurved on the anterior and straight on the pos- . terior dorsal lines. Colour dull white,itvith light. olive green epidermis ; often with two rays of violet within. The anterior cardinal tooth is much larger than in T. radiata, and the pos- terior tooth does not display rugose sulcations. The anterior adductor scar is less deeply impressed and more evenly bounded. Long. 2-12, led. 2'6, alt. T52. Hal). Grulf of Nicoyia, in sand banks at low water, Cuming. PGuaymas, Lieut. G-reen, (Gould ms.*). Mazatlan ; Mel- chers. Do. very rare ; L'pool fy Havre Coll. Tablet 245 contains 3 minute valves, the smallest '04 across, which may belong to this species. Tablet 246 contains 2 specimens. The smallest displays the violet rays, and an abnormal lamina within. 86. TKIGONA ?? CEASSATELLOIDES, Conr. Ann. Nat. Hist. Soc. Philad. t. 7, p. 253, pi. 19, f. 17. Hinds, Voy. Sulph. Moll. p. 65, pi. 21, f. I Desh. B. M: Cat. Ven. p. 46, no. 1. Cytherea crassatelloides, Hani. Descr. Cat. p. 106: Wood Suppl. pi. 15, f. 32. Sow. Thes. Conch, p. 612, pi. 127, f. 13. Tablet 247 contains 2 small valves, (the smallest '04 across) which have the shape aud thickness of this species. Their identity however is doubtful, T. crassatelloides belonging strictly to the Californian fauna, where it attains a diameter of 5 inches. (Woodw. Nutt.) * Dr. Gould writes "Venus straminea, Conr. = argentina ?" Tapes straminea, Conr. is the Californian representative of T. histrionica or T. grata. It is pJO- bable therefore that our shell is meant, as Tr. argentina is a well known and constant form. It is possible however that it may not be known to Gould, and that the first shell is meant : also that Menke's Cytherea argentiua is one form of T. radiata. MAZATLAN BIVALVES 59 ffab. Sta. Barbara ; Nuttall, Col. Jewett&&n Diego ; Lieut. Green. Mazatlan ; Lieut. Green. (Grould ms.) ?? do ; from shell washings ; Lpool Col. _(- 87. TEIGONA PLANULATA, Brod. fy Soiv. Cytherea planulata, Zool. Journ. vol. v. p. 48. Sow. Gen. f. 2. Rve. Conch. Syst. vol. i. p. 94, pi. 69, f. 2. Hani. Descr. Cat. p. 105. Zool. Beech. Voy. p. 151, pi. 43, f. 6. Sow. I7ies. Conch, p. 618, no. 20, pi. 127, f. 13. Venus planulata, B. M. Cat. DOrb. Moll. p. 66, no, 587. Trigona planulata, Gray Cat. Cytli. Anal. vol. viii. p. 304. Desk. B. M. Cat. Ven. p. 48, no. 8. + Var. suffusa, Sow. Proc. Zool. Soc. 1.835, p. 46. + Cytherea undulata, Sow. Thes. Conch, p. 618, no. 21, pi. 127, f. 12. (Trigona u.) Desk. B. M. Cat. Ven. p. 48. no. 9. = Donax Lessoni, Desk. JEnc. Meth< vers. t. 2. p. 99. (teste Desk.) Cytherea mactroides, Lam. (non Born nee Sow.) An. s. Vert. vol. vi. p. 307, no. 27.Deless. Rec. de Coq. pi. 8, f. Z.^Hanl. Descr. Cat. p. 99 : Wood Suppl. pi. 13, f. 17. The very illustrioiis Deshayes in his later works seems much more disposed to the multiplication of species than he was in his earlier edition of Lamarck. He follows Sow.jun. in divid- ing the C. planulata of Brod. fy Sow. The C. undulata is discriminated by its more equal form, greater solidity, absence of posterior gape, distinctness of lunule and style of painting. I have not found any one of these characters constant. The species varies almost as much as its more swollen congener, T. radiata. In form there is a gradual passage between the two. The undulatse are if anything thinner than the planulatse. The breaking up of the coloured rays proceeds by insensible gradations, and the colouring of the interior varies greatly. The gaping is either posterior, or anterior, or both, or some- what ventral, or none, just as it happens. The beaks are scarcely ever tipped with purple. The painting of the two valves does not always correspond. The teeth are very small and angular j anterior lateral much prolonged. The W. African analogue is T. bicolor, Hani. Typical form measures long. 2', lot. 2*3, alt. 1*. Var. undulata 1'78, 2'2, '88. Hob. Panama, Cuming. Chili ; Coquimbo ; TfOMgny. Found abundantly near Mazatlan ; Lieut. Belcher. Maz- atlan ; not common ; Lpool Col. Var. suffusa ; Salango, sandy mud, 9 fm. Cuming. Var. undulata, do. Cuming. 60 MA2ATLAN BIVALVES Tablet 248 contains 3 young specimens, dull ash colony slightly rayed, one with slight gape. 249, 1 sp. adolescent, closed, slightly rayed on one val^e, the other mostly dull brown. 250, 1 sp. larger, closed, margin waved. 251, 1 fine adult sp. gaping posteriorly and ventrally. 252, 2 sp. very slightly gaping, rays clouded. 253, 1 do., form undulata, gap- ing nearly all round. 254, 2 do. form and colouring intermedi- ate ; one gapes posteriorly, the other ventrally. 255, 2 pairs and 2 valves, form undulata, large posterior gape. 256, 3 do. valves closed ; of which one is nearly white inside, another of a rich diffused violet. Similar differences of colour may be observed in the other specimens, GENUS DOSINIA, Scopoli. Dosinia, Scop. Intr. ad Hist. Nat. p. 399, (1777). Desk. B. M. Cat. Ven. p. 5. Artemis, Poli, Test. utr. Sic. p. 98, 1. 1. (1791). 88. DOSINIA ? PONDEROSA, Gray. Artemis ponderosa, Gray Anal. (1838), vol. viii. p. 309. Rve. Conck. Icon. pi. 1. f. k.Hanl. Descr. Cat. p. 109, pi. 19, f. 38.&M0. Thes. Conch, p. 656, no. 3, pi. 140, f. 2. Dosinia ponderosa, Desk. B. M. Cat. Ven. p. 7, no. 5. Cytherea gigantea, Phil. Abbild. Conch. Cyth. p. 33, pi. 7, f. 1. p. 9, no. 7. Venus cycloides, B. M. Cat. D'Orb. Moll. p. 67, no. 596. A single specimen in beautiful condition, after being referred to D. concentrica (Grulf of Mexico), and D, distans (unknown ; probably Puerto Portrero), was at last doubtfully affiliated to this species by Mr. Cuming. A larger specimen procured since from another dealer, and probably from the same collec- tion, confirms the judgment. It is remarkable for the very orbicular form, slightly angulated beyond the ligament ; deeply cut lunule ; and very regular and distant sulci, not obsolete in the middle, of which, measuring from 1 to 1*5 in. from the umbo, there are only 8. The epidermis is extremely glossy, of a very light straw colour. Long. 1*64, lat. 1*74, alt. '73. Hob. Grulf of California, in sandy mud at low water, Sowerby. Peru; Payta, D'Orligny. Mazatlan ; extremely rare; L'pool Col. Tablet 257 contains the specimen. MAZATLAN BIVALVES 61 89. DOSINIA ANNJE, n. s. D.t. co mp ressd, elongatiore, marginibus aqualiter arcuatis : sulcis concentricis subdistantibus, haud i mp res- sis, medio subobsoletis ; lunuld oblongd, subimpressd; lacted, epidermide flavescente, medio tenuissimd ; dentibus hand valde diver gentibus : sinu pallii haud magno, angulato, apice ad m arginem ventralem muse, adduct. ascendente . This fine , and (for a Dosinia) well marked species is known from D. ponderosa by its greatly elongated form ; from D. Dunkeri by its larger size, flatter growth, smoother ribs (the difference being at once perceived by drawing the nail along the two shells) which are obsolete in the middle ; and especially by the shape of the pallial sinus, which in D. Dunkeri almost always points to the middle, in this towards the ventral edge of the anterior adductor. Long. 2*44, lat. 2*35, alt. 1*12. Hob. Mazatlan ; very rare ; L'pool Col. Tablet 258 contains a young and a full grown specimen. A- 90. DOSINIA DUNKERI, Phil. Cytherea Dunkeri, Phil. Abbild. Conch. Cyth. p. 4. no. 5, pi. 2, f. 9. (Oct. 1844.) Artemis Dunkeri, Rve. Conch. Ic. pi. 6, f. 34. Ad. fy Rve. Voy. Samarang, p. 78, pi. 21, f. 17. Soiv. Thes. Conch, p. 657, no. 7, pi. 140, f. 5. C. J9. Ad. Pan. Shells, p. 274, no. 448. Dosinia Dunkeri, Desk. JB. M. Cat. Ven. p. 8, no. 9. = Artemis simplex, Hani. Proc. Zool. Soc. Jan. 1845, p. 11 : Descr. Cat. Ap. pi. 19, f. 41. Eve. Conch. Ic. pi. 10, f. 9. Sow. Thes. Conch, p. 657, no. 8, pi. 140, f. 6. (Dosinia s.) Desk. B. M. Cat. Ven. p. 9, no. 11. Cytherea Pacifica, (Mus. Berol.) Trosch. in Wiegm. Archiv. p. 324, (non Dillw.) After very patient but altogether ineffectual attempts to separate D. simplex of the monographs from D. Dunkeri, in the many hundred specimens which have passed under review, I am imformed by Mr. Hanley himself that his species is the same as Philippi's ; and as the name of the latter bears date a few months earlier, it is necessary to preserve it. The shell is known by its very rounded, inflated form, more or less produced ventrally ; the more produced form is the D. simplex of the monographs. It varies somewhat in the closeness of the striae, Sept. 1855. g 62 MAZATLAN BIVALVES but with these exceptions is tolerably constant in character. Colour white, with thin light straw-coloured or yellowish epi- dermis. A typical specimen measures long. 1*73, lot. 1*76, alt. 1'04. A produced 1*7, 1'68, '92. Hob. Pacific shores of Mexico, Philippi. Panama, St. Elena, Mus. Cuming, (Hani.) Panama, not common, C. B. Ad- orns. Eastern Seas, A. Adams. Mazatlan ; very common ; L'pool fy Havre Coll. Tablet 259 contains 5 young specimens, the smallest *81 across. 260, 5 do. adult. 261, 5 do. jun. closer strise. 262, 5 do. adult. 263, 6 sp. distant striae. 264, 5 sp. adolescent, produced form. 265, 4 do. adult. GENUS CYCLIC A, Desk. Cyclina, Desk. Traite Elein. (1849) i.^ pi. 14 bis, f. 2022. B. M. Cat. Yen. p. 29. As the animal of this genus is said by Gray to be like Dosinia r while that of Lucinopsis (Forbes fy Hani. Br. Moll. 1848, vol. L p. 433) is very different, being closely allied to the Telliiiidse, (ClarJc, Moll. Test. Mar. Brit. pp. 132 et seq.) both genera will have to be preserved ; and the location of different species must await our knowledge of their animals. 91. CYCLINA SUBQUADBATA, Hani. Artemis subquadrata, Proc. Zool. Soc. 1845, p. 11 : Descr. Cat. App. pi. 15, f. 39 Rve. Conch. Icon. pi. 3, f. 15. Sow. Thes. Conch, p. 661, pi. 141, f. 27. Lucinopis subquadrata, P. P. C. Cat. Prov. Cyclina subquadrata, Desk. B. M. Cat. Ven. p. 31, no. 4. = Arthemis saccata, Gould, Proc. Bost. Soc. Nat. Hist. 1851, p. 91 : Mex. $ Cal. Shells, p. 23, pi. 15, f. 2. (Artemis s.) C. B. Ad. Pan. Shells, p. 275, no. 449. Cyclina s.) Desk. B. M. Cat. Ven. p. 32, no. 9.* This shell agrees in form and muscular impressions with Lucinopsis, but the teeth are those of Cyclina. The young shell is much more orbicular in form. I picked a valve from a col- lection of W. Indian shells which exactly resemble? this species in all respects except the anterior muscular impression, whick * Having just received the [type specimen of A. saccata, through the great kindness of Dr. Gould, I can speak to its exact identity. MAZATLAN BIVALVES 63 is somewhat nearer to the hinge, with the sinus less ascending. Epidermis extremely thin. Long. 1'51, lat. 1*54, alt. *8. Hab.St. Elena, West Columbia [?] very rare, Mus. Cuming. (Hani.) Panama, extremely rare ; C. B. Adams. Mazat- lan ; Lieut. Green. Mazatlan, extremely rare ; Lpool Col. Tablet 266 contains the largest specimen. GENUS DIONE, Megerle. Dione, B. M. Cat. Ven. p. 54. = Cytherea (maxima pars), Lam. Known by the smooth posterior teeth, ovate transverse form, and large horizontal pallial sinus. -V 92. DIONE AUEANTIA, Hani. Cytherea aurantia, Hani. Sp. of Shells, Append. : Wood Suppl. pi. 15, f. 20 .Sow. Thes. Conch, p. 228, pi. 132, f. 97 bis. Chione aurantia, Gray, Analyst, viii. 305. Dione aurantia, Desk B. M. Cat. Ven. p. 56, no. 3. Cytherea aurantiaca, Sow. Gen. f. 3. Itve. Conch. Syst. pi. 69, f. 3. Jay's Cat. p. 35. C. B. Ad. Pan. Shells, p. 272, no. 444. This magnificent and typical species appears to belong to the N. W. tropical province. The shape in regularity more nearly coincides with D. chione than with D. chiona3a. It is however larger and heavier ; less transverse, lunule less marked, and shewing a tendency to irregular concentric ridges of growth. The trifurcate white mark at the umbos has shorter and broader rays. The colour is a light salmon with occasional concentric bands of darker, in the young shell generally white at the margin ; covered with a uniform, rather thin, adherent, dark orange epidermis. Inside white, with purple stain on the liga- mental portion. Anterior adductor deeply impressed : the rest nearly as in D. chione. I have not been able to trace Sow.'s "obscure biangulato, &c." copied by Desh. Long. 3*62, lat. 4*28, alt. 2 '37. A specimen from S. W. Mexico is some- what larger. Hob. Gulf of Nicoyia, Jay. Taboga, very rare, C.B. Adams. South America [? ; non D'Orb. nee Cum.] ; Acapulco ; Desh- ayes. S. W. Mexico, P. P. C. Mazatlan ; Lieut. Green. Do. not common ; Lpool Col.*' * "Brazil; " Manchester Mus., without authority; probably an error. 64 MAZATLAN BIVALVES Tablet 267 contains 2 minute valves, the smallest '03, across, which may belong to this species. Tablet 268 contains 2 young specimens. 269, 2 sp. very large. 270, a distorted sp. with one valve overlapping. 271, another distorted sp. with a large anterior gape. 93. DIONE CHION^EA, Menlce* Cytherea chionaea, Menlce in Zeit.f. Mai. 1847, p. 190, no. 57. Cytherea squalida, Sow. Proc. Zool. Soc. 1835, p. 23. Hani. Descr. Cat. p. 104 : Wood's Swppl pi. 13, f. 40. Sow. Thes. Conch, p. 629, pi. 131, f. 87-89 C. B. Ad. Pan. Shells, p. 273, no. 447. Chione squalida, G-ray Cat. Cyth. Anal. 1838, viii. 306. Venus squalida, B. M. Cat. D'Orl. Moll. p. 68, no. 609. Dione squalida, Desk. B. M. Cat. Yen. p. 58, no. 6. 4- Cytherea biradiata, Qray, Zool. 'Beech. Voy. 1839, p. 151, pi. 43, f. 5. Siebold. in Wlegm. Arch. + Cytherea chione, pars, Sow. Thes. Conch, p. 629, no. 59. ? = Cytherea elegans, Koch, in Phil. Abbild. Conch. Cyth. 1844. p. 2 (150) pi. 1, f. 4. For a full description of the main features of this shell, v. Cytherea chione, Forbes Hani. Br. Moll. i. 3968, which applies in most of the minute particulars, even in that which is said to separate it, the 3 short ray-like colourless markings of which the central is the shortest, and the others margin the commencement of the lunule and the ligamental area. It is necsssary however to state, for the benefit of those who think * The learned have hardly behaved well to this exquisitely^beautiful species. It ./as first described from some Peruvian shells of a "very dull and dirty aspect," by 3ow., under the name (very inappropriate to the species generally) of C. squalida. ffe confesses however that one of the varieties is " rather agreeably ornamented was i Sow . Heconfes with concentric purple bands." The Masatlan shells were next described by Gray, in the Zool. Beech. Voy., as C. biradiata, a name applicable again only to a portion of the species. The East Indian shells were next named by Kofeh and described by Phil, in 1814 as C. elegans. Then Sow. jun. in*1851 gives in quo- tations (as though from the P. Z. S.) a fresh description of C. squalida, with only 6 of the original words, adding with singular inappropriateness "rubente- albicante radiata ; costellis numerosis, ooncentricis, obtusis, concinnis, confertis." He also tells us (an error which C. B. Ad. very politely exposes) that the species was first named from Philippine specimens brought by Mr. Cuming ; and also that the name C. biradiata in Beechey's voyage was given to the Philippine shells. Not content with these errors, he also informs us that Mr. Cumings a Mazatlan specimens belong to the Europeean C. chione. Last of all Menke gives the name C. chioneea to the Mazatlan species ; and though he only describes from a single specimen, it fortunately happens that both name and description are sufficiently comprehensive. As the prior names only apply to portions of the species, the ordinary rules of priority are disregarded in order to retain an expressive nams which includes the whole species. MAZATLAN BIVALVES 65 that Cythereae may always be known by the umbonal markings, that in this species they are extremely variable : the white rays take very different directions : or it is not rayed at all : or the white is entirely absent. The colour varies from dark lustrous brown to light grey : sometimes uniform, often biradi- ate with dark brown, generally more or less spotted in the young shell ; occasionally tinged concentrically with red, very rarely with purple or greenish, but never with the reddish chesnut which is very characteristic of D. chione. The inside also is often stained with violet, occasionally with yellow. The principal difference from D. chione is the shape, which is more swollen, almost subangulated in the posterior dorsal portion, the angular line generally ending in a produced posterior margin. These characters however are not constant. There is a spotted variety rather hard to distinguish from its W. In- dian analogue, D. maculata, not being less tumid (as Sow. states,) but rather more, and losing the posterior angulation. The pallial sinus in D. chione is generally denned by a some- what broader line, and is a little more pointed ; though I found the shape vary not a little in the many hundred specimens of D. chionaea which I have carefully examined. The East Indian specimens (if Philippi's figures are correct) have the ligament rather shorter, the lunule longer, and the pallial sinus less angulated. In other respects they exactly agree, and are considered identical by the very accurate Desh. ; not, of course, for geographical reasons, by C. B. Ad. If dis- tinct, they will take Koch's name of D. elegans. If I have rightly affiliated certain very small valves, the young shell (of which the smallest measures only *02 across) first developes the marginal teeth, leaving the central ones till it gets older. The anterior portion of the shell also is of abnor- mal size. The longest specimen measures long. 2*77, lot. 3*58, alt. 1'6. A transverse specimen 1*94, 2*54, 1*14. A rounded specimen 1*62, 1*87, 1*03. Hob. St. Elena, in sandy mud, 6 fm., Cuming. Ecuador ; St. Elena, D'Orbigny. Taboga, very rare, C.B.Adams. La Paz, Lieut. Green -S. W. Mexico, P. P. (7. Found abundantly at San Bias and Mazatlan, Lieut. Belcher. Mazatlan, common ; L'pool <$[ Havre Col. (D. elegans) Philippines, Cuming. Swan Eiver, N. H,, Philippi. Tablet 272 contains 11 small perfect and imperfect valves which probably belong to this species. MAZATLAN BIVALVES Tablet 273 contains 7 sp. of various ages, biradiate. 274, 2 do. gibbous. 275, 2 do. uniform dirk brown. 276, 1 do. trans- verse, very dark brown. 277, 6 do. and 2 valves, rather dark, not biradiate. 278, 6 do. light gray. 279, 3 do. very light, faint rays, young shell speckled. 280, 2 do. greenish tinge. 281, 1 do. purplish. 282, 4 do. concentrically banded with reddish. 283, 4 do. and a young valve, spotted, form like D. iiiaculata. !-- 94. DIONE EOSEA, Brod. fy Sow. Cytherea rosea, Zool. Journ. iv. 364. Zool. Beech. Toy. Moll. p. 151, pi. 43, f. 7. Hani. Descr. Cat. p. 104 : Wood's Suppl. pi. 9, f. 11. Phil. Abbild. Conch, p. 183, pi. 5, f. 6. Sow. TJics. Conch, p. 632, p. 132, f. 108. Dione rosea, Desk. B. M. Cat. Yen. p. 77, no. 71. Cytherea lepida, Chenu, Conch. HI. Shell as usual, either more or less produced posteriorly, or swollen ventrally ; but in all varieties known from D. lupinaria 1. by the non- development of spines, which alone might be accidental j 2. by the shape, which is much natter, and gener- ally more produced ventrally ; 3. by the colour, in which pink- ish brown rather than purple predominates, being uniform over the whole shell ; a white streak going along the line of spines without purple at the bases, and a brownish instead of purple patch covering the lunulax portion ; 4. by the anterior larninse, which instead of being close together, are only raised here and there, generally at intervals of 4 or 5 ; 5. by the longer ligament, which is enclosed by a finer ridge, scarcely conspicuous in one valve ; 6. by the absence of the line mark- ing the second row of spines and angulating the posterior margin ; 7. by the teeth which are less raised, more spreading. The colour within is white with diffused violet, no predominant at the hinge. Extremely rarely there is an attempt at the formation of a knob or two where the second row should be, but never a marking line. The concentric ridges are fine, nearly equal, and rarely evanescent ventrally. The ridge which bears the raised lamina does not necessarily bear the raised knobs. The ridges sometimes bifurcate, but are generally more parallel to the margin than in D. lupinaria. I have examined above 500 specimens, in which I believe the above characters are constant. A large number of them are pierced by preda- cious gasteropods. MAZATLAN BIVALVES 67 The largest specimen measures long. 1*97, lat. 2*38, alt. 1*06. A transverse specimen 1*72, 2*11, "87. JETab. Found abundantly at San Bias, Lieut. Belcher, (Beech. Voy.) Panama, Owning (teste Sow,. : non C. B. Ad.). Mazatlan ; abundant ; L'pool fy Havre Col. Tablet 284 contains a minute valve, probably belonging to this species, measuring '06 across. Tablet 285 contains 7 specimens, normal type. 286, 5 do. dark coloured, transverse. 287, 3 do., brownish tinge. 288, 3 do. laminao slightly raised ; the largest was attacked by a gasteropod, who left his hole unfinished. 289, 3 do. pinker shade. 290, 3 do. more produced ventrally. 291, 3 do. most produced. 292, 3 do. coarse ribs. 293, 3 do. very pale. \- 95. DIONE LUPINAEIA, Less. Cytherea lupinaria, Less. Cent. Zool. p. 196, pi. 64. Sow. Thes. Conch, p. 632, f. 111. Venus lupanaria, B. M. Cat. I? Orb. Moll. p. 67, no. 593. Chione lupanaria, Grray Anal. viii. 306. Dione lupanaria, Desk. B. M. Cat. Ven. p. 76, no. 68. Cytherea Dione, var. Brod. Proc. Zool. Soc. 1845, p. 45-6. Gray in Griff. Cwv. An. King. pi. 19, f. 1. Eve. Condi. Syst. i. 95. pi. 71, f. 1. Cytherea semilamellosa, G-aud. in Deless. Rec. pi. 19, f. 2. Chenu. Condi. III. pi. 9, f. 9. This shell is sometimes shaped like its well known W. Indian analogue, V. Dione, Lin. (Dione Veneris, Desk.) : but is almost always larger and more transverse. It is known at once by the concentric ridges, which are never sharp and raised as in D. Veneris, but either rounded or sub-obsolete on the ventral part. Many of them (generally every other, or 1 out of 3) become obsolete before reaching the anterior part ; the remain- der become sharply lamellar, gradually fading off to the lunule, not suddenly ending there as in D. Veneris. The posterior part has two angular swellings, one in the line of the inner spines, the other just beyond the ligament. The inner area, lunule and bases of spines are almost always purple even in the pale variety. There are all shades of colour from white to rich puse or purple. The spines appear very irregularly, sometimes two or more growing together, sometimes leaving a large space without. The young shell has always two rows, b MAZATLAN BIVALVES the inner one turned backward. In the adult, this row ceases. The very young shell has none ? while in D. Teneris they ap- pear much earlier. The spines in the large row are generally rather straight and very long; one measured long. 1*88, and others must have been longer when perfect. The concentric ridges are not always parallel with the margin of the shell, and often bifurcate very irregularly. I have examined carefully nearly 4,000 specimens, almost all of which had fallen victims to the voracious appetites of gasteropods, who drill their holes generally near the apex. Epidermis extremely thin : spines channeled. The spine of the smallest well marked specimen measures "41 ; the shell itself long. *49, lat. '59, alt. '31. The largest (without spines) 2 * 26, 2 ' 77, 1 ' 5. The most transverse 1'53, 2*06, 1*03. Hob. Salango, in sandy mud, 9 fm. ; Tumbez (Peru) soft mud, 5 fm. : Cuming. San Bias (Gulf of California), sandy mud, 7 fm., Col. Cuming. Payta, (Peru,) IfOrbigny. Mazatlan; Col. Jewett, (Gould ms.) Do j extremely abundant, L'pool # Havre Coll. Tablet 294 contains 2 minute valves, (the smallest '025 across,) which probably belong to this species, though they shew no trace of spines. Tablet 295 contains 9 very young specimens, rounder form, with rather coarser striae. 296, 6 do. rather older. 297, 3 do. adolescent. 298, 2 do. very large. 299, 9 very young, trans- verse form. 300, 8 do. rather older. 301, 6 do. adolescent. 302, 3 do. adult 303, 5 young, pale var. 304, 3 do. adult. 305, 4 sp. with extra spines. 306, 1 large do. shewing epidermis. 307, 3 young, spines forming at margin. 308, 3 do. spines strangely curved. 309, 2 do. small spine growing by and in broken large one. 310, 1 adult, with spurs on bottom of spines. 311, 1 do. two spines growing together. 312, 1 do. very crowded spines at margin. In all, 72 specimens. 96. DIONE P VULNEEATA, Srod. Cytherea vulnerata, Proc. Zool. Soc. 1835, p. 46. Hani Descr. Cat. p. W5.Catlow. Cat. p. 40, no. 116. Sow. Thes. Conch. p. 632, pi. 131, f. 95, 96. Dione vulnerata, Desk. B. M. Cat. Yen. p. 60, no. 15. Tablet 313 contains 2 minute opposite valves which may belong to this species. Hob. Eeal Llejos, in sandy mud, 6 fm. Cuming.? Mazatlan ; 2 valves off Spondylus ; L'pool Col. MAZATLAN BIVALVES 69 97. DlONE ? BEEVISPINOSA, Sow. Cytherea brevispinosa, Soiu. Thes. Conch, p. 632, pi. 132, f. 109. Dione brevispinata, Desk, in B. M. Cat. Ven. p. 76, no. 70. Tablet 314 contains a minute valve which may be the young of this species. It has close concentric rounded ribs, and very strong teeth for the size. Length "03. Hob. Gulf of California, Col. Cuming. ? Mazatlan, jun. 1 valve ; Lpool Col. 98. DIONE CIKCINATA, Born. Venus circinata, Born, Test. Mus. p. 61, pi. 4, f. 8. Chemn. Conch. Cab. vi. 312, pi. 30, f. 3Il.Dillw. Eec. Sk. i. 169. B. M. Cat. Sagr. Moll. p. 39, no. 474. Cytherea circinata, Sow. Thes. Conch, p. 631, pi. 132, f. 104-6. Forbes Hani. Br. Mol. i. 399. Dione circinata, Desk. B. M. Cat, Ven. p. 77, no. 72. Venus Guineensis, G-mel. Syst. Nat. p. 3270, &c. Cytherea Guineensis, Lam. An. s. Vert. ed. Desk. vi. 311, &c. Cytherea alternata, Brod. Proc. Zool. Soc. 1835, p. 45. Tablet 315 contains a small white valve which may be the young of this species : long. "08, lot. '095, alt. "05. Hal). Cuba, Sagra. S. Atlantic, Forbes. Mazatlan, Capt. Donnel : do. Lieut. Grreen, (Gould ms.) : do. one valve and fragments, jun., Lpool Col. Var. alternata, Monte Christi, in sandy mud, 11 fm., Cuming. 99. DIONE CONCINNA, Sow. Cytherea concinna, Proc. Zool. Soc. 1835, p. 23. Sow. Thes. Conch, p. 630, pi. 132, f. 99, 100. Dione concinna, Desh. B. M. Cat. Ven, p. 74, no. 61. Comp. D. affinis, Brod. Proc. Zool. Soc. 1835, p. 45 ; B M. Cat. Ven. no. 60 : and D. tortuosa, Brod. id. ; B. M. Cat. Ven. no. 62. This shell is coloured in sienna brown and white stripes in about equal proportions, the brown being darker on the ribs and in the lunule. Umbos yellow. Concentric ribs occasionally bifurcating. Pallial sinus, long, narrow, ascending. Long. 1*2, lat. 1'56, alt. '75. JIab. Panama, in fine sand, 10 fm. Cuming. Mazatlan ; 1 sp, with D. rosea ; Lpool Col. Tablet 316 contains the specimen. 70 MAZATLAN BIVALVES GENUS CYTHEEEA, Lam* Cytherea, ex parte, Lam. 1809, et auct. Meretrix, Lam. 1799 ; Desk. B. M. Cat. Yen. p. 34. This genus, as restricted, is known by tlie sub trigonal form, crenated posterior and distant anterior tooth, and the very small pallial sinus. 100. CYTHEEEA PETECHIALIS, Lam. Lam. An. s. Vert. ed. Desk. vol. vi. p. 299. Sow. G-en. f. L Hani. Descr. Cat. p. 96 : Wood Suppl. pi. 15, f. 9 five. Conch. Syst. vol. i. pi. 69, 70, f. 1.? Sow. Thes. Conch, p. 619, pi. 129, f. 51. Meretrix petichialis, Enc. Meth. pi. 268, f. 5, 6. Desk. S. M. Cat. Ven. p. 36, no. 4. The widely extended form to which this shell belongs was distributed by Lam. under the species lusoria, petichialis, im- pudica, castanea, zonaria var. 1, meretrix and graphica. Desh. in his edition of Lamarck regarded the 6 last, and C. lusoria probably, as all varieties of one species, differing only in colour, and displaying insensible gradations even in this. In the B. M. Cat. Ven. however he publishes them all as distinct (ex- cept meretrix which is merged into M. impudica), along with C. fusca, Koch in Phil. Amid. Conch, p. 19, pi. 3, f. 1. Sow. unites C. graphica with C. petichialis, C. fusca with C. lusoria, C. castanea with C, impudica, adding C. formosa on his own authority, and yet "being almost persuaded that" all these, along with C. meretrix, morphina, zonaria, casta and ovum Hani., "might be united under one name, seeing that they pass imperceptibly into each other, and that in a young state it is almost impossible to distinguish them." If the varieties would arrange themselves into zoological provinces, there would be more hope of finding specific types ; butl am unable to find any difference between the Mazatlan shells and those from the China and Japan seas. I found scarcely a dozen specimens in the D. chionsea box of the Liverpool collection ; but several more were seen mixed with the other Mazatlan shells in the shop of a dealer who had surreptitiously obtained * The familiar Lamarckian name ("nom plus convenable," Lam.) is retained, because a man ought to be allowed to alter his own work if he can improve it ; as he certainly did in this instance, by rejecting a meretricious name for so beau- tiful a group of shells. There is nothing unchaste in nature : it is only man's corrupt ideas that see unclean images in the purity of God's works. MAZATLAN BIVALVES 71 no inconsiderable a portion of the collection.* These shewed great diversities of colouring ; sometimes abounding in the typical dots, sometimes shewing the faintest traces of them. The dots were scarcely ever angulated, according to the de- scription and figures of Sow. The favourite trifurcate white mark at the umbos sometimes darts up long angular rays ; in other cases it is extremely small and irregular. Long. 2*5, lat 2*9, alt. 1*4 Hob. Indian ocean, Lamarck. China, Deshayes. [? C. gra- phica] Japan, Dr. Sibbald, Mus. Cuming. Mazatlan, very rare; L'pool CoL Tablet 317 contains 5 young valves, from the Chama and Spondylus washings, the larger of which I think certainly, the rest perhaps, belong to this species. Tablet 318 contains 2 adult specimens, one of which at least was from the box. GENUS VENUS, Linn. Venus, ex parte, Linn., Lam., et auct. Chione, Megerle, 1811 ; Gray, 1847 ; Desk. B. M. Cat. Yen, p. 118; (non Gray, 1838.) 101. VENUS (CHIONE) GNIDIA, Brod. fy Sow. Venus gnidia, Zool. Journ. iv. 364. five. Conch. Syst.. pi. 68, f.6?Graym Zool. Beech. Voy. pi. 41, f. 3 . tieless. Rec. de Coq. pi. 19, f. 1, a, I Hani. Descr. Cat. p. 113, pi. 13, f. 43 : Wood's Suppl. pi. 13, f. 43. Sow. Thes. Conch, p. 709, pi. 154, f. 25. B. M. Cat. D'Orb. Moll. p. 68, no. 606. C. B. Ad. Pan. Shells, p. 269, no. 437. Chione gnidia, Desk, in B. M. Cat. Ven. p. 132, no. 41. This queen of Veneres nourishes in the greatest luxuriance and magnificence in the Mazatlan seas. Though the texture is not so delicate as that .of Ch. amathusia, nothing can exceed the beauty of the concentric frills, which rise at various intervals generally perpendicular to the surface of the shell. On the back, they carry off the radiating furrows.: on the front they are beautifully crenated. They generally rise into laminae (sometimes '23 long) which are occasionally bent up almost * Before I knew how much the species was divided, I distributed under this name in several of the Mazatlan collections (" Hab. incog.") specimens whicfo properly rank under one of the other groups. 72 MAZATLAN BIVALVES into a tube. The epidermis is extremely thin, but important to preserve the shell, which soon becomes of a calcined appear- ance without it. The radiating striae become obsolete in the old shells, but not so much so as in Ch. amathusia. The smallest valve measures *03 in length : the largest specimen, long. 3*5, lot. 3 '56, alt. (without spines) 2*3. Hob. Payta, Peru, Fontaine, D'Orbigny. Panama, rare, C. B. Adams. San Bias, Jay. Mazatlan ; Lieut. G-reen, (Gould ms.) ; extremely abundant ; I! pool fy Havre Coll. Tablet 319 contains 3 very young valves. 320, 4 young specimens, form somewhat rounded. 321, 3 do. adolescent. 322, 3 do. adult. 323, 3 young, slightly produced 324, 3 do. adolescent. 325, 2 do. adult, ribs close. 326, 3 do. young, more produced. 327, 2 do. adult. 328, 4 young, rather flat- tened, with distant laminae. 329, 3 do. adolescent. 330, 2 do. adult. 331, 5 young specimens set to shew the ventral margin in different stages of growth. 332, 4 do. adolescent. 333, 4 do. adult. 334, 2 sp. shewing the nearest approach to Ch. amathusia, and unnatural longitudinal grooves. 335, 1 sp., ribs not foli- ated ventrally. 336, 2 do., ribs flattened. 337, 1 do., strongly foliaceous. 338, 1 do., foliations semispinous. 339, 1 sp. de- formed growth. 340, 3 do. with irregular ribs. In all 59 specimens. 102. VENUS (CHIONE) AMATHUSIA, Phil, Venus amathusia, Phil. AbUld. p. 129, pi. 2, f. 4. C. B. Ad. Pan. Shells, p. 269, no. 435. Sow. Thes. Conch, p. 709, pi. 154, f. 26, 27. Chione gnidia, var. Desk. B. M. Cat. Yen. p. 133, no. 41. + Chione amathusia, Desh. do. p. 132, no. 39. ?= Venus cancellata, MenJce in Zeit.f. Mai. 1847, p. 191, no. 58, (non Lam.) ?= Venus succincta, Vol. in Humb. Rec. d'Obs. vol. ii. I follow Hani. Sow. and ? C. B. Ad. in regarding this as Philippi's species. It agrees exactly with the description ; not with the figure. I have however a very worn young stumpy specimen from S. W. Mexico, which is sufficiently like the figure, especially when it is remembered that figures are not always like the shell. I cannot say that I should have known it even from Sow.'s figure, which is much better. Desh. re- gards Phil.'s species as distinct, and (with Dr. Gray) considers this a variety of Ch. gnidia. What changes the creatures make MAZATLAN BIVALVES in other places I do not know, except from the picked speci- mens in Mr. Cuming's Col. He regards the species as distinct. The Mazatlan shells would never have encouraged any one to unite them : neither Collector nor dealers offered to put them together. I have very narrowly examined about 400 specimens of this shell, and more than 600 of Ch. gnidia, nor did I find a single intermediate form. The texture of the shells varies as earthenware from china ; Ch. amathusia under the epidermis being glossy, and of a very light brownish purple ; Ch. gnidia in the same circumstances having the appearance of a baked shell, dull, and of a darker brown. The concentric ribs are peculiarly lustrous, and are very short and stumpy, rarely shewing any tendency to rise into scales. The radiating stria? are very much fainter, shewing a disposition to gather in twos in the young shell. The lunular portion is much larger, smoother, and of a richer purple. Both species within shew the middle teeth slightly furcate, the paliial line distant from the margin, and the sinus small. Ch. amathusia is generally smaller, more swollen, with a thicker shell and margin ; and is more angula- ted posteriorly. It is represented by Ch. cancellata in the Caribbean sea, and its young may be the shell so named in Menke's Mazatlan list. The smallest specimen found is 1*5 in. long ; the largest measures long. 2*43, lot. 2 '74, alt. 1'63. JTab. ? Panama, very rare, C. IB. Adams. S. W. Mexico, P. P. C. Mazatlan ; Lieut. Green, (Gould ms.) Do. ; com- mon and very fine ; L'pool fy Havre Coll. Tablet 341 contains 3 specimens, rounded form. 342, 3 do. more angulated. 343, 3 do. close ribs. 344, 3 do. produced posteriorly. 345, 3 do. distant ribs. 346, 3 do. swollen form. 347, 3 do. produced. 348, 3 do. even growth. 349, 1 do. witli irregular ribs. In all 25 specimens. 103. VENUS (? CHIONE) , sp. ind. This can scarcely be the young of Ch. amathusia, since the shape is very different, being subquadrate. Surface more or less distinctly marked with fine concentric ridges and radiating striae, sometimes nearly smooth ; luuule clearly marked ; an- terior tooth rather long; paliial line distant from margin; sinus broad, shallow. Colour pink or light green. The largest specimen measures long. '09, lot. '12, alt. '06. Oct. 1855. h 74 MAZATLAN BIVALVES Hal. Mazatlan ; about a score were found in the dirt from the small Olivae ; L'pool Col. Tablet 350 contains 4 pairs decussated. 351, 1 pair and a valve, concentric ridges predominant. 352, 2 pairs, nearly- smooth. 104 VENUS (? CHIONE) DISTANS, Phil. Venus distans, Phil, in Zeit.f. Mai. 1851, (Cassel 1852) p. 126. ? Chione distans, Desk. B. M. Cat. Yen. p. 123, no. 13. Tablet 353 contains a worn valve, with 2 stout concentric ridges, which comes nearest to this species. Length "07. JIab. Panama, E. . Pkilippi.? Mazatlan, 1 valve off Spon- dylus ; L'pool Col. 105. VENUS (CHIONE) CKENIFERA, Sow. Venus crenifera ; Proc. Zool. Soc. 1835, p. 43. Hani. Descr. Cat. p. 118 : Wood Suppl. pi. 16, f. 30.5. M. Cat. DOrb. Moll. p. 67, no. 603. &w. The*. Conch, pt. 14, pi. 156, f. 73, 74. Chione crenifera, Desk. B. M. Cat. Ven. p. 136, no. 50. ? = V. elevata, Say teste Sow. ?=V. radiata, Chemn. t. 36, f. 386, teste Sow. =V. portesiana, D'Orb. Voy. Am. Mer. Moll. p. 556, pi. 83 y f. 1, 2, teste Desk. This shell belongs to a group of closely allied species, one of which is from the W. Indies. I am not sure that it is rightly named, but I follow Mr. Reeve's authority. It fits the original description, as others might, but not the figure or notes in Sow.'s Thes. Conch. The radiating lines scarcely ever group in threes ; the shape is suboval, scarcely beaked ; the dorsal area is nearly smooth in one valve, but with the concentric ridges continued over in the other, which overlaps beyond the liga- ment. Surface very irregularly spotted with light chocolate brown. Concentric ridges (which are more or less close) strongly indented and rather glossy. Pallial sinus small, sub- oval. Anterior tooth prolonged, sharp : cardinal, sub-bifid. Largest specimen (worn) measures long. 1*64, lat. 1*87, alt. 1*08. Sab. St. Elena, in sand at low water ; var. Payta (Peru) ; Cuming.Payt&, D'Orligny. Mazatlan : extremely rare ; L'pool CoL MAZATLAN BIVALVES 75 Tablet 354 contains a minute valve, long. '05, and some frag- ments. 355, the most characteristic specimen. 106. VENUS (CHIONE) ? UNDATELLA, Sow. Venus undatella, Proc. ZooL Soc. 1835, p. 22. Hani. Descr. Cat. p. 117. Sow. Thes. Conch, p. 711, pi. 153, f. 22. Chione undatella, Desk. B. M. Cat. Yen. p. 141, no. 68. Tablet 356 contains a broken very young shell which may belong to this species. Concentric ridges numerous ; radiating costa3 just beginning to shew near margin : anterior tooth pro- longed, as usual in young shells. Long. "04. Hab. On the shore, Isle Tres Marias, Gulf of California ; Col. Cuming. PMazatlan; 1 valve, off Spondylus ; L'pool Col. JL 107. VENUS (CHIONE) COLUMBIENSIS, Sow. Venus Columbiensis, Proc. Zool. Soc. 1835, p. 21. Hani. Descr. Cat. p. 119 : Wood Suppl. pi. 16, f. 2. Sow. Thes. Conch, p. 713, pi. 155, f. 53, 54 B. M. Cat. D Orb. Moll. p. 68, no. 611. Chione Columbiensis, Desk. B. M. Cat. Ven. p. 136, no. 53. Shell remarkably solid, with, strong ligament ; with deep radiating grooves leaving broad flattened ridges which are crossed by fine concentric ridges, slightly elevated, rising and falling with the furrows, rather irregular, evanescent on the ventral portion, and nearly so on the posterior, where the ribs often rise into scales on the line of the ridges. The shells often show here and there concentric risings of growth, the fresh shell being commenced below the other. In one valve the posterior rib is very large, overlapping the other valve beyond the ligament. Lunule defined by a deeply cut line, swollen in the middle, and bent at the margin. In these points, and in the character of the hinge, this species closely resembles Ch. verrucosa ; the pallial sinus however is somewhat larger. In more than half the specimens, the prevailing colour is choco- late brown ; in the remainder, yellowish white more or less tinged with patches of purplish brown. The young shell is very often white, tipped at the umbos with pink or brownish purple. The smooth ligamental area is always spotted with purple. In the very young shells [?] the concentric ridges are not seen ; afterwards they often go nearly across. Colour inside, white, 76 MAZATLAN BIVALVES often purple, especially on the hinge line. The smallest valve is "03 across ; the largest measure? long. 1*9, lat. 2*, alt. I' 28. Hob. St. Elena, in coarse sand at low water, Cuming. Ecuador ; St. Elena, D'OrUgny.$. W. Mexico, P. P. C Mazatlan ; extremely common ; L'pool fy Havre Coll. Tablet 357 contains 7 young valves, [?], lunule not defined, very faint concentric lines of growth, anterior tooth elongated, as is usual in young Veneridse. Tablet 358 contains 7 specimens of the normal chocolate colour. 359, 7 do. with white umbos. 360, 7 do. purplish tinge. 361, 7 do. light coloured, slightly spotted. 362, 7 do. with large patches of dark. 108. VENUS (? CHIONE) , sp. ind. Tablet 363 contains 3 small valves, the smallest only '02 across, smooth and white, which do not accord with any of the foregoing species. Hob. Mazatlan ; in shell washings : L'pool Col. GENUS TAPES, Megerle. This genus, though the type of a sub-family of Gray, (B. M. Cat Ven., p. 159) approaches Venus (Chione, Megerle, Grray,) by insensible gradations. The following species may be ranked with either genus. The typical forms have not yet been found in this Zoological province. 109. TAPES HISTRIONICA, Brod. fy Sow. Venus histrionica Proc. Zool. Soc. 1835, p. 41. Hani. Descr. Cat. p. 119 ; Wood. Swppl. pi. 16, f. 31. B. M.^ Cat. D'Orb. Moll. p. 67, no. 594 Sow. Thes. Conch, p. 714, pi. 55, f. 52. Chione histrionica, Desk. B. M. Cat. Ven. p. 139, sp. 60. Tapes histrionica, Hani. Col. suo. This belongs to a group of very closely allied species, of which T. granulata (B. M. Cat. Ven. p, 138,) is the W. Indian analogue, and T. straminea the Calif ornian. It has the form and sculpture of a Tapes, with the teeth and pallial sinus of a Venus. The form varies in the greater or less development of the posterior angle, and in the flattening or rounding of the MAZATLAN BIVALVES 77 ventral margin. The colour is very light brown, more or less spotted or stained with darker in zigzag stripes or blotches. The ligamental area is smooth, and marked off by a decided keel on each side. The keel is almost always painted with spots, even when the rest of the shell is without them. Long. 1*34, lat. 1*58, alt. '8. Hob. Real Llejos & St. Elena, in muddy sand at low water, Cuming. Ecuador, St. Elena, D' Orlngny. Mazatlan ; ex- tremely abundant ; L'pool fy Havre Coll. Tablet 364 contains 7 specimens with dark patches of brown. 365, 7 do. smaller patches. 366, 7 do. very small patches. 367, 7 do. dark markings obsolete. 368, 7 do. with generally diffused shade of lighter brown. 369, 7 do. the same broken up into patches. 110. TAPES GEATA, Say. Sow. TJies. Conch, part 13, p. 699, pi. cli., f. 152 : (non Desk, in J5. M. Cat. Yen. p. 170.) Venus grata, Say Am. Condi. 1830, pi. 26 (teste Jay, 36 teste Sow.) Chione grata, Desk, in J9. M. Cat. Ven. p. 140. = (teste Desh.) Venus tricolor, So^v. Proc. Zool. Soc. 1835, p. 41. Zool. Beech. Voy. p. 151, pi. 41, f. 7. Hani. Descr. Cat. p. 119 .- Wood Swppl. pi. 16, f. 32. (Tapes t.) Sow. Thes. Qonch. p. 699, pi. 151, f. 153. = (teste Jay) Venus discors, Sow. Proc. Zool. Soc. 1835, p. 42. Hani. Descr. Cat. p. 118 : Wood Suppl. pi. 15, f. 603. M. Cat. DOrb. Moll. p. 67, no. 600. C. B. Ad. Pan. Shells, p. 269, no. 436. (Tapes d.) Sow. Thes. Conch, p. 698, pi. 151, f. 148-150. (Chione d.) Desh. B. M. Cat. Ven. p. 141, no. 65. ? = Venus Entobapta, Jonas Zeit.f. Mai. 1845, p. 66. ?= Venus- neglecta, Phil. Abbild. ii. 62, pi. 4. f. 3, (non Gray.) This shell differs from T. histrionica in not having the smooth ligamental area nor the enclosing carinse. The lunule also is less distinct. The large specimen is much more tumid, and more irregularly marked. The hinge teeth are much closer and smaller in proportion, and are very slightly bifid. Pallial sinus less angulated, smaller. Internal crenations less distinct. An intermediate specimen has one tooth in each valve strongly bifid, and is flattened like T. histrionica. The youngest speci- men scarcely displays bifidity, is much more coarsely and regularly marked, and has the pallial sinus rounder. It is MAZATLAN BIVALVES possibly a distinct species, and closely resembles the W. Indian T. gramilata. The largest measures long. 1*5, lat. 1'66, alt. 1'06. Hab.W. Coast Mexico, Say. S. W. Mexico, P. P. 0. Mazatlan, 3 specimens with T. histrionica, L'pool Col. (T. discors) St. Elena and Guacomayo, in sandy mud, 6-9 fm., Cuming. Ecuador, St. Elena, D'Orbigny. Panama, Jewett, (Gould ms.) ? Do. : common, C. B. Adams. Guaymas, Lieut. Green, (Gould ms.). (T. tricolor) Puerto Portrero, in sandy mud, 11-13 fm. Cuming. Tablet 370 contains the small specimen ; and 371, the largest. 111. TAPES SQUAMOSA, n. s. T. t. parvd, subquadratd, oblonffd, alba fusco maculatd ; margine dorsali subrecto, postice angulato ; costis fortibus ab umbone prominente radiantibus, liris concentricis parte anteriori etvenlrali decussatis ; parte posteriori liris obsoletis, costis ibi interruptis, squamosis , maxime costd lig amento proximo, ; dentibus 2-3 cardinalibus divergentibus ; sinu pallii subovali ; lunuld impressd. E,emarkable for the strong radiating ribs, broken up into scales posteriorly which are very large on the rib next the ligament. On the body of the shell these are decussated with moderately distant raised concentric lines. The young shell has in one valve a long posterior lateral tooth close to the liga- ment. This shell measures long. '03, lat. *04; the largest valve long. '09, lat. '115, alt. "05. Sab. Mazatlan ; from washings of Chamse and Spondyli ; extremely rare ; Upool Col. Tablet 372 contains the only 3 valves found. GENUS ANOMALOCAEDIA, Klein. ' Anomalocardia, Sckum. 1817, Essai d'une Meth. p. 134. Desk. B. M. Cat. Yen. p. 115. Triquetra, Blainv. 1818. Cytherea, sp. Lam. Venus sp. Sow. Phil. &c. This small group of Yeneridse, consisting of species classed sometimes with Yenus, sometimes with Cytherea, is well char- acterized by its irregular growth and extremely small pallia! sinus. MAZATLAN BIVALVES 79 Hh 112. ANOMALOCARDIA SUBEUGOSA, Sow. Venus subrugosa, Sow. Gen. f. 2. Eve. Conch. Syst. i. pi. 67, f. 2. Hani. Descr. Cat. p. 116 -Wood Suppl. pi. 2, f. 6. Phil. Abbild. Conch, p. 177, pi. 3, f. 6, 7. Sow. Thes. Conch. p. 721, pi. 155, f. 63. .B. M. Cat. D'Orb. Moll. p. 67, no. 595. C. B. Ad. Pan. Shells, p. 271, no. 440. Anomalocardia subrugosa, Desk. . M. Cat. Yen. p. 116, no. 2. = Cytherea subsulcata, Menlce, in Phil. Abbild. (ad fid. spec, ab ipso accept.) This very variable shell is represented on the Atlantic coast by A. flexuosa. It is very coarse and heavy ; generally worn at the umbos. The earlier part of the shell is covered by irregular concentric swellings, which afterwards become eva- nescent on the ventral portion, sometimes all over. These are crossed by rather deeply cut fine radiating lines, which are generally strongest in the depression which marks off the posterior beak, rarely becoming punctato-striate. This depres- sion however often nearly disappears, and the shell approaches A. subimbricata in form. Sometimes it is much flattened, some- times remarkably swollen and gibbous ; sometimes very trans- verse, sometimes much produced ventrally. The radiating grooves sometimes cover the flattened ventral margin, which is very finely crenulated within. The lunule is marked by a well-defined line, and nearly smooth. The teeth and ligament are very strong. Colour generally a yellowish or brownish white,' almost always with 2-4 (generally 3) more or less broad radiating brown stripes ; and the rest often freckled with dots or broken lines. Inside generally with a purple stain about the hinge. Epidermis very thin, very pale or brownish. A transverse specimen measures long. 1*3, lot. 1*72, alt. '88. An elongated 1'49, 1*78, 1. A thick 1-48, 1'88, 1'2. Sab. Panama, Hanley. Peru, Tf Orbigny. Panama ; partly buried in coarse sand among stones or under trees, near half tide level, rare ; C. IB. Adams. -S. W. Mexico, P. P. C. Mazatlan ; in extreme profusion ; L'pool fy Havre Coll. Tablet 373 contains 1 minute valve "6 across. 374, 6 young specimens, usual state. 375, 6 do. adult. 376, 6 do. more beaked. 377, 6 do. more swollen, produced ventrally. 378, 2 do. shape of A. subimbricata. 379, 6 do. more transverse. 880, 3 do. very tumid var. rounded. 381, 6 do. more trans- verse. 382, 4 do. beaked. 383, 5 do. flattened var., produced 80 MAZATLAN BIVALVES ventrally. 384, 6 do. rather beaked. 385, 4 do. more trans- verse. 386, 7 do. transverse form, beak not indented. 387, 6 do. very transverse and indented. Groups shewing colour. Tablet 388 contains 2 sp. whitish var. normal. 389, 2 do. trans- verse. 390, 2 do. flat. 39.1, 2 do. tumid. 392, 3 sp. yellowish var. normal. 393, 3 do. transverse. 394, 2 do. rounded. 395, 1 do. tumid. 396, 3 do. orange var 397, 3 sp. dark var. nor- mal. 398, 3 do. elongated. 399, 3 do. rounded. 400, 3 do. tumid. 401, 3 do. form of A. subimbricata. ^402, 3 sp. broad bands. 403, 3 do. speckled. 404, 3 do. narrow bands. 405, 2 do. and a valve, bands very faint. Tablet 406 contains 3 sp. strongly rugose. 407, 3 dp. smooth form. 408, 3 do. shewing the inside. In all 130 specimens. 4 113. ANOMALOCAKDIA SUBIMBRICATA, Sow. Venus subimbricata, Proc. Zool. Soc. 1835, p. 21. Wood Su/ppl. App. pi. 15, f. 57. Sow. Thes. Condi, p. 711, pi. 154, f. 35-38. Anomalocardia subimbricata, Desk. B. M. Cat. Yen. p. 117, no. 4. Only a very few small pairs and some young dead valves were found of this species, which further south is not uncom- mon. These few however exhibited remarkable differences. Sometimes the form was regular, sometimes extremely gibbous. Sometimes the concentric folds were rounded ; sometimes as though the shell was raised at intervals and a fresh shell begun below ; sometimes the radiating ribs were crossed by angular laminae, as in Ch. amathusia and gnidia. In this state it may possibly be the V. cancellata of Menke's *Maz- atlan catalogue (Zeit. f. Mai. 1847, p. 191) ; unless indeed that be a young specimen of one of the species above named, from which it may be told by the extremely minute pallial sinus. Very rarely the concentric ridges scarcely appear in the young shell, in which state it might easily be taken for another species. In one very young specimen, on the other hand, the concentric folds are sharp, while the radiating ribs are nearly evanescent. The largest specimen only measures long. I'M, lat.l'l, alt. '77. Hab. Puerto Portrero, in fine sand, 13 fml Cuming. Acapul- co, Sowerby. S. W. Mexico, not uncommon, P. P. C. Mazatlan ; extremely rare ; L'pool Col. Tablet 409 contains 2 minute valves. 410, 5 valves of various forms. 411, the gibbous specimen. MAZATLAN BIVALVES 81 FAMILY ASTAETID^, Cyprinidse, Forbes, Woodw. This name has been previously appropriated for a family of Fishes. Gray divides it into four families, Carditidse, Astartidse, Crassatellidse, and Glos- sidse (Isocardia, Lam.) GENUS CIECE, Sckum. Cytherea (pars) Lam. This genus is ranked with the Veneridse by Gray fy Desk., with As tart e and Cyprina by Forbes and Woodw. -f ' 114. ClKCE MAKGAEITA, ft. S. C. t. minima, subovali, incequilaterali, umbonibus appressis, subrugosis, concentrice liratd, liris acutis, area lunuldque indistinctis, ligament o celato : parte anteriori dilatd, posteriori parvd ; dente laierali antic o maximo, alterd in valvd in cardinalem confluente ; postico longo, exili : cardinali- bus 2-3 : impressionibus muscularibus, sub&qualibus, lined pallii d margine remotd ; albd flavescente, dentibus pwrp&reis ; epi- dermide tenui. This genus abounds in the Red Sea, Australia and the East Indies generally. It has not been described from the American coast. I have several species -in a collection sent from the U. S. as from S. America ; but as nearly all are identical with Aus- tralian species, the locality is probably erroneous. The charm- ing little C. margarita however establishes its claim to a place in the genus, by its appressed, somewhat rugose umbos, semi- internal ligament, large anterior tooth, and the pallial line which, though generally indistinct, is certainly not sinuated. It is oval, with very delicate, rather sharp concentric lines, covered with a thin epidermis ; sometimes subdiaphanous, sometimes opaque and yellowisli inside, with a purple tinge on the teeth. It may be the young of a larger species not yet discovered, but as about a score of specimens were found fresh, nearly of the same size, and with the rugose portion of the umbos clearly distinguished, it may not improbably be adult. Long. "05, lat. '07, alt. '03. Hab. Mazatlan ; on Spondylus Lamarckii, very rare ; L'pool Col. Tablet 412 contains 1 pair closed ; 2 do. open, (the largest and smallest,) and 1 yellowish valve. 82 MAZATLAN BIVALVES .L 115. PClfiCE SUBTBIGONA, *?. S. C. t. parvd, subtrigond, po slice longius, margine ventrali ovali ; concentrice tenui ssime striatd; umbonibus ap- pressis, subrugosis ; ligamento celato ; dentibus lateralibus posticis magnis, anticis subapproximatis ; impressionibus muscularibus d margine distantibus ; albo-lutescente, macula, fu sea post ice, intus subrugosa, et lineis divaricatis hue et illuc pictd ; epidermide tenui. Known at once from C. raargarita by its shape which is longest behind ; by the very fine concentric strise ; the large posterior tooth (not so large however proportionally as the anterior tooth of C. margarita ;) and the painting, which dis- plays a large irregular brown patch inside, which projects somewhat above the regular level and is slightly rugose, and a few irregular zigzag lines on a yellowish white ground. I have not been able to trace the pallial line. There is no trace of sinus, though the colour markings sometimes give an erroneous appearance of it. In other respects the generic characters are satisfactorily marked. It is somewhat less uncommon than C. margarita, though I found very few fresh specimens. This greatly exceeds it in size. Long. '08, lat. ' 11, alt. *04 Hob. Mazatlan ; on Spondylus Lamarckii, rare ; L'pool Col. Tablet 413 contains 2 minute valves, cardinal teeth not formed ; 2 adolescent and a pair united ; and 2 valves adult. GENUS GOULDIA, C. B. Adams. As I have neither had the good fortune to find the original diagnosis of this genus, nor to meet with any conchologist who understood it, I can only guess what it was meant to include. The late learned and very accurate Prof. Adams, in his descrip- tion of the following species, gives no account of the teeth. Fortunately however Mr. Cuming possesses and has allowed me to examine type specimens of G-. parva and Pacifica, received from the Professor. The former bears a general resemblance to our ? Circe minima : the second is undoubtedly the Mazatlan shell, and is like an Astarte with lateral teeth, such as occur in not a few of the Crag species. A third species is now added, from its general agreement with the second. MAZATLAN BIVALVES $3 116. GouLDiA PACIFICA, C. S. Ad. C. S. Ad. Pan. Shells, p. 275, no. 450. The only pair found (and that imperfect) was unfortunately smashed just after it had been sketched, It was of a rich lus- trous brown like Petricola robusta. The shell has all shades to a dingy white. About 18 odd valves were found, by no means constant in their characters. The general appearance is remarkably like a little fossil Astarte noticed in a communi- cation made to the British Association, L'pool, 1854, (v. Re- port, p. 78,) flat, triangular (in that respect alone like Tellina Burneti) and with very distant ribs outside. These ribs are generally sharp, but sometimes rather flat and rounded. The anterior dorsal margin is concave in young specimens. The surface of the shell appears under the glass, covered with fine radiating striae ; but under the microscope these lines are found to be simply the divisions between rows of parallel oblong dots, which most resemble the strung figs of commerce, and are laid in rows, side by side, over the surface of the shell. These show through in very young specimens, and present a most beautiful appearance. Inside, one valve has a long anterior lateral tooth, a short distant posterior one, an<^ 3 nar- row divergent cardinal teeth, of which the middle one lies between two broad pits, and the anterior joins on to the lateral. The other valve displays a long posterior, and small distant anterior lateral ; with 3 cardinals, of which one is the beginning of the posterior lateral, the middle rises between two pits, and the anterior is marginal, nearly obsolete. Muscular and pallial marks distant from margin. The largest valve measures long. '16, lat. 'IS, alt. *05. Hob. Panama ; not common ; C. IB. Adams. Mazatlan ; off Chamse and Spondylus, very rare ; L'pool Col. Tablet 414 contains 4 valves, of different ages, and a fresh fragment to shew the * strung-fig' structure. j 117. GOULDIA VAEIANS, n. s. G. t. minima, subtrigoqd, subcequilaterali, forma plus minusve angulato-rotundatd, plus minusve elongatd; albidd, plus minusve fusco maculatd; subleevi, striis incrementi, sive costis concen~ tricis paucis seu numerosis ; superficie lineis granulosis radi- antibus creberrimis ccelatd ; umbonibus subspiralibu-s, haud conspicuis ; margine simplici, appresso ; dentibus lateralibus 84 MAZATLAN BIVALVES alterd valvd postico, alterd antico magnis, longis ; cardinalibus 3-3, quarum medius alterd valvd Minimus, alterd maximus ; im- pressionibus muscularibus subrotundatis, lined pallii a margine distantiore. Four or five well characterized species might easily be de- scribed from extreme forms of this variable little shell. Like one of the Crag fossil Astartidse, it has concentric ribs either near the umbo, all over the shell, or not at all. Sometimes in forming lines of growth, it leaves a sharp projecting ridge. Sometimes it is of a somewhat regular Venus shape (especially when young) ; sometimes it is narrowed and unusually pro- longed. Even in its most ribbed form, it differs from Gr. pacifica in being very much smaller, not so flat, with umbos more spirally projecting, and with the anterior dorsal margin less concave, as well as in having the ribs smaller, and closer. It has the general size and appearance of Astarte triangularis. The colour is generally whitish, with a large anterior brown stain. The teeth are on the plan of Gr. pacifica, but display specific differences in their comparative size. The surface under a high power displays the strung-fig pattern, but on a very much finer scale than in Gr. pacifica. Underneath the outer layer, the shell is somewhat granulose. About a score of pairs and more than 200 single valves were found on the large shells. It was not noticed by C. B. Adams at Panama, but it probably finds its way as far South, as I found it on specimens of Murex regius said to. come from that place. The smallest specimen measures long. '03, lat. '035, alt. '015. The largest '09, '08, '05. Hab. Mazatlan ; common in shell washings ; L'pool Col. Tablet 415 contains 1 pair and 12 valves ribbed. 416, 4 valves ribbed near the umbos. 417, 6 valves, nearly smooth. 418, 5 valves regularly rounded. 419, 5 valves elongated. GENUS CAEDITA, Brug. \~ 118. CAEDITA CALIFORNICA, Desk. Proc. Zool. Soc. 1852, p. 100. ? = Cardita affinis, MenJce in Zeit. f. Hal. 1847, p. 188; et Gould ms. : non Sow. As this is the northern form representing the more tropical C. affinis (Sow. Proc. Zool. Soc. 1832, p. 195 ; v. also C. B. Ad. Pan. Shells, p. 264) it is probably the shell quoted as C. affinis MAZATLAN BIVALVES 85 by Menke in his list of Melchers' Mazatlan shells, and by Gould as collected by Lieut. Green at Guaymas. I have C. affinis from S. W. Mexico ; but all, even the most minute, specimens from the Mazatlan collection belong to this species. C. Californica differs from C. affinis (as far as my few speci- mens enable me to judge) in being rather less transverse, less incurved at the anterior ventral part, less narrow and projecting anteriorly, with the ribs rounder, larger, and covered with very large scaly protuberances at the posterior end. The colour also is much redder, and the epidermis lies in much finer concentric lines. C. Californica begins life in an irregular way without ribs, as a tiny white creature with concentric striae. The ribs how- ever on appearing soon become very large and well armed. The creature then looks like a tiny Tridacna, with extremely projecting umbos, sub trigonal, and nearly equilateral. At this time there is a large, distant, anterior lateral tooth. (There seems a general tendency among bivalves, in their earliest stage, to an abnormal development of the anterior portion. Pis the foot then more active than the siphons. Gradually the posterior part grows, the colour appears, and the anterior tooth draws nearer (proportionally) to the hinge. There are generally one or two fewer ribs developed in -the young than in the adult. The smallest specimen is '03 across ; the largest measures long. '78,Jat. 1*38, alt. *5. JTab. Gulf of California, Mus. Cuming. Mazatlan ; extremely rare adult, rare jun., nestling in crevices of Chamse, Spondyli, Ostrese andPerna; L pool Col. ? Guaymas, Lieut. G-reen- Tablet 420 contains 3 minute valves and 2 pairs jun. 421, a young specimen in situ on the back of a Perna, on which is the lower valve of Discina Cumingii, attached. 422, an adult specimen. GENUS VENEEICAEDIA, Lam. 119. ? VENERICARDIA , sp. ind. Tablet 423 contains a minute valve, whose characters are all those of Cardium except the hinge. This however presents a triangular cardinal tooth, with pits for the 2 opposite ones, and an indistinct, closely approximate anterior lateral. There is no trace of posterior tooth. The outside is ribbed almost exactly as in Cardium graniferum ; but instead of the inter- Nov. 1855. * MAZATLAN BIVALVES stices being pitted, the whole shell is decussated by very fine rather distant concentric ridges, passing over and between the ribs. The large ventral ribs are hollowed in the interior of the shell. Long. '03, lat. '04, alt. '02. Hab. Mazatlan ; one valve in Spondylus washings ; L'pool Col. GENUS ? TRAPEZIUM, Megerle. Megerle von Muhlfeld, Untwurf&c. p. 68, 1811 -.Phil. Hand. Condi, p. 350. Libitina, ScJmm. 1817. Cypricardia, Lam. An. s. Vert. 1819. 120. ? TRAPEZIUM , sp. ind. Tablet 424 contains a puzzling little shell, too young to identify even generically. It is shaped like the adult, not the young of Cardita, but entirely without radiating ribs. Shell transparent, subrhombic, irregular, anteriorly truncate, umbos projecting, lateral ; valves smooth, with a few regular distant concentric epidermal ridges ; inside with a very stout projecting cardinal tooth, fitting between two small ones in the opposite valve, and a posterior lateral tooth in each. Ligament external : no trace of pallial sinus. Long. '02, lat. '04, alt. '03. Hab. Mazatlan ; 1 pair, in shell washings ; L'pool Col* FAMILY CHAMHLE. This aberrant family is placed by Lam. and Woodw. between Unio and Tridacna ; by D'Orb. between Spondylus and Ostrea ; by Gray between Saxieava and Cardita - T by PhiL between Cardium and Lucina. In its adherent mode of life and irregular growth it resembles Ostrea ; while its two large adductors and its siphons remove it far away. Both animal and shell have relations with Isocardia (Glossidse, Grray) which was, not so unnaturally as might appear at first sight, associated with it by Linnseus. * Of the two species of GouHia in the Cumingian Collection, G. cerina, C* S. Ad. is congeneric with the so called ' Circe ' minima, not with the G. Pacifica of the same author. Congeneric with the latter species and with G. varians are Crassatella Martinicensis, D'Orb., intermediate in form between the two Mazat- lan species, and Crassatella Guadaloupensis, D'Orb. the exact analogue of G. Pacifica. For which group the generic name is to be retained, those who hav& seen the diagnosis must decide. MAZATLAN BIVALVES 87 GENUS CHAMA, (Pliny J Linn. 121. CHAMA FEONDOSA, Brod. var. MEXICANA. Chama frondosa, var. 1. Brod. Proc. Zool. Soc. 1834, p. 149. Zool Soc. Trans, vol. i. p. 302, pi. 38, f. 1, 2. Rve. Condi. Ic. pi. 1, f. 1 b.B. M. Cat. D'Orb. Moll. p. 87. no. 773. Compare Chama echinata, Brod. in Zool. Beech. Voy. p. 150, pi. 43. f. 9. (? = C. echinata, pars, Brod. Proc. Zool. Soc. 1834, p. 150: Trans. Zool. Soc. 1835, p. 305, pi. 39, f. 57. Rve. Conch. Ic. pi. 7, f. 35, jun. C. B. Ad. Pan. Shells. p. 254, no. 407.) The Mazatlan Chamse were sent in tolerable numbers, and yet so commonly were their surfaces abraded that it is difficult to discriminate the specific characters. The bulk of them are certainly C. frondosa, var. b, of Brod. and Rve., but were con- sidered a distinct species by Messrs. Cuming and Hanley. The typical C. frondosa comes as far north as S. W. Mexico (P. P. C.) but was not found among the Mazatlan shells. I have not ventured however to describe it as a distinct species, till more is known of its power of local variation. Shell when extremely young (as shewn by examining the umbos of the smallest valves found, under a half-inch achrom.) somewhat Venus-shaped, with concentric ridges, and a very finely shagreened surface, occasionally passing into very fine radiating stria? : interior as in adult. Many of the shells do not display this structure, but pass at once to the next stage, generally with vaulted spines, sometimes with irregular laminae. The inner margin at an early state is not crenulated : colour white, gradually developing a rich pink. In its adolescent condition, the interior is of a rich plum purple, irregularly diffused, more or less stained with orange, especially at the teeth. The margin during this period often displays a most minute set of crenulations, within the line of meeting of the valves. All the specimens found in this state had lost their external characters. When properly adult, it is generally cover- ed with very irregular concentric layers rising into lamellae, rarely into spines, with a tendency to broader foliation in a pos- terior radiating area, ill defined. The interior crenations become then almost extinct. Colour outside brownish red, within white, more or less stained with the same. Shell attached sideways, generally by about a third of its surface, with very large adductors, and hinge teeth which are more or less ser- rated ; white, bordered with purplish brown. The ligament MAZATLAN BIVALVES is strong, curling round the umbos, like Isocardia, and becom- ing semi-internal beyond the hinge teeth. All the specimens are dextral. The laminse are generally finely striated outside. These shells, like those of Spondylus, offered a safe retreat for boring and nestling bivalves and numerous minute Gas- teropods. The smallest valve measures '02 across. That with the largest animal, (shell somewhat thin,) long. 4*5, lat. 4*25. alt. 3 '4. The heaviest shell measures externally (though part has been removed) long. 5*7, lat. 5', alt. 5' ; internally (from ligament to margin) long. 2*6, lat. 2 '8, alt. 2' 2. This, with another smaller specimen attached, weighs 51b. ; and displays a very large and persistent spiral ligamental groove. Hal). Gulf of Tehuantepec, Mexico ; dredged up from sandy mud attached to Aviculse, 10 fm. ; Mus. Cuming. Mazatlan ; not common ; L'pool fy Havre Coll* Tablet 425 contains 3 valves, extremely young, exhibiting the shagreened surface at the umbos. 426, 2 do. umbos finely striated. 427, 1 do. umbo spiral, as in young Calyptrseadse. 428, 1 do. concentric foliations developed. 429, 8 valves, a stage older, spiny processes developed, valves inside variously coloured, and surface rugose. 430, 1 pair and 3 valves, a stage older, colour highly developed. Tablet 431 contains 1 pair young. 432, a specimen with the spiral umbos so enormously developed, as to approach the fos- sil form Diceras. The umbo of the attached valve makes two loosely spiral whirls, the ligament running up the suture ; in length it nearly equals the breadth of the shell, but being filled up with solid matter, would not display itself in the internal cast. Tablet 433 contains a pair, young, purple and orange, (closely resembling the C. echinata, "very old," figured in Beechey's Voyage.) Margin very finely, and teeth strongly crenate. Outside, with Vermetida3, Lithophagi, &c. 434, 2 valves at- tached to each other, pierced by Lithophagi, &c^ The outer layer has become eroded, except where the Lithophagi have bored. Tablet 435 contains a diseased specimen, purple, attacked by Lithophagi, even to the very centre of the teeth. Tablet 436 contains a finely grown adult specimen, attached to Pinna, with Vermetidse &c. 437, the sp. with the largest animal. 438, the group with the largest shells. * A specimen received from Dr. Gould of this species (without reference) is probably the "C. Pacifica" of his list, "Guaymas, Lieut. Green." It may however be the C. Buddiana, C. JB. Ad. : v. infra. MAZATLAN BIVALVES 89 J_ 121, b. CHAMA ? FBONDOSA : var. FOBNICATA. C. ?f rondos a, I. costis numerosis irregularibus radiantibus, squamis fornicatis crebris indutis ; hue et illucf rondos a ; intus alba, ad marginem rubro-purpurea ; margine crenulato ; den- tibus ad apicem valde serratis ; epidermide cinered ; per totum latus affixd. Compare C. Buddiana, C. B. Ad. Pan. Shells, p. 253, no. 405 ; Panama, rare ; Guaymas, Lieut. Green. A few specimens differed from the rest of the Mazatlan Chamae in having the surface (especially anteriorly) covered with radiating costae, rising into scales which are often semi- tubular. The colour never displays the rich purjple and orange of C. frond. Mexicana, being white bordered with puce. The attachment is more completely lateral ; margins more strongly crenate ; edge of hinge tooth sharply serrate. Shell covered with an ashy epidermis; sometimes olivaceous, not noticed even in young specimens of C. frond. Mexicana. These charac- ters might be sufficient to mark out a species, if constant : but as I find many of the adult specimens that cannot be referred with certainty to either form ; and as each of the characters (except that of the epidermis) is in both forms subject to vari- ation, their claim cann6*t be regarded as established. The shell seems to have relations both with C. Broderipii and C. Buddiana : on the other hand it sometimes displays posteriorly- more of the characters of C. frondosa proper than does the ordinary form. The, valves unite so closely that a specimen (attached to Byssoarca) on being opened, two years after being brought to this country, was found full of the soft animal mat- ter, of course in a state of the most fetid decomposition. In the young state it is not to be distinguished from C. frond. Mexicana, and scarcely from C. spinoga. It is also of the same size and habit of growth. Hob. Mazatlan ; very rare ; L'pool Col. Tablet 439 contains 2 pairs and a valve, very young. 440, a pair young. 441 a pair well formed, adhering to the inside of a very large valve. The latter is incrusted with Sponge, Ver- metidae, &c., and nestled beneath the umbo two specimens of Byssoarca gradata have found a home. 442, a sp. attached to living Byssoarca jpacifica (v. supra). 443, a large specimen, containing in the upper valve Petricola robusta in situ ; in the lower, which had been attached to ? rock by a large surface, MAZATLAN BIVALVES a Gastrochsena truncata in its burrow, and a Petricola robusta which, after penetrating to the Frock, has flattened itself rather than bore into the harder substance. 122. CHAMA SPINOSA, Brod. Proc. ZooL Soc. 1834, p. 150. Eve. Conch. Icon, in loc. Three small valves and one pair appear to belong to this species. The valves differ from the young of C. frond, fornicata, in having the entire surface crowded with semi-tubular spines ; and in the character of the margin, which is smooth and rounded within, outside with crowded scales one on another, like the base of Hipponyx tessellata. The types and the pair do not display this structure, which appears very characteristic. Hinge teeth comparatively small ; muscular scars not very large ; colour white, with slight rosy tint at the umbos which are scarcely spiral. Long. 1*1, lat. I'l, alt. '08. Hob. Lord Hood's Island, Cuming- ? Mazatlan ; extremely rare ; L'pool Col. Tablet 444 contains a valve. The pair will be seen, attached to Ostrea, with Discina, on tablet 20. 123. CHAMA PEXOGYRA, Conr. One broken pair attached to a pebble, and a valve on Spondy- lus calcifer in the Liverpool Museum, differ from the rest of the Mazatlan Chamse in the following particulars. Shell sinis- tral ; ventrally produced ; surface roughened and laminated, not spinous ; margin smooth, rounded off, slightly crenate outside ; teeth long, small, colour reddish brown, without purple. They may belong to Ch. Panamensis, or even to Ch. corrugata,'but seem best to accord with this species. Long. 1 * 5, lat. 1'17, alt. 1'15. Hab Sta. Barbara, San Diego, &c. Nuttall Mazatlan ; ex- tremely rare ; L'pool Col. Tablet 445 contains the specimen on pebble. FAMILY CAEDIAD^E. GENUS CAHDIUM, Linn. Only two species of this abundant genus were sent in any quantity ; the shell washings however proved that many more must exist in the neighbourhood ; 5 species being found suf- MAZATLAN BIVALVES 91 ficiently perfect to describe with tolerable accuracy ; and fragments of 5 others presenting characters by which they may be hereafter distinguished. JL 124. CAEDITTM (L^EVICABDIUM) ELATUM, Sow. Pro. Zool. Soc. 1833, p. 84. Rve. Condi. Ic. sp. 41, pi. 8, f. '41. This most magnificent cockle is known at once by its large size, smooth surface and yellow colour. It has however very faint, nearly obsolete ribs, covering the body of the shell ; but even these are not to be seen on a large, distinctly marked, posterior and a smaller anterior portion. About the umbos there are no longitudinal ribs, but very faint concentric ridges of growth. The shell has a decided posterior gape : edges crenated within, except at the smooth parts : posterior lateral tooth in one valve marginal. Epidermis thin, crossed with numerous very fine concentric ridges. If I. have rightly affiliated the young shells, (but there is nothing intermediate between '11 and 2 '63,) in its early state it is somewhat spotted, and much more transverse. The little shells suit better the description of C. Elenense. The teeth vary greatly in size, and the shells in thickness. Some of the young shells under a low power, and all under a high one, dis- play a pustulose surface, which ?may be traced near the umbos of the smallest distinct specimen of C. elatum. The smallest minute valve is '03 across; the largest specimen measures long. 5 '85, lot. 4 '58, alt. 3 '92. Hah. Gruaymas, in sandy mud at low water, Mus. Cuming. San Diego, Lieut. Green. Mazatlan ; not uncommon ; IS pool <$f Havre Col. Tablet 446 contains the smallest and largest distinct speci- mens. 447, 3 perfect and 2 imperfect valves of C. ? elatum, jun. 4~ 125. CARDITJM PROCEEUM, Sow. Proc. Zool. Soc. 1833, p. 83. Mull. Syn. Test. Viv. p. 216. Sow. Conch. HI. no. 61, pi. 50, f. 23. Rve. Conch. Syst. pi. 77, f. 23 : Conch. Ic. pi. 10, f. 51. Hani Descr. Cat. p. 140. Menke, Zeit.f. Hal. 1847, p. 188, no. 51. .B. M. Cat. D'Orb. Moll. p. 74, no. 659. C. _#. Ad. Pan. Shells, p. 267, no. 433. This shell deserves favourable regard not only on account of the beauty of its form, but also because it has been quoted in 92 MAZATLAN BIVALVES no fewer than eleven books without a synonym ! The young shell however has not been so well treated, being, according to Jay and Reeve, the C. laticotitatum of Sotv. It certainly suits exactly the description and measurements given in Proc. Zool. Soc. 1833, p. 85. Mr. Cuming however states that C. laticostatum is distinct and is the larger of the two ! The young C. procerum moreover is not to be distinguished from the figure of the young C. Panamense in Zool. Seech. Voy. pi. 42, f. 7, which is described by Sow. Proc. Zool. Soc. 1833, p. 85, as only 1*5 in. long. The specimens in the Cumingian Collection however are extremely large. The Mazatlan shells are manifestly of one species. It begins life nearly orbicular. A young shell, *5 in. long, displays 7 close posterior ribs, sharply serrated at the margin, and with rows of tubercles on their summits. The 10 ventral ribs are then sub triangular, rather sharp, minutely dotted at the top, and with the sides and very narrow interstitial spaces finely decussated by con- centric ridges which travel up and down over them. The six anterior ribs are very much flattened, and faintly decus- sated by the concentric lines. Gradually both tubercles and concentric ridges disappear, at an earlier or later period ; the ribs then become flattened, and at last on the anterior part nearly pass away. The shell assumes a longer or broader form, with every gradation between. The number of ribs varies from 21 25, and does not depend on the shape. The colour is whitish, variously spotted with reddish brown ; inside near the posterior margin, (which is very ringent,) of a rich brown- ish purple. The ends of the ribs project beyond the margin of the shell at the posterior ventral part, and beautifully inter- lock. The side teeth are in a very slight curve from the car- dinal. Epidermis thin, with very closely concentric ridges. A broad specimen measures long. 2*5, lot. 2*2, alt. 2*04. The largest,, 3'07, 2'5, 2'22. Hob. Real Llejos, in coarse sand 4-6 fm. Cuming. Payta, TfOrbigny. Panama, rare, C. B. Adams. S. W. Mexico, P. P. C. Mazatlan, Melchers. Mazatlan : common ; I/pool fy Havre Coll. Tablet 448 contains a minute imperfect valve. 449, broad variety, 5 pairs and a valve, young. 450, do. 3 sp. adult. 451, 4 sp. young, elongated form. 452, 3 do. adult. 453, a curiously deformed valve. MAZATLAN BIVALVES 93 126. CARDIUM ? SENTICOSUM, Sow. Proc. ZooL Soc. 1833, p. 84,Miill. 8yn. Test. Vlv. p. 218. Sow. Conch. III. no. 43, pi. 47, f. IQRve. Conch. Syst. pi. 74, f. 10: Conch. Ic. Ind. Card. & Errata. Hani. Descr. Cat. p. 137. R M. Cat. D'Orb. Moll. p. 74, no. 658. C. S. Ad, Pan. Shells, p. 268, no. 434. = Cardium rastrum, Rve. Conch. Ic. pi. 16, f. 82.* ? = Cardium muricatum, MenJce in Zeit. f. Mai. 1847, p. 188, no. 50. Tablet 454 contains a nearly perfect minute valve and 6 frag- ments of larger shells, which probably belong to this species. The ribs are extremely close, about 40, and bearing traces of grains which are strongest on the anterior side. The smallest fragment has a fine line running down the interstices, which is probably an accidental variety, as I have a specimen of C. echinatum displaying the same structure. C. muricatum is the West Indian analogue. Sab. St. Elena, in sandy mud, 6-12 fm. Cnming. Ecuador ; St. Elena, Tf Orbigny. Taboga ; very rare ; C. J3. Adams. ? Mazatlan ; extremely rare, in shell washings ; L'pool Col. 127. CARDIUM: - sp. ind. (a.) C. t. ?jun. minima, orbiculari, costis circiter xl. approxima- tis, hand extantibus, graniferis ; s up e rfi cie tot a minutis- sime quasi arenatd, dentibus lateralibus hand magnis. Two valves and a fragment only were found of this shell, differing from C. punctulatum, JBrod. fy Sow., ZooL Journ. vol. iv. p. 366, in the characters above named. The entire surface appears as though dusted over with grains of sand. It appears to be a young shell : if the adult, when found, have the same characters, it may take the name of C. arenatum. Long. '08, lot. '08, alt. '06. Hob. Mazatlan ; from Spondylus washings ; extremely rare ; L'pool Col. Tablet 455 contains a nearly perfect valve. * "Mr. Reeve's reference to P. Z. S. 1841 for Sowerby's description is evidently a misprint for 1833 ; and the reference to the same work, 1845, for C. rastrum seems erroneous. Mr. Hanley's reference to Reeve Conch. Syst. pi. 84 is also a misprint for 74." C. B. Adams, loc. cit. 94 MAZATLAN BIVALVES 128. CAEDIUM , sp. ind. (I.) Tablet 456 contains a fragment; of a shell of moderate size, which may possibly be C. triangulatum, Sow. (St. Elena and Isle Plata, Owning.) It has very broad flat ribs, with 2 rows of tubercles on each. These communicate with decussating lines in the interstices. Hob. Mazatlan ; from shell washings ; Lpool Col. 129. CAEDIUM sp. ind. (c.) Tablet 457 contains a fragment of a moderate sized Cardium, having relationship with C. pseudofossile, Rve. (Hearing's Sir.) It is of a dead white, with very close, stout, numerous, rounded ribs, barely nodulous. Hab. Mazatlan ; from shell washings ; L'pool Col. 130. CAEDIUM sp. ind. (d.) Tablet 458 contains a fragment of a thin white shell with perfectly triangular, rather distant ribs, with flat sides. The interstices are smooth, bounded by clearly marked lines. Hab. Mazatlan : from shell washings ; L'pool. Col. 131. CAEDIUM , sp. ind. (e.) Tablet 459 contains 2 fragments, something like the last, but coloured, and with the ribs rounded and slightly nodulous. Sab. Mazatlan ; from shell washings ; L'pool Col. 132. CAEDIUM sp. ind. (f.) Tablet 460 contains 2 minute fragments, with very narrow smooth rounded ribs, very far apart. Interstices broad, smooth, bounded by distinct lines. Hal. Mazatlan ; from shell washings ; L'pool Col. 133. CAEDIUM ALABASTEUM, n. s, C. t. parvd, alba, nitidd, subdiapkand, subcequilaterali, elongatd ; costis circiter xviii., quorum quatuor v entrales mag nee, distantes, costellis utraque subtrigonu- lalis apicem versus granulatis ; interstitiis minutissime decus* MAZATLAN BIVALVES 95 satis ; parte anteriore punctis ovalibus impressis decussatd ; dentibus lateralibus approximatis. This charming little creature has a general resemblance to a minute C. costatum ; but the large ventral costse are rather rounded, with a little one on each side making them appear somewhat trigonal. The anterior portion is strongly indented with oval pits. The appearances it presents under the micros- cope vary greatly according to the direction of the light. The young shells have fewer ribs near the hinge, where the teeth are not fully developed ; are rather less sequilateral ; and are granulose on the ribs. Long. '12, lat. '11, alt. '08. Hob. Mazatlan ; in Chama and Spondylus washings ; ex- tremely rare. Tablet 461 contains 2 valves, the largest and the smallest. 134. CARDIUM O-RANIFEEUM, Brod. fy Sow. ZooL Journ. vol. iv. p. 367. Sow. Conch. HI. no. 38, pi. 49, f. 17. Rve. Conch. Syst. pi. 76, f. 17 : Conch. Ic. pi. 8, 43. Hani. Descr. Cat. p. 137. C. B. Ad. Pan. Shells, p. 266, no. 430. .S. M. Cat. D'Orb. Moll. p. 73, no. 652. The smallest valve found, which only measures '03 across, scarcely shews a trace of teeth. The young shells are nearly rectangular at the posterior end ; when older, they are obtuse angled. The interstices between the ribs are decussated by a series of rectangular impressed pits laid transversely. The largest specimen found measures only long. '12, lat. '12, alt. *06. Hob. Dug from a depth of about 6 inches in the mud of the Estaro de Mazatlan ; Lieut. Belcher. Gulf of Mcoyia and Xipixapi ; Cuming, _D' Orbigny. Panama, extremely rare, C. B. Adams. Mazatlan ; a very few young valves and frag- ments in the washings of Chamse and Spondyli ; L'pool Col. Tablet 462 contains the largest (imperfect) valve, and two small ones. 135. ?CAEDIUM , sp. ind. (g.) ? C. t. juniore suborbiculari, albidd, valde incequilaterali ; margine dorsali postice recto, antice concavo ; costis- circiter xviii. validis, rotundatis, approximatis, tuberculis latis armatis ; dentibus elongatis, lateralibus distantibus. 96 MAZATLAN BIVALVES A puzzling little shell, of which were found only one minute valve and a larger fragment. R r markable for the very stout ribs, well armed with coarse tubercles, and for the Lucina-like shape of the dorsal margin. It has about 10 ventral ribs, but the species probably has more when adult. If then of the same shape, it may take the name of C. lucinoides. Long. '04, lat. "04, alt. '03. Hob. Mazatlan ; extremely rare ; in shell washings ; L'pool Col. Tablet 463 contains the valve. FAMILY LUCINID^E. GENUS LUCHSTA, Brug. This genus, so abundant in the Atlantic, and especially in the West Indies, appears very rare on the Pacific coast of America. C. B. Adams records only one species from Panama, and this does not belong to the genus ; D'Orbigny none from the West coast of S. America. Reeve describes 3 species (fibula, eburnea, and calculus) discovered by Mr. Cuming, be- sides L. punctata and muricata, previously known ; and L. annulata from ? California. Dr. Gould has another, from Acapulco. Only one small species was at all common in the Mazatlan collection ; though there is evidence of the existence of a tolerable number of others. Some of the Lucinse are not at all constant in their characters ; the same species sometimes displaying, or not, radiating and concentric ribs, and having its margins smooth or crenated. Not a few of the species appear to have a very wide distribution ; L. occidentalis, Rve. (olim pecten) being quoted from the West Indies and Ld. Hood's Island, and L. borealis from the British Seas and the Philippines. Many of the Mazatlan species were found en- tangled in the byssal mass of the large Modiolse. * 136. LUCINA (CODAZIA) TIGEKINA, Lin. Venus tigerina, Linn. Syst. Nat. p. 1133-4. Bom Mus. p. 70. Ckemn. vii. p. 6, t. 37, f. 390-1. Schroeter Mnl. iii. p. 136. Mont. Test. Br. p. 119, t. 4, f. 1 Dorset Cat. p. 35, t. 1. f. U.DiUw. Cat. vol. i. p. 191, no. 76 : Sfc. Cytherea tigerina, Lam. An. s. Vert. ed. 2, vol. 6, p. 318. Turt. Dyth. Br. p. 164, pi. 10, f. 12. Flem. Br. An. p. 445. MAZATLAN BIVALVES 97 Lueina tigerina, Desk. Enc. Melh. vers. t. 2, p. 384, no. 37. Sow. Gen. Luc. Desk, in Lam. loc. cit. p. 318, (2). Forbes $ Hani. Sr. Moll. vol. ii. p. G4. B. M. Cat. Cuba Moll p. 41, no. 499. This abundant W. Indian shell will not be received by many as belonging to the Pacific fauna. I can only say that I found the specimen, papered and numbered in the Dqsinia box, per- fectly fresh, and bearing every mark of having been taken alive. As further evidence of its lingering existence in these seas, I record finding a fresh valve among a collection from the S. W. Mexican coast. The shells are both exactly like the normal W. Indian type, and differ essentially from its Panama analogue, L. punctata, Linn. Long. 1*48, lat. 1*6, alt. '58. Hab. West Indies, passim. (Jamaica, Lister. Barbadoes, P. P. C. St. Domingo, D'Avila. Cuba, Sagra.) Amboyna, Humphius. Nicobar Is., Chemnitz. [Britain, Montague, &c. ? imported.] S. W. Mexico, 1 fresh valve, P. P. C. Mazatlaii ; 1 fresh specimen ; L'pool Col. Tablet 464 contains the specimen. 137. LUCINA ?? PUNCTATA, Linn. Venus punctata, Linn. Sysf. Nat. p. 1134. CJiemn. Conch. Cab. vii. p. 15, pi. 37, f. 397-8. Cytherea punctata, Lam. An. s. Vert. vol. vi. p. 319, no. 54. Lucina punctata, Desk. Diet. Class, d'hist. nat. t. 9. Sow. Gen. Luc. f. L Eve. Conch. Ic. pi. 1, f. 2. Tablet 465 contains two minuts valves, '03 across, which are evidently the young of a somewhat large species, perhaps this. One of them has close radiating ribs from the commencement ; the other is smooth, with strife of growth ; till, near the margin, after a sharp concentric ridge, it suddenly betakes itself to making longitudinal ribs. The teeth somewhat resemble the young of Dione, with the extreme ones very large in proportion, Hab. "L'Ocean des G-randes Indes," Lamarck. Panama, on the sands at low water, Cuming. ?? Mazatlan ; jun. extreme- ly rare, in shell washings ; Lpool Col. 138. LUCINA PANNULATA, Reeve. Reeve, Conch. Ic. pi. 4, f. 17. Tablet 466 contains a fragment with rounded concentric ribs, and very fine concentric stria) traveling over both ribs and Nov. 1855. Jc 98 MAZATLAN BIVALVES interstices, which may belong to this species. Hab. ? Mazatlan : in shell washings ; IS pool Col. 139. LUCINA PMURICATA, Chemn. Tellina muricata, Chemn. Conch. Cab. xi. pi. 199, f. 1945-6, Lucina rmiricata, Hve. Conch. Ic. pi. 8, f. 46. Tablet 467 contains a fragment, with extremely fine, close,. radiating ribs, rising in concentric lines into sharp scales. Sab. PMazatlau ; in shell washings ; L'pool CoL 140. LUCINA EXCAVATA, n. s.. L. t. alba, tenui, complanatd; suborbiculari; striis concentricis exillimis ; postice angulata, umbonibus incurvatis ; lunuld parvd, alte excavatd; dent. card, et lot. haud magnis ; impressionibus muscularibus postica ovali, anticd valde elonga- td ; margine integro. Distinguished by the very small, most deeply cut lunule, bounded on one side by the cardinal, on the other by the anterior lateral tooth. A larger lunular portion is marked out by a line, and the posterior margin is slightly bi-angulated. Smallest valve '03 across. Largest, long. '38, lat. '41, alt. '12. Hab. Mazatlan ; 2 valves and fragments among shell wash- ings ; L'pool Col. Tablet 468 contains the two valves, and a fragment to shew the external surface. 141. LUCINA , sp. ind. Tablet 469 contains a fragment,, smooth outside, with the umbo slightly projecting ; inside with a stout round cardinal tooth, and deeply impressed internal ligament pit, I have a very similar species from Port Jackson. Hab. Mazatlan : in shell washings ; IS pool Col. 142. LUCINA PECTINATA, n. s. L. t. albidd, suborbiculari, planatd, marginibus rotundatis ; costis radiantibus appressis, hue et illuc bifidis,juniore circiter x- adulta circiter xxx. ; postice non divaricatis ; lineis frequentis- simis concentricis a costis undatis ; lunuld parvd ; dent, card* et lat. haud magnis ; ligamento subintemo ; impressionibus muscularibus postica subrotundatd, antica valde elongatd. MAZATLAN BIVALVES 99 Differs from L. cancellaris in being much larger and flatter, with the teeth and lunule smaller in proportion. There is no posterior angle or flattening. The radiating ribs divide as in L. cancellaris, but the concentric ridges, instead of being sharp and standing so as to leave deep pits between, are very close and fine, running up and down across the ribs and inter- stices. It seems closely allied to L. fibula (St. Elena and Philippines), and to L. costata, D'Orbigny, (Brazils.) Long. '44, lot. '49, alt. '16. Hab. Mazatlan ; one fresh valve and fragment, entangled in the byssus of Modiolse ; Lpool Col. Tablet 470 contains the valve. 143. LUCINA CANCELLARIS, Phil. Zeit.f. Mai. 1846, p. 21, no. 7. Shell, when extremely young, smooth at the umbo, then with stoi.it concentric ridges, then with 8 or 10 very strong radiating rounded ribs crossing them. These branch out into other narrower ones, till there are about 26, strongly cancel- lated, and leaving deep pits between. "The form closely resembles L. commutata, Phil., which is the real T. divaricata of Linnaeus. With L. pecten, squamosa and reticulata (Poli, not Lam.) it must not be confounded ; its strong rotundity, almost equilateral form, and the character of the sculpture at once distinguish them." (Phil. loc. cit.) Lunule small, deep : posterior ligamental portion flattened, separated by an indis- tinct keel. Interior margin deeply crenated ; muscular scars (anterior elongated, irregular) rather distant from margin ; lateral and cardinal teeth strong. The smallest specimen is '03 across. The largest, long. '15, lot. '14, alt. '09. Sab. Mazatlan, Philippi. Do. : extremely rare ; L'pool Col. Tablet 471 contains the youngest valve and the largest pair. -/-" 144. LUCINA MAZATLANICA, n. s. L. t. parvd, albd, suborbiculari, umbonibus antice incurvatis, lunuld longd, tnargine posticd obscure biangulato ; primum liris concentricis, acutis, plus minusve distantibus ; postea radiis quoque rotundatis, creberrimis, ad marginem decurrentibus ; liris ad angulam posticam quibusdam obsoletis, reliquis extan- tibus ; area posticd subplanatd ; dentibus card, parvis, lat. sub- distantibus ; ligamento curto, subexterno ; impression^ us mus- cularibus haud elongalis ; margine (haud semper) crenato. 100 MAZATLAN BIVALVES Though 200 valves were found, many of them fresh from the banquets of carnivorous Gasteropoda, there was only one pair. When young, nothing is seen but the concentric ridges ; the shell is then elongated anteriorly, and scarcely to be distin- guished from the young of L. prolongata ; afterwards it assumes a regular, rounded form, with the posterior part flattened, and bearing fewer but more elevated ribs. The radiating ribs first appear at different ages, and are very close and little raised. The margin is often not crenated in the young shell. The smallest valve is only '03 across ; an unusually large one measures long. '15, lat. '16, alt. '09. Sab. Mazatlan ; in shell washings, between the ribs of Cardia, in crevices of Chamae and Spondyli, &c., not uncommon ; If pool Col. Tablet 472 contains the pair, and 14 valves of different ages. Tablet 473 contains 3 valves, which may be an elongated variety of this species, or the young of L. prolongata. 145. LUCINA PBOLONGATA, n. ,?. L. t. parvd, Jlavidd, solida ; antice, maxime prolonga- t a : marginibus rotundatis, lunulci longd, umbonibus antice incurvatis ; liras concentricas rotundatas plus minusve mon- strante ; intus dent, crassioribus, lat. subapproximatis ; impres- sionibus muscularibus regularibus, subovalibus ; margine interno seu planato sew cremdato : ligament parvo, externo. Shell somewhat resembling L. calculus, Rve. (Conch. Ic. pi. 11, f. 68, taken in coarse sand, 10-13 fm., G-ulf of Nicoyia, CumingJ which however is described as smooth, polished, shining white. This is of a yellowish cast ; and though the rounded ridges are often nearly obsolete, yet it is never polished. On one speci- men were 3 deeply cut concentric sulci. The young shell has its ribs sharper, when it resembles L. Mazatlanica. The pos- terior part is rounded off. Inside there is a glossy deposit over the mantle part, the margin being very finely rugose. The muscular scars in this species and the last are much more equal than in the typical forms. The smallest valve is '04 across ; the largest measures long. '16, lat. '13, alt. '08. Hob. Mazatlan ; from the crevices of Chamse and Spondyli, very rare ; L'pool Col. Tablet 474 contains a large and a small pair, and 5 valves differing in age and markings. One, having been bored by a MAZATLAN BIVALVES 101 Gasteropod and then deserted, has made a coating over the hole inside. 146. PLuciNA , sp. ind. Tablet 475 contains a fragment of a pinkish shell with very smooth angular ribs. Hah. Mazatlan ; in shell washings ; L'pool Col. 147. LUCINA PEBURNEA, Reeve. Conch. Icon. Lucina, sp. 49, pi. 8, f. 49. Tablet 476 contains a young valve of exquisite beauty which may belong to this species, unless indeed it be a Strigilla lenti- cula. It is of glossy white, and so transparent as to shew the muscular impressions outside, and the external markings within. Suborbicular, with umbo very projecting between two concave margins and nearly central. Surface covered with very crowd- ed concentric striae, which at the margin shew a tendency to commence divarication. It is '06 across. Hob. St.. Elena and Panama, in sandy mud, 11 fm. Cuming. ? Mazatlan ; one valve in Spondylus washings ; L'pool Col. 148. LUCINA , sp. ind. Tablet 477 contains a fragment of a thin, globose species, with very numerous sharp concentric ridges ; interstices de- cussated by very fine radiating striae. Hob. Mazatlan ; fragments of two specimens in shell wash- ings ; L'pool Col. GENUS PFIMBEIA, Meg. Fimbria, Megerle v. MilMfeld, 1811, Untwurf&c. p. 52. Corbis, Cuv. 1817, Regne An. vol. iii. p. 147. Idothea, Schum. 1817, Essai. 149. ? FIMBRIA ,jun., sp. ind. Tablet 478 contains one of two tiny valves which seem to belong to this genus, having the teeth of Cardium, with con- 102 MAZATLAN BIVALVES centric ridges slightly decussated. They are evidently young, extremely thin, and shaped like the fossil F. lamellosa. Long. '06, lat. '08, alt. '04. Hob. Mazatlan ; off Spondylus calcifer, 2 sp. ; L'pool Col. GENUS DIPLODONTA, Bronn. Diplodonta, Bronn 1831, Italiens Tertiargeb. p. 9. Mysia, Gray, Proc. Zool. Soc. 1847, p. 195, (non Mysia Leach,) teste Phil, in Handb. der Conch, fy Mai. p. 342. (rlocomene, Leach (a see-undo, manu,) Br. Moll. 313. For a full account of the remarkable peculiarities of the animal of D, rotundata, v. Clark Moll. Test. Mar. Br. p. 82. 150. DIPLODONTA SEMIASPERA, ? Phil. Quoted by Philippi, in Abbild. Conch. Tellina, p. 25, under Tellina pisiformis, Aug. 1846. ? = Lucina orbella ; Gould, Proc. Bost. Soc. N. H. Nov. 1851, vol. iv. p. 90 : Cal. $ Mex. Shells, p. 22, pi. 15, f. 3. ?=Lucina semireticulata, B. M. Cat. I)' Orb. Moll. p. 72, no. 640 -Do. Cuba Moll. p. 41, no. 498. ?=Lucina cselata, Hve. Conch. Ic. pi. 6, f. 27, a, b. A small colony was found in a burrow in Chama, old and young, most tightly wedged. They apparently lived on till they smothered each other, The shape of individuals varies extremely. Some are nearly globular, others (smaller) much flattened. Some are solid, some with a glossy shell like Kellia. In some the ligament was conspicuous outside ; in others entirely hidden. The outside is sometimes nearly smooth ; sometimes with concentric lines of growth, here and there granulose. The ligamental plate is generally more or less turned in ; the teeth rather divergent and strongly bifid. The muscular scars are rather long, especially 'the posterior one, serrated within, and (with the pallial line) near the mar- gin ; but even these characters seem to vary in every specimen. The umbo in the very young shell is subcentral, with the liga- ment entirely external, and the hinge teeth prominent. The smallest specimen measures '04 across ; the largest, long. '41, lat. '42, alt. '28. After a very careful comparison of the types of L. cselata, L. orbella and D. semiaspera, I am unable to detect differences between them which do not exist between specimens of the MAZATLAN BIVALVE8 103 latter. L. caelata is larger, with tlie rugose markings more coarsely grained ; ligament concealed. L. orbella is of the same size and shape, but rubbed smooth, and with the ligament prominent. D. undata is closely related, but differs in having an anterior lateral tooth in each valve, as well as in outline. Hob. According to Philippi, loc. cit., this species and Tellina pisiformis are found both at Mazatlan and in the W. Indies. St. Thomas', Merle. Mazatlan ; very rare, nestling in bur- rows ; L'pool Col. (D. orbella) San Diego, Lieut. Green. Sta. Barbara, Col. Jewett. (D. semireticulata) Cuba, Sagra: Brazils ; Bio de Janeiro ; Patagonia ; D' Orbigny. Tablet 479 contains 4 pairs and 2 valves, young and flatten- ed. 480, 2 pairs adult. ^|. 150. (b .) DlPLODONTA ? SEMIASPERA, 'Car. DISCREPANS. D. ? semiaspera t. tenui, leviori, impressione postica sub - rotundatd; dentibus elongatis, ligamento omnino externd. Tablet 481 contains a solitary specimen, which, had the other shells been at all constant in their characters, would have been considered a distinct species. As it is, it must await the examination of further specimens, especially as L. orbella, Gould, appears intermediate between this and the typical form. Long. '29, lat. '31, alt. '021. Hob. Mazatlan ; 1 sp. in burrow from Chama ; Upool Col. 151. DlPLODONTA OBLIQUA, Phil. Zeit.f. Mai. 1846, p. 20, no. 6. This species is said by Philippi to differ from D. trigonula in being more oblique, with the umbos not so sharp, and the dorsal margin not so straight. The umbo is placed at one third of the entire breadth. Long. "12, lat. *17, alt. *06. Hob. Mazatlan, Philippi. Do. ; one worn valve from the Chama washings ; Lpool Col. Tablet 482 contains the valve. GENUS A group of very nearly allied species, described by Beeve and D'Orbigny as Lucinse, viz. Lucina Candeana, (Cuba,) L. cornea, (coarse sand, 10-13 fm., Gulf of Nicoyia, Cuming,) L, 104 MAZATLAN BIVALVES nitens, (Is. Muerte, 11 fm., sandy mud, Cuming,) L. tellinoides, (do. Cuming : Taboga, not common, C. B. Adams,) and the following, are placed by Woodward under Diplodonta (Man. MoU. pt. 2, p. 298.) They differ essentially in form and habit from the typical species of that remarkable genus, and have relations (except in the hinge teeth) with Cyrenoides : but until the animal has been examined, it would be presumptuous to create a fresh one for their reception. 152. ? DIPLODONTA SEKRICATA, Reeve. Lucina serricata, Conch. Ic. pi. 9, f. 25. Cyrenoida serricata, P. P. C. Cat. Prov. Mr. Reeve tells us that this shell differs from the others essentially in form ; but his descriptions and figures often oblige students to take many things on trust. It has much the appearance of a brackish water shell, having a glossy epidermis eroded near the beaks. The allied species are however strictly marine ; and even these (though very rarely) are pierced by Gasteropods. The shell is extremely thin, Cyrenoides -shaped, but with the teeth of Diplodonta. Muscular scars elongated, rather irregular, The form is generally elongated, but some- times nearly round ; beaks appressed ; ligament subinternal. The largest specimen measures long. '87, lat. '81, alt. '36. A rounded '72, '73, '31. Sab. Mazatlan ; not uncommon ; IS pool Col. Tablet 483 contains a minute pair, broken, measuring '07 across and 2 minute opposite valves, '03 across, from the Spon- dylus washings, which probably belong to this species. If so, they establish its marine station. The youngest valves, by transmitted light, display a fine radiating fibrous structure. Tablet 484 contains 6 specimens, varying in age and shape. FAMILY KELLIAD^E. The little shells, either overlooked in the days of Lam. or included in the heterogeneous genera Erycina and Amphi- desma, are now found to be inhabited by animals greatly dif- fering from each other. The British members, which alone have been carefully studied malacologically, are distributed by Clark (Moll. Test. Mar. Brit. pp. 88 et seq.) under the families Kelliadse, Montacutidse, Turtoniadse, Arcadse & Ana- MAZATLAN BIVALVES 105 tinidse. The genera also are by no means satisfactorily ascer- tained ; the same shell having been described by Forbes and Hanley as Kellia nitida and Lepton convexum ; v. Br. Moll. vol. iv., app. p. 255. As the animals of the Mazatlan species are entirely unknown, a systematic arrangement of them is not attempted ; and they are simply grouped under genera according to the preponderance of characters. GENCJS KELLIA, Turt. Kellia, Twrton Conch. Dyth. Brit. 1822, p. 56. Erycina, Payr. non Lam. (sp.) Chironia (Laperousii) Desk. Rev. Zool. 1839, p. 356. Bornia, sp., Philippi, Enum. Moll. Sic. 1836, p. 13. Tellimya, sp., Brown, III. Conch. Gr. Br. 153. KELLIA SUBORBICTJLARIS, Mont. Mya suborbicularis, Mont. Test. Brit. pp. 39, 564, pi. 26, f. 6. Tellina suborbicularis, Turt. Conch. Diet. p. 179. Kellia suborbicularis, Turt. Dith. Brit. p. 56, pi. 11, f. 5, 6. Alder, Cat. North, fy Durh. Moll. p. 93. Forbes fy Hani. Br. Moll. vol. ii. p. 87, pi. 18, f. 9, 9a, 9b, pi. O, f. ^.Searles Wood, Crag. Moll. (Palgeont, Soc.) Part ii. p. 118, pi. 12, f. 8, a, 1). Clark Moll. Test. Mar. Brit. p. 89, Petricola suborbicularis, Gray, Ann. Phil. 1825. Erycina suborbicularis, Reel. Rev. Zool. 1844. Tellimya suborbicularis, Brown, III. Conch. Gr. Br. ed. 2, p. 106, pi. 42, f. 14, 15. + Tellimya tenuis, Brown, loc. cit. f. 12, 13. ? + Tellimya lactea, Brown, loc. cit. f. 10, 11. (Kellia 1.) B. M. Cat. Br. Moll. pt. 7, p. 83, no. 2Loven, I. M. 44, 310. Erycina Geoffroyii, Payr. Cors. 30, pi. 1, f. 3 5. Amphidesma physoides, Lam. fide Sow..* Bornia inflata, Phil. Moll. Sic. vol. i. p. 14, & vol. ii. p. 11. After often repeated and most careful examinations of many hundred specimens, comparing them with each other and with the very minute description in the Br. Moll, as well as with every Atlantic specimen that has been accessible, I am unable to give any specific characters by which the Mazatlan shells * A. physoides, Lam. Erycina ph. Desh. The description of this shell (An. s. Vert. ed. Desh. vi. 130, no. \Q t ) will fit any similar species. "A. t. orbi- culato-globosa, hyalina, vesiculari. Hab. au port du roi George. Peron." 106 MAZATLAN BIVALVES can be separated from the British , or the aberrant forms from each other. The general aspect of the shells from the two localities is sufficiently distinct ; the Pacific shell being gen- erally thinner and rather flatter ; but the specimens from the Canaries brought by E. M'Andrew, Esq. so remarkably coin- cide with those from Mazatlan that Prof. Forbes was unable to distinguish them. The same changes of form observable in the Atlantic shells obtain in the Pacific. Sometimes it is very broad, with the ventral margin produced and flattened ; sometimes orbicular, with all the edges well rounded. Sometimes (like its fresh- water neighbour Cyclas cornea) it is considerably flattened, sometimes very much swollen. The umbos vary in the same manner ; sometimes being but slightly prominent, sometimes very tumid and projecting, occasionally capped like Cyclas calyculata. The texture also is by no means constant ; being sometimes hyaline and perfectly transparent, sometimes of a dull ashy colour, sometimes opaque white. One valve, agree- ing in other respects, displays a large honeycomb pattern, the cells being transparent on an opaque ground. Most unexpect- edly of all, differences are found in the hinge. The small cardinal teeth are sometimes distinct and conical, sometimes they pass off gradually into the laterals. These are sometimes long and slender, sometimes short, strong, slightly truncate. Some- times the ligament pit is concealed ; sometimes very conspicu- ous while the adjacent teeth are small. Often one or both of the cardinal teeth are absent (probably through accident,) and the laterals are scarcely perceptible ; at other times they are unduly prominent. The aspect of the shell is generally slightly iridescent, either smooth or with extremely faint striae of growth, with a very thin rather glossy epidermis. Almost all the Mazatlan specimens were found nestling (not boring) hi family groups, in holes and crevices of the large Chamse, Spondyli, &c. ; the finest and most characteristic individuals lurking among mixed animal and vegetable debris, in the bur- rows of dead Lithophagi, Petricolse, &c. Most of the specimens found were very young, but displayed their characters accur- ately under the inch or half- inch achromatics. They were frequently found in the small tubes of worms where they could never arrive at maturity. If specimens had been taken from the large hollows of dead bivalves, their favourite haunt in this country, they would probably have been stronger and larger. As the species is known to have existed from the MAZATLAN BIVALVES 107 period of the Coralline Crag, it is natural to suppose that it has now a wide distribution, though its station is such as generally to elude discovery. It would be premature to pronounce absolutely on its specific relations, before the animate have been examined, and other seas more thoroughly searched. The extreme forms are quite sufficiently marked to allow of specific distinction, just as Capt. Brown has described 3 species from the British varieties ; but the known propensities of nestling bivalves, and the presence of intermediate specimens with ever varying characters, do not justify this course. The smallest specimen is '02 across: the largest measures long. '24, lat. *26, alt. ' 15. Hob. British seas, Auct. Mediterranean, Philippi. Cana- ries, M* Andrew. Mazatlan ; not uncommon in crevices of shells, generally young ; L'pool fy Havre Coll. [A species probably identical is from Peru ; ,Col. Cuming. The Chironia Laperousii of Desh., from Monterey, Mr. Hartiveg, is quite distinct.] Fossil : British Coralline Crag ; Searles Wood. Tablet 485 contains 12 pairs, of various sizes. 486, 10 pairs of valves, very young. 487, 10 do, adolescent. 488, 2 sp. which had lived inside a dead Sphaenia fragilis, which had lodged in the hole of a Lithophagus aristatus, which had bored in Murex regius. 489, 4 sp. in situ, in Spondylus calcifer, Patella Mexicana, and Trivia sanguinea. Tablet 490 contains 1 sp. much inflated. Tablet 491 contains a pair of valves, with short truncated teeth : [? var.] 492, 2 pairs and a valve, orbicular. Tablet 493 contains 3 valves, ligamental pit prominent ; [Pvar.] Tablet 494 contains the valve with the honeycomb pattern. GENUS LASEA, Leach. Lasea, Leach ms.B. M. Cat. Br. Moll. pt. vii. p. 81 : Phil. Hand. Conch, p. 345. Lassea, Brown, III. Conch. Gr~ Br. 1827. Lessea, Moll. 1842 Phil. 1845. Bornia sp., Phil. 1836. Cycladina, Cantraine, 1836, Bull. Ac. So. Brux. Poronia, Recluz, 1843, Rev. Zool. p. 166. Kellia pars, Forbes fy Hani. Br. Moll. 1850, vol. ii. p. 85* Autonoe, Leach, (a secunda manuj Br. Moll. 289," 108 MAZATLAN BIVALVES 154 LASEA PRTJBBA, Mont. Cardium rubrum, Mont. Test. Brit. p. 83, pi. 27, f. 4. (non Rve.) Tellina rubra, Twrt. Conch. Diet. p. 168. Kellia rubra, Twrt. DM. Brit. pp. 57, 258, pi. 11, f. 7, 8. Forbes $ Hani. Br. Moll. vol. ii. p. 94, pi. 36, f. 5-7 : (animal) pi. O, f. 3. Clark Moll. Test. Mar. Br. p. 92.--Searles Wood Crag Moll. pt. ii. p. 125, pi. 11, f. 10. Poronia rubra, Red. Rev. Cwv. Zool. 1843, p. 175. Lassea rubra, Leach, ms. Brown Til. Conch. 1827, t. 20, f. 17-19. Les^ea rubra, Brown, op. cit. ed. 2, p. 93, pi. 36, f. 17, 18. Petricola rubra, G-ray Ann. Phil. 1825. Lasea rubra, B. M. Cat. Br. Moll. vii. p. 82. Phil. Hand. Conch, p. 345. Bornia semilunum, Phil. Moll. Sic. vol. i. p. 14, pi. 1, f. 16, & vol. ii, p. 11. Krauss Sudafr. Moll. p. 2. Erycina violacea, Scacchi, Cat. 6. Cy eladina Adansonii, Cantr. Bull. Acad. Brux. Cyclas australis, Lam. An. s. Vert. ed. Desh. vi. 270, (teste Gray.) ? Amphidesma nucleola, Lam. op. cit. vi. 270. Autonoe rubra, Leach, Br. Moll. 288, pi. 12, f. 5, 7. [For other references, v. B. M. Cat. loc. cit]. Whether the little Mazatlan shells (of which only one pair and a few valves were found,) are distinct from the typical European species, must be left for future determination, when its distribution shall have been better ascertained. The teeth are smaller than in most British specimens, but it by no means differs from them so much as do the Mediterranean examples. The late, deeply regretted Prof. E. Forbes considered that they might be identical. He gives the species from the North and South Atlantic. Dunker quotes a similar shell from the G-uinea coast, and Krauss the same from South Africa. I have it from Java, and Singapore (among Chamse). Dr. Gould gives it from Massachusetts, South of Cape Cod. Mr. Cuming found a similar shell in abundance at Valparaiso, on high exposed rocks, seldom washed by the sea, along with a little Littorina, like L. neritea. An extremely similar species is K. miliaris, Desh. from Eagle Bay, Magellan. A species closely resem- bling it in shape but white, and with concentric ridges (which however, being irregular, may be a local variety) is from the Bay of Mexillones, Desert of Atacarnas, Bolivia, adhering to Balani in exposed situations, (Cuming). Lamarck's Cyclas australis is from, the Isle of Timor, with a variety from K. MAZATLAN BIVALVES 109 George's Port, N. Holland, (Peron). From its station in crevices at extreme high water mark, it has probably often escaped detection. It may hereafter be found to be one of the very few ubiquitous species. The Mazatlan specimens were of normal shape, '05 across. Hob. Britain, Mediterranean, &c. : v. supra. ? Mazatlan ; extremely rare, from Chama and Spondylus ; L'pool Col. Tablet 495 contains the pair (broken in opening) and 2 opposite valves, probably belonging to each other. 155. LASEA TEIGONALIS, n. s. L. t. plus minusve trigonali, complanatd. concentrice striatd, umbonibus acutis ; cardine dentibus minimis ; card. 1-2 conicis, rotundatis ; lat. longis, gracilibus, vix monstrantibus ; fossa ligamenti magnd, marginem attingente ; impress, muse, adduct. magnis, subrotundatis. Two specimens of this curious shell were found tightly wedged in the hole of a borer in a Spondylus valve. They are so different that they would be considered specifically distinct but for their position and general habit. One is very trigonal, Nucula-shaped, with a very projecting little conical tooth in one valve fitting between two very small ones in the other. The smaller specimen is of much more regular shape, with the teeth scarcely discernible. Both specimens are flat, concen- trically striated, with a rough epidermis, and are rather pearly within. A minute pair and fragments were also found, the former measuring '03 across. The trigonal specimen measures long. '28, lat. '3, alt. '17. The smallest one '19, '24, '11. Hab. Mazatlan ; nestling in Spondylus, extremely rare ; L'pool Col. Tablet 496 contains the two large pairs and one small valve. 156. ? LASEA OBLONGA, n. s. L. t. obovali, transversd, incequilaterali, tumidiore, a it t ice product'! ; alba, epidermide cinered, horridiore, subpilosd in- dutd ; umbonibus prominentibus ; marginibus undique excurvis ; dent. card, uno, minuto, conico, lat. gracillimis ; fossa liga- menti parvd, appressd. Dec. 1855. 110 MAZATLAN BIVALVES Compare Chironia Laperousii, Desk, in Woodw. Man. Moll. pt. 2. p. 295, pi. 19, f. 11. One fine fresh valve was found of this species, which is not unlike Bornia luticola, Vol. in Rec. Obs. Humb. The latter however appears to have very irregular ridges of growth and stronger teeth. The shell is distinguished by its transverse shape, rough, somewhat pilose epidermis, and minute teeth. It seems to partake of the characters of Lasea and Kellia. Long. '16, lat. '2, alt. 'I. Hah. Mazatlan ; 1 valve off Chama ; L'pool Col. Tablet 497 contains the specimen. GENUS LEPTON, Turt. Turton, Conch. Dytli. Brit., 1822, p. 61. The typical species of this genus are easily distinguished by their flat, shagreened valves, and diverging, prominent teeth. They are ranked with Arcadse by Clark, Moll. Test. Mar. Brit. p. 75 et seq. Dr. Gray constitutes for them a fresh family : while Philippi follows Forbes in locating them with Kelliadse, and Woodward unites the whole tribe to the Lucinidae. Much more must be learned of the animals of the foreign species before their true position can be ascertained. Some of the species can with difficulty be separated from Kellia by the shell alone. 157. LEPTON CLEMENTINUM, n. s. L. t. papyracea, alba, concentrice undulatd, punctulis mini- mis creberrimis confertd ; incequilaterali, subquadratd, umboni- bus magnis, prominentibus ; marginibus dorsalibus incurvatis ; dent. card, uno, celato, fossam ligamenti parvam, depressam adjiciente ; dent. lat. duobus curtis, divergentibus* Although I had the misfortune to damage the only valve found of this beautiful species, yet the characters are so well marked that it appears best to describe it. The shell is shaped like dementia, with a few stout, rather distant, concentric un- dulations : texture transparent, and exhibiting a most minute cellular structure, very evident by transmitted light. Hinge very small, with a tiny, sunken, ligament pit and a minute almost hidden cardinal tooth adjacent ; and two very short but distinct diverging laterals. The umbo is made very prom- MAZATLAN BIVALVES 111 inent by the hollowing out of the sides. Long. '025, lot. '035, alt. '02. Hob. Mazatlan ; 1 valve off Spondylus ; L'pool Col. Tablet 498 contains the specimen. 158. LEPTON DIONJEUM, n. s. L. t. papyraced, alba, subtrigonali ; lavi, striulis incrementi minimis confer tissimis : incequilaterali, marginibus dorsalibus subrectis ; cardine dent. lat. duobus curtis, prominentibus, fos- sam ligamenti kaud parvam continentibus. In the only valve found of this species, there is no cardinal tooth. The shape nearly resembles some species of Dione, with the dorsal margins nearly straight, and at right angles. It is known at once from L. Clementinum by the absence of cellular markings and concentric undulations, the place of the latter being supplied by minute crowded striae of growth. Long. '04, lat. '06, alt. '03. Hab. Mazatlan ; 1 valve off Spondylus ; L'pool Col. Tablet 499 contains the specimen. 159. LEPTON UMBONATUM, n. s.* L. t. subquadratd, subinflatd, cinered, opacd; striis incrementi, item hue et illuc liris acutis concentricis ornatd ; umbonibus par- vis, valde prominentibus ; margine ventrali compresso ; cardine dent. lat. kaud longis, excurvatis ; fossa ligamenti valde depres- sd ; impress, muse, subrotundatis. Shell Kellia-shaped, but with a small extremely prominent umbo, and a flattened ventral edge. Surface of a dull ashy colour, with an extremely thin epidermis ; rather solid, and not displaying the shagreened pattern ; with the lateral teeth short, but not so much so as in the other species, somewhat * As so little is known of this genus, I append a description of a perfect and well marked valre at present in my collection. LEPTON PLACUJTOIDEUM, n. s. L. t. planata, quadrata, subincBquilaterali, oentraliter incurva, papyracea, alba, hand punctata; liris concentricis acutis, ven- traliter undnlatis, interstitiis striis exillimis concentricis; umbonibus parvis, sed a Unea dorsali recta valde prominentibus ; fossa ligamenti parva ; dent. lat. parvis, extantibus, divergentibus, in umbone sitis, admarginem dorsalem paululum excurva- tis ; dent. card, altera in valva nullo, altera ? ; imp. muse, haud conspicuis. Hab. West Indies. Shaped like L. squamosum, but distinguished at once by the prominent umbos, incurved ventral margin, sharp concentric ridges, and absence of the shagreen pattern. Long. *07, lat. !, alt. -03. 112 MAZATLAN BIVALVES excurved ; ligamental pit in the umbo. One minute valve, (* 02 across,) and one ? adult weie found. Long. '06, lot. '08, alt. '04. Hob. Mazatlan ; 2 valves off Sppndylus ; L'pool Col. Tablet 500 contains the larger valve. GENUS PYTHINA, Hinds. Voy. Sulph. 1844, p. 70. Known by its very trigonal shape, often ventrally indented and divaricately sculptured. It must not be confounded with Pythia, Schum. 1817, = Scara- bus, Montf. : nor with Pythia, G-ray, 1821,= Conovulus myosotis, &c. = Kellia, pars, Phil. Handb. Conch, p. 344 : Woodw. Man. Moll. ii. 295. 160. PYTHINA SUBL^VIS, n. s. P. t. minima, alba, epidermide tenuissimd stramined indutd ; valde inaequilaterali, transversd, trigond, umbonibus prominen- tibus, margine ventrali seu recto seu siibincurvato ; Icevi, seu striulis exillimis divaricate radiantibus ; dentibus card, alterd valvd ii. divergentibus, quarum una major, alterd nullis ; dent, lot. elongatis, exillimis. Two pairs and two valves of this shell were found, differing in outline and sculpture, but probably identical. The character of the hinge seems more related to Montacuta than to Kellia. The smallest valve is '025 across : the largest measures long. '05, lat. '08, alt. '025. Hob. Mazatlan ; on Chama and Spondylus, extremely rare ; L'pool Col. Tablet 501 contains the two pairs, one closed, the other opened. GENUS MONTACUTA, Turt. Conch. Dithyr. Brit. p. 58, 1822. According to Clark, Moll. Test. Mar. Br. pp. 88, 94, the typical species of this genus belong to the Anatinidse, while the aberrant species remains to constitute a new family. Of MAZATLAN BIVALVES 113 the following species, only a few valves have been found. They are however described provisionally, as so little is known of the tribe. 161. MONTACUTA ELLIPTICA, n. S. JkT. t. obovali, planiuscwld, albd, marginibus undigue sa tis excurvatis ; concentrice tenuissime striatd ; umbonibus promin- entibus ; valvd alterd, fossa ligamentum recipiente, dent. card, nullo, later alibus longis, gracilibus, ad marginem adJiarentibus ; valvd alterd .....? Only 2 valves (not opposite) and one minute pair which I have not dared to open, were found of this species. The shape is very regular, and the teeth very slender. The pair is less insequilateral, but this is probably due to its youth, being only "03 across. Long. *1, lat. '13, alt. *04 Hab. Mazatlan ; off Chama and Spondylus, extremely rare ; Lpool Col. Tablet 502 contains the pair and largest valve. ' 162. ? MONTACUTA SUBQUADRATA, n. s. I M. t. oblong d, subquadratd, solidiore, flavescente seu cinered ; sulcis concentricis, creberrimis, rotundatis ; umbonibus appressis, lunuld excavatd ; valvd Alterd dent. card, uno, inter fossas duas, dent. lat. longis, prominentibus ; valvd alterd dent. card, uno, elongato, prope marginem, fossa und, latd ; dent. lat. sub" obsoletis. One perfect and two broken valves were found, which are probably conspecific. The genus is doubtful: the hinge in one valve resembles G-ouldia, and the shell is too much worn to determine the position of the ligament. It appears as though there were two cardinal teeth interlocking, with the ligament occupying the second pit : but instead of the hinge area being interrupted, the pits are on a raised plate, as in Mactra, &c. Outside it resembles in miniature some of the oval Oolitic Astartidse. Long. '1, lat. '13, alt. '03. Hab. Mazatlan ; off Chamse, extremely rare ; L'pool Col. Tablet 503 contains the large perfect valve, with the frag- ment that is supposed the opposite. 114 MAZATLAN BIVALVES 162. MONTACUTA , sp. ind. Tablet 504 contains a fragment of a stout shell, in many respects like ? M. subquadrata ; but entirely destitute of car- dinal teeth. The lunule is much incurved : indistinct ridges run from the prominent umbo to the anterior and posterior margins ; surface concentrically striated ; hinge margin inter- rupted, with large sunken cartilage pit bounded by 2 marginal callosities, but no lateral teeth. The shell when perfect was probably larger than the last. Sab. Mazatlan ; off Charna ; L'pool Col. FAMILY CYCLADIDJE. GENUS CYEENA, Lam. _| . 364. CYEENA OLIVACEA, n. s. C. t. corn-press a, subtrigond, Icevi, vel striis incre- menti Jiaud impressis, . epidermide olivaced indutd ; margine ventrali excurvato, posticum versus plerumque sinuato ; postico angulato, subrostrato ; latere dorsali antico declivo, vix alato ; umbonibus satis prominentibus, ligamento elongato ; epidermide umbones tegente, lam e His p arvis corrug atis pler- umque indutd, maxime angul am posticam versus ; intus pur- pured, maxime umbones et rnargirfem versus ; dent. card, iii., quarum alterd valvd antici duo, alterd postici duo, bifidi sunt ; lat. 2-2, 1-1, parvis, Icevibus, extantibus, quarum antici pro- pinqui, postici remoti sunt ; sinu pallii parvo, triangulari, angustissimo. = C. Fontainei, Desk. ms. in B. M. et Mus Cuming, et P. P. C. in Cat. Prov. : non D'Orb., ad fid. spec. typ. : nee Phil, in Zeit.f. Mob. 1851, p. 70, no. 93. This shell has been freely distributed as C. Fontainei, D'Orb., on the authority of M. Deshayes, who having the original types to consult, was supposed to be correct. The true C. Fontainei, however, is a more regularly formed shell, with faint concentric ribs and a glossy epidermis, and appears identical with C. placens, Hani. 1844. The species which Philip- pi has described under the same name is distinct from either : it may prove to be the following. C. olivacea is known out- wardly by its flattened form, generally peaked posteriorly ; MAZATLAN BIVALVES 115 and by the rich olive epidermis, covering the umbos, and rising into irregularly corrugated folds, which are very close' on the posterior part. The interior displays a very dark purple over the greater part of the surface. Anterior adductor very near the margin. The outline varies considerably, but not so much as in the next species. The largest specimen measures long. 2 '2, lat. 2 '38, alt. 1'26. A transverse 17, 2'05, 1'06. An inflated 1'62, 1'8, 1'16. Hob. Mazatlan ; not common ; L'pool Col. Tablet 505 contains 3 specimens much produced ventrally, slightly so posteriorly. 506, 3 do. less produced. 507, 3 do. very slightly produced, normal shape. 508, 2 do. margin regular, very' transverse. 509, 2 do. less transverse. 510, 3 do. very irregular outline. 511, 1 do. orbicular, aberrant, approaching aberrant forms of the next species. 165. CYBENA MEXICANA, Brod. and Sow. C.t." C. olivacece" simulante, sed ventricosiori, forma maxime variante, suborbiculari, subtrigond, seu elliptic a ; parte posticd seu prolong aid, sew subcarinatd, seu rotundatd ; extus albescente, umbonibus plerumque maxime erosis ; epidermidefusco-olivaced, lamellis creberrimis, non cor rug at is , plerumque detritis ; intus albd, marginibus plus minusve violaced ; dent. card, magis incequalibus, lat. magis extantibus ; sinu pallii minima, marginibus paulum divergentihus. Cyrena varians, P. P. C. Cat. prov. Pars = Cyrena Mexicana, Zool. Journ. vol. iv. p. 364. Hani. Descr. Cat. p. 94. B. M. Cat. Corbiculada, p. 260, no. 59. Var. = Cyrena altilis, Gould, Mex. fy Cal. Shells, p. 27, pi. 16, f. 5. Jun. = Cyrena fragilis, Desk. ms. in Mus. Cuming. ? = C. Floridana, Conr. Proc. Ac. N. S. Phil. iii. 1846, p. 23, pi. 1, f. I.B. M. Cat. Corb. p. 257, no. 49. The original type of this species "in Mr. Sowerby's collec- tion" appears to be lost, and the description is too meagre to separate it from its congeners : " C. t. ellipticd, ventricosd, utrinque rotundatd, antice breviore ; dentibus parvis, obtusis." Nevertheless, as it is further stated to be "outside white, with an olivaceous epidermis ; inside whitish, varied with reddish violet ;" and as it came from Mazatlan, it is fair to conclude 116 MAZATLAN BIVALVES that it is the same shell. In order, however, to include the whole of the species, a new description is appended, which 1 had drawn out under the name, C. varians, which is certainly not inappropriate. A very extreme form, also found by Mr. Darbishire in the L'pool Col., has been named C. altilis by Dr. Gould, from specimens, one of which is marked "Mexico" by Maj. Rich ; another "PMazatlan." by Col. Jewett. Some of the young shells are ticketed C. fragilis in the Cumingian Collection ; but as the name does not appear either in the P. Z. S. nor in the Cat. Corb. it has probably been merged into another, perhaps C. Floridana. Although the general appearance of these shells is sufficiently distinct from C. olivacea, yet there are many points of resem- blance between individuals. This species however, is much more variable ; almost always more ventricose ; epidermis thinner, more deciduous, of a dirty brownish olive, with the layers very close and thin, not corrugated. These layers are gener- ally abraded, as are the umbos. The anterior cardinal teeth are rather more elongated : the lateral teeth rather more elevated ; the pallial sinus is rather triangular, not so narrow as it generally is in C. olivacea. The violet colour is also of a somewhat lilac tinge, and very rarely covers the whole shell. While the outside is anything but attractive, the inside is often extremely rich and beautiful. The young shells (of which an abundance were sent, but very few of C. olivacea, jun.) vary quite as much as the adults. Of the most aberrant, suborbi- cular form, Mr. Darbishire possesses a fine swollen specimen, with the umbos not abraded, and greatly resembling (except in the epidermis and the inequality of the teeth,) the speci- men, tablet 511, of the last species. A young suborbicular specimen measures long. "95, lat. 1*06, alt. '76. A young transverse sp. ,, 1*13, 1*5, ,, '81. The largest sp. 2*15, 2'52, T46. Mr, Darbishire's sp. 1*67-, 1'74, .- 1'19. Hab. Mazatlan ; not common ; L'pool Col. Tablet 512 contains 4 specimens, very regular outline, sub- orbicular. 513, 4 do. slightly transverse. 514, 4 do. a little more transverse. 515, 5 do. very transverse. 516, 4 do., the same, slightly swollen ventrally. 517, 4 do. rather more swollen. 518, 5 do. less transverse, normal state. 519, 4 do. margin regular. 520, 5 do. subtrigonal. 521, 4 do. posterior part subangulated. 522, 6 specimens shewing the interior. MAZATLAN BIVALVES 117 FAMILY UNIONID^E. GENUS ANODONTA, Guv. Anodonta, Guv. Tabl. JEle'm. 1798. Anodon, Oken, 1815. 166. AXODONTA CICONIA, Gould. Anodon ciconia, Gould Proc. J3ost. Soc. Nat. Hist. vol. iv. p. 92, :Nov. 1851 : Hex. fy Col. Shells, p. 29. Anodon sinuata, Sivains. (as of Lam. lion A. sinuosa, An. s. Vert. vol. vi., p. 569, no. 14.) Exot. Condi, p. 29, pi. 16, edit. Hani. Distinguished from A. anserina, (Brazil,) according to Gould, by being thicker, more tumid on the posterior half, epidermis and nacre differently coloured. The nearest N. American species is A. implicata. It varies in shape, but may generally be known by its somewhat solid growth, ventral gape, and salmon colour within. In the young shell, the tint is silvery, light or flesh colour. Long. 2'32, lot. 4*24, alt. 1'46. Hal. ? Mexico, Lieut. Green. Mazatlan ; not uncommon ; Lpool Sf Havre Coll. Tablet 523 contains 3 sp. elongated form. 524, 2 sp. inter- mediate. 525, 2 sp. produced ventrally, epidermis glossy with faint radiating lines of colour. 526, 1 sp. with concentric striae near the umbos. 527, 2 sp. distorted. FAMILY MYTILID^E. Dr. Dunker is at the present time engaged on a monograph of this family, of which the first part only (Monograph of the genera Septifer and Dreissena) is as yet published. He has however most kindly identified the Mazatlan species with his own, and given me much valuable information concerning them. The young shells not only of different species, but even of different genera, very closely approximate each other. The measurements in this family are taken as follows ; long. from umbo to posterior extremity ; lat. from dorsal extremity of ligament straight across to ventral margin ; alt. thickness of closed valves. 118 MAZATLAN BIVALVES GENUS MYT1LUS, Linn. 167. MYTILUS PALLIOPUNCTATUS, DJcr. M. t. subrectd, elongatd, angustd, tumidiore, solidd, plerumque varie detritd ; rugis incrementi concentricis scepe instructd ; epidermide crassd, corned, fusco-olivaced, horridiore, radiatim tenuissime aratd, plus minusve indutd ; margine dorsali et car- dinali parum excurvato ; ligamento solido, extus umbones spira- liter ascendente ; pagind internd pulcherrime atro-purpured, splendente, apertiiram bi/ssalem versus pallidd, punctis sparsim valde i mp ressis ; cicatricibus muscularibus conspi- cuis, plerumque maxime corrugatis. M. tenuiaratus, Dlcr. ins., a prima manu. Shell long, swollen, rather straight, pointed, almost always rubbed at various angles, but when perfect exhibiting very fine radiating striulae, and sometimes much stronger concentric lines of growth. Interior of a lustrous dark purple, white near the byssus, punctured over the principal part of the surface, as in many species of Semele. In the only adult specimen observed displaying the umbos distinctly, the ligament is seen to wind towards them outside the shell, presenting an appear- ance as in some Myoconchse. The muscular impressions are strongly marked, and often very rugose. The very young shells display neither striulse nor punctures, and are scarcely to be distinguished from the smooth variety of the next species. Long. 3'5, lat. 1'38, alt. 1'3. Hab. Mazatlan; abundant, but always rubbed; L'pool # Havre. Coll.S. W. Mexico, P. P. C. Tablet 528 contains 7 sp., very young, the smallest '04 across. 529, a sp. with numerous young outside, in situ. 530, 8 pairs and a valve of successive ages, normal form. 531, 5 do. elongated. 532, 5 do. very narrow, elongated. 533, 5 sp, curiously rubbed. 534, 1 do. with one beak '26 shorter than the other. 535, 1 do. persecuted by Lithophagi about the hinge. 536, 3 do. distorted growth. 537, 2 do. mantle cleft. 538, 4 sp. jun.. shewing interior. 539, 4 do.' adult. 168. MYTILUS MULTIFOEMIS, n. s. M. t. parvd, maxime variante, sed plerumque angustd, prope cardinem tumidd, angulo perobscuro diagonali ; marqine MAZATLAN BIVALVES 119 dorsali, prope cardinem perangulato, interne semper plus minusve crenato; margine ventrali planato seu incurvo ; superficie modo liratd, liris plus minusve divaricantibus, modo striatd, seu omnino Icevi ; color e pu rp ureo, ad marginem ventralem viri di: ligamento curto, lato, effosso. Variat t. omnino viridi, planata, liris tenuibus. "Crenarum indoles Modiolam sulcatam, Lam. aliasque species in mentem vocat ; statura similis est M. Lavalleano, jyOrb. (et M. Senegalensi=variabili, Krauss) sed satis ab eo differt," Dkr. M. glomeratus, Gould, (San Francisco) is about the size of this species, but more resembles M. edulis in form, and has no crenations. This extremely changeable little shell might furnish materi- als for many species, if only a few picked specimens were examined ; but between the perfectly smooth and the deeply sulcated, the swollen and the flattened forms, there exists so regular a gradation that it is impossible to separate them. The young shell is shaped like Modiola. The smooth speci- mens closely resemble the young of M. palliopunctatus, but maybe distinguished by the presence of at least two or three denticles at the angle of the hinge line, and generally by a few more at the umbos. These may often be seen in the closed shell by transmitted light. Frequently the entire hinge line, as well as the posterior margin, is crenated. The majority of young specimens are smooth, and of adults .sul- cated ; but often very minute specimens are plicated while those of (for the species) large size are smooth. The colour is generally purple, with a larger or smaller greenish portion near the byssus ; but sometimes the purple is curtailed to a small patch, or is absent altogether. The shell is then gener- ally flat, with fine, branching furrows : and might fairly be taken for a different and well-marked species, but for inter- mediate forms. The smallest specimen found measured scarcely '02 across ; an unusually large one, long. '45, lat. *24, alt. '32. Some forms of the green variety might easily be taken for another species. Nevertheless they go through the same changes from nearly smooth to coarsely plicate, and often display purple at the commencement, or have purple at the margin. Occasionally a smooth purple shell suddenly changes to a plicate green one. The green shells are generally flatter, and often have the ribs somewhat nodulous ; in which state they are known from the young of Septifer Cumingianus by the absence of hairs on the epidermis. 120 MAZATLAN BIVALVES Hob. Mazatlan ; jun. abundant, rare adult, among sea weeds on Chainse, Spondyli, Ostrese, ^atellse, &c., or in the cavities of dead Lithophagi or Balani ; L'pool fy Havre Coll. Tablet 540 contains 5 pairs and 6 pairs of valves, smooth form. 541, 7 pairs and 6 pairs of valves, slightly lirate. 542, 11 pairs and 7 pairs of valves, lirate, jun. 543, 7 pairs do. adult. 544, 2 pairs and a valve strongly lirate. 545, 2 sp. in crevices of Balanus and Lithophagus ; another Balanus has a crab in situ ; off Patella Mexicana. 546, a group in situ among Balani, on M. palliopunctatus. 547, 2 sp. one with the surface in concentric layers, like Crepidula Lessonii ; the other with young Nullipore. Tablet 548 contains 5 pairs and 4 pairs of valves, greenish var., smooth form. 549, 7 pairs and 4 pairs of valves, finely lirate. 550, 4 pairs and 1 pair of valves, strongly lirate. 551, 1 large valve, flat and broad. Tablet 552 contains 3 pairs and 2 valves, probably belonging to this species. GENUS SEPTIFEB, Red. Vide Dunk. Com. Sep. et Dreis., Marburgh, 1855. Tichogonia, pars, Rossmassler, 1835. 169. SEPTIFEB CUMINCHI, Reel. Dunker, Monog. Sept. p. 8, no. 18. The few specimens found are too young to identify with accuracy. They are covered with fine, granulose ribs, with rather long bristly hairs rising up between. The umbonal plate is scarcely perceptible in the smallest shells. Hinge line crenate, as in M. multiformis. They closely resemble the young of S. bilocularis, but geographically agree better with the species quoted. The largest specimen measures only '16 in length. jf a l Panama, Mus. Cuming. Mazatlan ; extremely rare, jun. on Spondylus ; IS pool Col. Tablet 553 contains 3 pairs of different ages. GENUS MODIOLA, Lam. ' Volsella, Scopoli, 1777. Modiola, Lam. 1801. Modiolus, Risso, 1826. MAZATLAN BIVALVES 121 170. MODIOLA CAPAX, Conr. Journ. Ac. Nat. Sc. Phil. vol. vii. p. 242. Hani. Descr. Cat. p. 236. Modiola spinifera, P. P. C., Cat. Prov. ??Jun. Mytilus spatula, Mke. in Zeit.f. Hal. 1848, p. 2. This species having been examined at every stage, from '03 to 6*5 in length, it is possible to give a tolerable account of its history. It begins life as a small white body, shaped like Anodonta, but with the umbos very prominent and subcentral. The anterior part is then very large, the posterior very short in proportion. It soon however assumes the normal form, from which (in about 60 specimens examined) it varies but little. This differs from M. modiolus, in being slightly winged and strongly angled (about 130) at the dorsal margin, and in being very much produced posteriorly. The epidermis when young is light green and smooth ; soon it changes to a dark chesnut colour, generally developing concentric rugose irregu- lar lines, and an abundance of hairs. These, in the very young shell are long, and not serrated ; but soon they become shorter in proportion, very strong and hard, and armed on one side with sharp, rather distant serrations. The cuticle is thin, smooth and glossy on the ventral part, and inside the margin. Colour at first white, tinged with purple ; afterwards very iridescent and shaded with flesh colour and puce, with yellow near the ventral margin. Ligamental pit deeply sunken, slightly bent, bounded by a strong ridge. None of the Mazat- lan specimens were remarkable for size ; a valve however from La Paz in Dr. Gould's collection measures, long. 6' 5, led. 3", alt. 2 '5. Hob. San Diego ; in marshes and muddy shores ; Nuttall San Diego, Lieut. Green. La Paz, Col. Jewett. G-allapagos, Cuming. S. America, [?] Kellatt, in B. M. S. W. Mexico, P. P. C. Mazatlan ; rare, spinning a copious byssus, often attached to gravel or to each other, harbouring Marginella, Coecum, Eulima, Odostomia, &c. ; L'pool Col. Tablet 554 contains 10 pairs and a minute valve, various ages. 555, 2 .sp. adolescent. 556, 1 do. adult. 557, specimens of the thorny hairs. 4. 171. MODIOLA BRASILIENSIS, Chemn. Mytilus modiolus Brasiliensis, Chemn. Conch. Cab. vol. xi. pi. 205, f. 2020-1. Jan. 1856. m 122 MAZATLAN BIVALVES Modiola Brasiliensis, Hani. Desor. Cat. p. 234. DJcr. in lit. Mytilus bicolor, Brug. Cat. Modiola Guyanensis, Lam. An. s. Vert. vol. vii. p. 20, no. 4. Deles. Rec. i. 13, f. 9. Mytilus Guyanensis, Desk. Enc. MetJi. vers. vol. ii. p. 565, no. 24. = Modiola semifusca, Sow. (non Lam.) Gen. f. 6. Rve. Conch. Syst. pi. 101, f. 6. C. B. Ad. Pan. Shells, p. 251, no. 399. The typical form is remarkably constant in its characters, while the ?var. is very changeable. Shell extremely thin, very rhombic, with the ventral and dorsal lines very straight, at an anle of about 30, a well marked diagonal ridge, and a somewhat straight posterior line, at a mean divergence of about 105 from the dorsal line : with concentric furrows on the posterior part of the shell. This is coloured olive green ; while the anterior ventral part is smooth, and of an orange colour, with a narrow diagonal band of light orange, separating the two areas. Inside stained dorsally with reddish purple. Umbos not decorticated. Long. 3 '3, lat. 1'5, alt. 1*1. Hob. Brazils, Guyana, DunJcer. Venezuela, (Porto Cabello et Caraccas,) Bay of Guayaquil ; Dr. Tarns, teste Dunker. Mazatlan ; rare ; Lpool fy Havre Coll. Panama, rare, C. B. Adams. Tablet 558 contains 2 specimens, young and old. 171 1. MODIOLA ?BSASILIENSIS, var. MUTABILIS. 4. Modiola semifusca, P. P. C., Cat. Prov. ; non Soiv. ; nee Lam. An. s. Vert. vol. vii, p. 22, no. 11, (teste Hani.) Jtf. ? Brasiliensis, t. solidiore, epidermide atro-fusca induta, apicibus plerumque decorticatis ; statura minor e : forma ma- xime variante ; margine ventrali recto sen valde incurvato ; plus minusve elongata ; angulo diagonali indistinctiore ; mar- gine posterior e plus minusve excurvato. This shell suits exactly the description of Lam., but is distinct from the shell which Mr. Hanley states to be the true M. semifusca. According to Hanley, Dunker,, and the first impressions I received from an examination of the speci- mens, this may be a rough water var. of M. Brasiliensis : there is however sufficient doubt to make it desirable that the varia- tions from other recorded localities should be accurately MAZATLAN BIVALVES 123 investigated. The N. Zealand specimens appear intermediate between this and the typical form, differing from the latter in being a flatter shell, with a well rounded posterior margin. This shell appears to take all allowable forms except the typi- cal one, the margins never being so straight and angular, and the diagonal keel being less impressed. The muscular impres- sions vary somewhat, the posterior adductor being generally retort-shaped. The young shells display a fine olive spotting on a light ground in the posterior part, which is always much produced. The largest specimen (distorted) measures long. 2*5, lat. 1-2. alt. 1*1. Hob. Mazatlan ; not common ; L'pool 8f Havre Coll. ? New Zealand, Hincks. Tablet 559 contains 1 adolescent specimen, oval form. 560, 2 sp. broad, dorsal margin straight. 561, 2 do. very long. 562, 2 sp. -slightly curved. 563, 2 do. ventral margin much incurved. 564, 1 large specimen, somewhat distorted. Tablet 565 contains a valve '05 long, of a oval form, with the concentric furrows clearly marked. G-ENtis CBEKELLA, Brown. Crenella, 'Brown, 1827. Lanistes, Swains. 1840, (non Monff.) Lanistina, Gray, 1847. Myoparo, Lea, 1833. Modiola, sp. Lam. 172. CKENELLA COAKCTATA, DJcr. DunJcer in lit. JN~o. 185, 190, Mus. Cuming. Comp. Modiola Chenuanus, JfeW. = My tilus C., B. M. Cat. D'Orl. Moll. p. 84, 754. Cornp. M. opifex, Say. Shell very variable in shape, but generally very tumid, with a medial constricting line, between which and the anterior part it is nearly smooth : the rest with rather fine radiating strise, divaricating on the diagonal angle, which in adult shells is clothed with a very coarse bristly epidermis. The strige on the dorsal part, which is much hollowed by the protuberance of the umbos and the diagonal angle, are somewhat decussated. It appears to have the power of burrowing, like Lithophagus, a specimen having been so found in the umbilical portion of 124 MAZATLAN BIVALVES Murex princeps. The youngest specimen measures '05 in length. A large specimen in Dr. Gould's collection, (locality not recorded) measures (without taking into account the epi- dermis) long. '62, lat. '28, alt. "25. A long, narrow sp. '15, '06, '06. A short, transverse sp. '18, '14, '12. Hob. Gallapagos, Cuming. Mazatlan ; in Spondylus calcifer, and burrowing in Murex regius, very rare ; Lpool & Havre Coll. Tablet 566 contains 3 sp. very young. 567, 3 do. adolescent and adult, of which one displays concentric ridges of growth, like Crepidula Lessonii. GENUS LITHOPHAGUS, Megerle. Lithophagus, Megerle von MuJilf. 1811, JEnttv. p. 69 : Phil. Handb. Conch, p. 363: DTcr. Com. Sept. et Dreis. p. 2 Lith- odomus, Cuv. 1817, Regne Anim. vol. iii. p. 136. Modiola, sp. Lam. 173. LITHOPHAGUS ATTENUATUS, Desk. Modiola attenuata, Desk, in Lam. An. s. Vert. vol. vii. p. 28, no. 25. Hani. L>escr. Cat. p. 238. Lithodomus caudigerus, var., Sow. G-en. f. 3. five. pi. 99, f. 3. Known by its greatly produced, slender form, and by the incrusting beaks, which are appressed, smooth, closed exter- nally, but hollowed in the whole inner surface. Master Archer found a very large specimen, measuring long. 4 '7, lat. 1'4, alt. *96. Hob Peru, Chili, in stones, Deshayes. Mazatlan ; extremely rare, burrowing in Spondylus calcifer, Imperator olivaceus, and Murex princeps ; L'pool &f Havre Coll. Tablet 568 contains a sp. of Imperator olivaceus, broken across, and displaying a young L. attenuatus, with L. arista- tus. 569, a very young sp. '13 in length. 570, a drawing of Mr. Archer's specimen, by Master John Jackson. 174. LITHOPHAGUS CALYCULATUS, n. s. L, t. tumidiore, curtd, in dor so valde angulata ; umboni- bus appressis, inconspicuis ; parte anticd tumida ; margin* MAZATLAN BIVALVES 125 ventrali incurvo ; epidermide fused, rugis concentricis parte posterior e instruct d ; incrustatione in parte posticd solidd, in lineas duas ab umbonibus decurrente,strussagittiformibusincon- spicuis ad marginem directis ; in rostra solida prolongatd, appressa, maxima parte non excavata sed ad apicem alte effossa, quasi caly cem adkibentia. The only specimen found is in shape like L. arist. tumidior, but differs in the remarkable character of the incrustation. This lies in a solid triangular layer over the posterior part, with arrow-headed lines pointing away from the vertex of the triangle. At the sides, the coarse rugse of the epidermis are visible, ending in a diagonal line bounding the posterior part. The incrusting beaks are appressed, as in L. attenuatus, but are not hollowed within, as in that species, until the extremity, where there suddenly appears a deep cup, dividing the ter- mination into two knobs. This might at first appear as if bored into by another mollusk, but (1) the excavation is not sideways but from the outer end ; (2) the remains of the animal are fresh within ; (3) the lines of growth on the incrustation dis- play a similar outline. Long. '36, lat. '14, alt. '15. Hob. Mazatlan ; 1 sp. in Spondylus calcifer ; L'pool Col. Tablet 571 contains the specimen. -^ 175. LlTHOPHAGTJS PLUMULA, HanL Proc. Zool. Soc. 1844, p. 17. Modiola plumula, Hani. Descr. Cat. p. 239. Comp. L. Is&vigatus, JB. M. non Quoy fy Gavin. (Cape Upstart, Juices.) Comp. L. rugiferus, DJcr. in lit. Mazatlan (teste Cuming) : "differt a L. plumula forma et incrustationis indole diversa. Margines cardinalis et basalis haud paralleli, pars anterior minus inflata est. Latus basale rugis instructum est." Dun- Jeer. Spec. unic. in Mus. Cum. no. 172. The species is known by the remarkable character of the incrustation, which for the most part presents the arrange- ment of a feather in lines running out on each side from a midrib which joins the umbo to the posterior end. The in- crustations form beaks beyond the shell, appressed but not prolonged or hollowed within. Its texture is sometimes tolerably solid, sometimes in a branching network. It does not present an organized structure under the microscope, nor 126 MAAZTLAN BIVALVES is the pattern constant, though there is a general adherence to a particular plan. It often presents the appearance of grains of detritus cemented together by animal matter, these grains also covering the body of the shell much more coarsely than in L. aristatus. It is thus that the young shells can generally be separated ; the epidermal tubercles being much larger, and the concentric wrinkles stronger. The number of specimens however was not large enough to ascertain these points with precision. The differences in the pattern of incrustation do not accompany those in form. The shape presents the same two extreme varieties, gracilior and tumidior, as inL. aristatus. The parallelism of the margins also is not constant. The bur- rows are in most respects like those of L. aristatus, q. v. They are shaped like the shell, and allow very little space for the opening of the valves. The orifice is almost close to the ex- terior, and is not bilobed. The largest perfect specimen measures long. 1'86, lat. '53, alt. '5. A very tumid sp. in Mr. Darbishire's Col. measures long. 1'9, lat. '9, alt. '6. Sal). Panama, in Spondyli, Cuming. Philippines [?], Han- ley. Mazatlan ; rare in Spondyli, very rare in Chama3 and Patella Mexicana ; IS pool fy Havre Col. Tablet 572 contains 6 pairs young, the smallest "08 in length. 573, 4 sp. adolescent and adult, typical form. 574, a sp. in situ, burrowing in the attached part of the Spondylus calcifer : portions of the rock remain, which appear to have been tfcred by Pholads ; a burrow is seen of P. calva. 575, 2 fraglBnts shewing the extremities of the burrows which are more nearly round than in L. aristatus. 576, fragments illus- trating shell structure. 577, do. incrustations. Tablet 578 contains 3 sp . different ages, var. gracilior. Tablet 579 contains 1 pair and 2 valves do., var. tumidior. Tablet 580 contains a sp. with the anterior part less swollen, and the lines not parallel. + 4- 176. LlTHOPHAGUS AETSTATUS, Sol. Mytilus aristatus, Dillw. Descr. Cat. 1817, vol. L p. 303, no. 8. Solander, ms.Wbod, Ind. Test. pi. 12, f. 8. Lithodomus aristatus, Forbes fy Hani, Br. Moll. vol. ii. p. 212. Enc. Meth.Vers, pi. 221, f. 8, a, b. Le Kopan, Adans. Sen. p. 267, pi. 19, f. 2. Mytilus lithophagus striatus, J. Sow. Linn. Trans. 1804, vol. viii. p. 274, pi. 6, f. 2, 3-5. MAZATLAN BIVALVES 127 Modiola caudigera, Lam. 1819, An. s. Vert. vol. vi. p. 27, no. 23. Hani. Eec. Shells, p. 238. Phil. Ablild. Conch, vol. ii. p. 149, pi. 1, f. 5. Mytilus Bopan, Desk, in Lam. loc. cit. (note.) Lithodomus caudigerus, Sow. Gen. f. 4. Rve. Conch. Syst. pi. 99, f. 4. Litliodomus lithophagus, Flem.' Dr. 'An. p. "414. Br. Mar. Conch, p. Ill : (non auct.) Tlie Mazatlan specimens vary 'greatly among themselves, being sometimes nearly as narrow as L. attenuatus, at other times approaching in form L. cinnamomeus ; yet they offer no marks by which they can "be separated from the long known W. African species. It begins life, (as may be seen on tracing the lines of growth in the youngest specimen '035 long,) shaped like Unio nuirgaritacea, but more swollen. Soon however the anterior portion is shortened proportionally, while the pos- terior part is prolonged. The umbos from the earliest period are quite flat, and are soon covered by a slight reflexion over them from the anterior margin. The shell is extremely thin, and covered with a glossy chesnut epidermis, turned in over the margin. Soon tubercles appear in regular rows on the epider- mis, which seem to furnish the foundation for the accretion which presently commences. This accretion appears under the microscope as if formed by the agglomeration of particles of the shell into which the creature has bored. It soon covers, more or less, the whole of the epidermis, and is deposited in a thick coating at the posterior end. Here, beginning to appear generally when the shell is about ' 12 long in the form of small terminal knobs, it gradually develops into two shelly spikes, which twist more or less round each other, and are somewhat but never wholly opposite at their bases. These spikes vary greatly in size and shape, sometimes attaining nearly half the length of the shell. They may generally be seen peeping out from the orifice, which is somewhat bilobed, though not so distinctly as in Gastrochsena. When the matrix in which they burrow is not sufficiently solid, they line that part with shelly matter, which occasionally projects as a separate case, as in the British Gastrochamse. This lining is generally found where one burrow crosses another; it was not however universal when crossing the empty part of Imperator. In this shell the creature generally has the instinct to burrow through the thick sutural portion, or else down the axis. In old specimens, the burrow is- often lined with a grayish deposit, apparently 128 MAZATLAN BIVALVES intermediate in texture between the shell and the calcareous incrustation. This deposit exten is about half way down the burrow. This species and L. plumula are always found close to the outside of the matrix ; but they do not affect the same situations. In Patella Mexicana, L. aristatus is often very com- mon. In about one fifth of an aged limpet Mr. Darbishire found 13 large specimens, without reckoning empty burrows. Here however, and in Chama, L. plumula is extremely rare ; while in the thick lower valves of Spondylus it is not uncommon. The burrows are shaped nearly as the shell, with no power of rotatory motion, and very little scope for opening the valves. Traces of the foot mark are very rare. The shell, when adult, is more or less incurved ventrally, and angled dorsally ; tumid at both extremities. Shell (without epidermis and incrustation) extremely thin. The largest specimen found perfect measures long, (with the beaks) 1'56, lat. "47, alt. "4. Hob. Senegal and West Indies ; found in ballast, London roads (!), Forbes. Senegal, in shells of Balani, Adanson. Abundant in Ostrea iridescens, W. coast Africa, StutMury : do. do. Anamaboa, B. M. Guinea, Tarns. Red Sea, Dunker. St. Thomas, Sornbeclc. Mazatlan ; abundant in Chamse, Spondyli, Ostrea iridescens, Patella Mexicana and discors, Imperator unguis and olivaceus, Strombus galea, &c ; L'pool fy Havre Coll. Tablet 581 contains 11 pairs, and 8 pairs of valves, extremely young. 582, 5 pairs and 4 pairs of valves, a stage older. 583, 8 pairs and 3 pairs of valves, do. 584, 6 sp. adolescent. 585, 5 do. adult. Tablet 586 contains 6 young sp. in situ, burrowing in Patella Mexicana. 587, 1 do. do. with the beaks detached, shewing the glossy epidermis beneath. 588, 2 adult sp. in P. Mexicana. 589, fragment of P. Mexicana, displaying shelly lining to tubes. 590, another fragment, in which a Lithophagus had bored '6 beyond the inner surface ; the limpet having defended itself from its pursuer by fresh layers of shell. 591, 4 sp. of Patella discors, variously distorted by Lithophagi. 592, Fis- surella rugosa and F. alba, similarly attached. 593, Mytilus tenuiaratus, with 3 Lith. in situ : part of the mussel being broken away displays its jasper-like texture, as well as the shelly lining of the tube. 594, 3 sp. of Imperator unguis, with Lith. in situ ; in one, they have just reached the interior of the mouth ; another is bored across the apex ; the other, not finding room within, has increased its size by raising a tumulus MAZATLAN BIVALVES 129 outside. 595, Imp. olivaceus, with bore across the apex. 596, do. with 5 Lith. in situ. 597, do. with upper part broken across, shewing an inner partition made by the animal to avoid the attacks of 2 Lithophagi ; also a young Gastrochsena in situ. Tablet 598 contains extremities of shelly tubes. 599, a large number of posterior extremities, to illustrate the variations of form. 600, fragments to shew the different layers, viz. inter- nal shelly layer, medial epidermis, and external coating. LITHOPHAGTJS AEiSTATUS, var. GEACiLiOE : forma exilwrij "L. attenuatum" simulante, sed appendicibus ciirvatis. Long. 1*15, cnjus '22 appendix est, lat. '3, alt. '33. Tablet 601 contains 7 sp. of different ages. LITHOPHAGTJS AEISTATUS, var. TUMIDIOE : forma tumidiori, curtd, ad L. cinnamomeum prope accedente. Long. 1*54, cujus '35 appendix est, lat. '53, alt. '58. Tablet 602 contains 3 pairs and 1 valve, very young. 603, 3 sp. young and old. The extreme form of this ? variety was naturally regarded by Dr. Dunker as a distinct species. 177. LlTHOPHAGTJS CINNAMOMEUS, CJiemn. Mytilus cinnamomeus, Conch. Cab. vol. viii. pi. 82, f. 731. Encycl. pi. 221, f. &DesJi. Enc. Meth. Vers, pi. 2, p. 566, no. 25. Modiola cinnamomea, Lam^. An. s. Vert. vol. vii. p. 25, no. 18. Hani. Descr. Cat. p. 238. Lithodomus cinnamomeus, ~B. M. Cat. Cub. Moll. p. 45, no. 539. Lithophagus cinnamomeus, DTcr. in lit. One perfect valve only was found that could be certainly identified with this species. So weak however was the shelly matter, that on being placed in hot water the cuticle ran into shreds, breaking it to pieces. According to Dunker, the species is of wide distribution, and variable in colour, being brown, chesnut, or cinnamon. This specimen was blackish brown, about an inch long. Hob. Mauritius, Lamarck. Philippines, Dunker. Cuba, Sagra. Central America, Dunker. St. Thomas, Horn- beck Venezuela, (Porto Cabello,) Tarns. Mazatlan; ex- 130 MAZATLAN BIVALVES tremely rare, burrowing in Chama; L'pool Col. Fossil, near Rome, Lamarck. Tablet 604 contains the remains of the valve. SUB-GENUS LEIOSOLENTJS. Animal profunde in matricem penctrans, earner am capacem, politam excavans, partem derelictam explens prceter iubum Ice vein partim bilobatum, ? sipkones longos tenentem. Testa LithopJiago similis. If the animal, when examined, proves to have long, excur- rent siphons, it must take generic rank perhaps in the neigh- bourhood of Mytilimeria, Conr. 178. LEIOSOLEXUS SPATIOSUS, n. s. S. t. dactyliformi) tenuissimd, curtiori ; postice concentrice undulatd ; iimhonibus celatis ; incrustatione calcarid, tenui, cegualiter totam superficiem tegente, plerumque pustulis trans- verse conjluentibus munitd ; marginibus antice et postice rotun- datis, ventraliter subexcurvatis ; lined cardinali pr&longd., tnargine dorsali curvato, subangulato, curtissimo. Camera obovali, spatiosd, nitidissimd : tiibo nitidoplus minusve elongate, juxta cameram contracto, postice bilol'ato. Several chambers of this remarkable shell were found by Mr. Darbishire ; always in the lower valves of Spondylus, and generally open as if part of the burrow were excavated in the rock. This may account for the loss of the shells except in a single instance. In the largest specimen, presented by him to the Br. Mus., are seen two chambers, which, from the long bilobed pipe of one of them, might be taken for the work of an enormous G-astrochsena. The pipes are however perfectly smooth within, while in G-astrochama they are corrugated. The biiobation is only at the extremities, the rest of the pipe being irregularly circular, and much contracted at its .function with the cell. As there is no evidence of pallial sinus in the shell (though it may possibly exist,) it is probable that the con- traction of the siphons takes place outside the body of the animal. From an examination of a specimen broken in the line of axis of the cell and pipe, it appears that the creature begins life with the shortest possible tube and a somewhat conical cell : as it burrows deeper, it not only fills up the cor- responding posterior space with concentric layers of shelly deposit, pierced by the pipe j but also proportionally shortens MAZATLAN BIVALVES 131 the cell, leaving it of a produced ovoid. It is large enough to allow of considerable expansion and revolution of the shell within : but so far from showing marks of friction, the internal coating of both cell and pipe are very glossy. The deposit is sometimes ' 4 thick. The animal is gregarious: ten burrows having been found in one Spondylus valve, of which six appeared of more recent date than the rest, being carried across the others. One of these, in crossing a burrow of its predecessor, had obliterated one half of the valves of the dead shell, and built-in the remain- ing portion with the wall of the new cell ; another had cut across and cemented a Cumingia in the same way. The shell is short, bent, scarcely angled at the dorsal margin, well rounded at the ends, and slightly excurved in front. The hinge line is very long, with the usual sharp ridge within. It is not sufficiently fresh to display the muscular impressions distinctly. There are no proj ecting incrustations ; the deposit being thin and equally diffused. The shape of the shell is not such as would have been predicated from the form of its habi- tation ; which had given rise to many surmises, before the shell now described was found entombed, without possibility of error. This shell, which is somewhat young, measures long. 1 *5, lat. '55, alt. '47 ; its cell is *65 across. The largest cell measures long. 3*26, lat. 1*2: its tube, long. 1*6, lat. (in the middle) '3, alt. '2. Hob. Mazatlan ; extremelv rare, in attached valves of Spon- dylus calcifer ; L'pool Col. Tablet 605 contains a young shell '06 in length, which may belong to this species, though its affiliation cannot be deter- mined without a series. It may possibly be a young L. cin- namomeus. Also a fragment of a large shell. 606, Spondylus valve, containing the two largest burrows, unfortunately broken in obtaining a cast : also burrows of Gastroch&na truncata, &c. 179. LEIOSOLEJTUS , sp. ind. One specimen was found by Mr. Darbishire, differing from the rest in the following particulars. Shell much shorter, broader, and with the hinge line and dorsal margin at a much smaller angle. Cell not so smooth, with dark gray walls, scarcely polished. Pipe emerging without any contraction, but with a raised ridge within the cell. The shell being very much decomposed was unfortunately broken to pieces in extraction. 132 MAZATLAN BIVALVES Sab. Mazatlan ; 1 sp. in Spondylus ; L'pool Col. Tablet 607 contains a sketch. FAMILY ARCADE. GENUS AECA, Linn. Area, pars, Linn. Lam. Area, Swains. 184). Senilia, Gray, 1848. The Arose appear to divide themselves into two natural groups, those which live freely in sand or mud, like cockles, whose name they commonly bear ; and those which live nest- ling in crevices or affixed to rocks by a horny byssoid pedal appendage. The former have stout, regular, strongly ribbed shells, and are considered by Swainson the typical species ; the latter have irregular shells, generally with a thin or shaggy epidermis, and a more or less developed ventral gape. These, which are the typical species of most authors, form Swainson's genus Byssoarca. - 180. AECA GEANDIS, Brod. fy Sow. Zool. Journ. vol. iv. p. 365. Rve. Conch. Ic. pi. 1, f. 4. Hani. Descr.. Cat. p. 160. B. M. Cat. D'Orl. Moll. p. 82, no. 729. C. B. Ad. Pan. Shells, p. 259, no. 417. This species, the W. Pacific analogue of the East Indian A. senilis, is known from it by the greater number of ribs, (25-30) and by the teeth which are comparatively narrow. They are however wider than in A. tuberculosa. The shell in its young state is generally subsequilateral, subquadrate, often slightly insequivalve, with the epidermis for the most part smooth and persistent, displaying here and there hairs, and cancellating scales across the grooves. The ribs-are then often granulose. As it advances to maturity, the posterior part generally becomes much produced, till the aspect of the shell becomes very insequilateral, and not unlike that of A. tuber- culosa r . It may however always be distinguished from it by its greater solidity, the smaller number of ribs, and by the grooves which nearly equal the ribs in breadth. The epidermis grad- ually becomes thick and rough, forming in concentric layers, which are very conspicuous across the grooves. The umbonal portion generally becomes decorticated. The ligament is coarse and solid, filling up the whole of the hinge area except a MAZATLAN BIVALVES 133 smooth border all round. The teeth are normally numerous, strong, and nearly straight, scarcely shewing the middle point. The extreme teeth are sometimes broken into tubercles. Often however they become very small or even obsolete. Sometimes long callous processes are formed inside the line of teeth, which, when much developed while the teeth are obsolete, present a striking resemblance to the fossil genus Macrodon. Although the Mazatlan shells are not so large as those from Panama (one valve of which weighed 2'25lb, C. B. Ad.), yet a single pair weighed 3'6lb. In the following measurements, the length is taken (1) from the umbo to the middle of the opposite margin, and (2) from the middle of the hinge to the nearest point across. The fifth column gives the distance between the umbos, long. (1) long. (2) lat. alt. umb. dist. Youngest sp. transverse, '85, '73, 1*14, "7, "06. Young sp. produced, 1", '86, 1'18, '77, '1. Largest sp. 5', 3'2, 5'8, 4'7, 1*3. Ovate sp. 3'65, 2*7, 4'9, 3', '55. Inflated sp. 3'4, 2'1, 4'2, 3'8, 17. llalj. Heal Llejos, Bay of Guayaquil, &c. Cuming, Hinds. Ecuador, Guayaquil, Fontaine, D'Orbigny. Panama ; rare but large, half buried in mud and small algse, under trees, a little above half tide level ; C. B. Adams. Mazatlan ; very common ; L'pool fy Havre Coll. Tablet 608 contains 5 specimens, square form, young. 609, 2 sp. do. adult. 610, the largest sp. 611, 4 sp. young, slightly transverse. 612, 1 do. adult. 613, 1 do. large. 614, 4 sp. young, produced, shape approaching A. tuberculosa. 615, 1 do. adult. -616, 4 sp. transverse. 617, 4 sp. gibbous, young. 618, 1 do. adolescent. 619, 2 do. adult. Specimens exhibiting the inside. Tablet 620 contains 3 sp. young. 621, 1 do. valves interlocking. 622, 1 do. adult, broad teeth, "Macrodon" processes distinct. 623, 1 do. hinge nar- rower, callosity within, running from umbo. 624, 1 do. hinge and processes developed, margin in layers, probably from intrusion of dirt. 625, 1 do. teeth obsolete, processes distinct. 626, 1 do. hinge line narrowed off, teeth only shewing at ex- tremities. 627, 1 do. posterior hinge margin fractured and partially mended, shewing the teeth of an earlier age. Feb. 1856. n 134 MAZATLAN BIVALVES 181. AECA MULTICOSTATA, Sow. Proc.. Zool. Soc. 1833, p. 21. Rve. Conch. Ic< pi. 4, f. 23. Hani. Eec. Shells, pi. 19, f. 12. One very fine specimen of this shell was found by Mr. Archer. It differs from A. grandis in being much lighter, with more numerous ribs, and a squarer form. Long. 2 '65, lat. 3 '16, alt. 2 '36. Hob Gulf of Tehuantepec, 12 fm., Cuming Mazatlan ; ex- tremely rare ; Lpool Col. Tablet 628 contains a very small valve, '15 across, which may belong to this species. 629, a drawing of Mr. Archer's specimen. 182. AECA PLABIATA, Sow. Proc. Zool. Soc. 1833, p. 21. Eve. Conch. Ic. pi. 1, f. 7. Hani. Descr. Cat. p. 160. .5. M. Cat. DOrb. Moll. p. 81, no. 720. Comp. A. labiosa, Soiv. loc. cit. live. Conch. Ic. pi. 10, f. 67. Hani. Descr. Cat. p. 159, pi. 19, f. 3. B. M. Cat. DOrb. Moll. p. 81, no. 720. Comp. A. incongrua, Say, Journ. Ac. Nat. Sc. Phil. vol. ii. p. 26$. Hani. Descr. Cat. p. 159. The three species above quoted are very nearly allied. The two specimens found in the L'pool Col. by Messrs. Hibbert and Archer, before it fell into the dealer's hands, are exactly Kke the specimens brought from Florida, by J. J. Au-dubon. Shell with distant beaks, and strong ligament filling up a large rhomboidal area. Shape subangular ; tubercles absent from the angular part, also from the front of the smaller valve. Teeth rather broad. Long, (fromumbo) 1'23, lat. 1 '3, alt. 1'04. Hob. Eeal Llejos and Tumbez, Peru, in sandy mud, 7 fm, Cuming. Mazatlan ; extremely rare ; L'pool Col. Tablet 630 contains a specimen, presented by J. Hibbert, Esq. 183. AECA BIFEOXS, n. s. A. t. turgidd, subquadratd, tenui, maxime incequivalvi, postice angulatd, umbonibus hand distantibus ; alba, epidermide I & v i , olivaced indutd ; costis circiter xxx., in testa junior e omnibus tuberculosis ; in adultd solum viii. x. anticis, religuis Icevibu* : costis ventralibus in v alv d m in ore p arvis , rotund at is 9 MAZATLAN BIVALVES 135 interstitia hand cequantilus ; in valvd majoreplanatis, subobsoletis, interstitiis minimis ; ligamento solido, aream rhom- boideam implente ; dent. card, in lined curvd, parvis ; marginc valvtz majoris ejffosso, valvam alter am reeipiendo ; co stilus prop - ter tenuitatem intus monstrantibus. The above description is written from three beautiful ex- amples in the Museum of Hugh Cuming, Esq. Fragments only of young shells were found in the L'pool collection, which however probably belong to the same species. It is known from A. incongrua and its congeners by its light structure, smooth epidermis, and especially by the ribs which are very narrow on one valve with wide interstices, on the other broad and flat, scarcely divided. There is a corresponding difference in the crenations of the valves. Long. 1*55, lat. 1*73, alt. I' 32. Hob. Mazatlan, Mus. Cuming. Do ; fragments on Spondylus calcifer ; L'pool Col. Tablet 631 contains the fragments. \- 184. AECA TUBERCULOSA, Sow. Proc. Zool. Sac. 1833, p. 19Miill. Syn. Test. Viv. p. 179. Phil. Abbild. I. pi. 1, f. 2.Rve. Conch. Ic. pl.-3, f. 18. Hani. Descr. Cat. p. 161, pi. 18, f. 53. C. B. Ad. Pan. Shells, p. 263, no. 425. Comp. Area similis, C. B. Ad. Pan. Shells, p. 262, no. 422. Shape varying from subquadrate, subsequilateral, to very transverse, with the posterior part much produced ; sometimes flattened, sometimes extremely swollen. Bibs very numerous (about 36), close, slightly and irregularly tuberculous, often shewing concentrie ridges of growth. Epidermis dark brown, coarse, deciduous near the umbos, with short scaly hairs in the intercostal spaces, and sometimes finer hairs on the pos- terior part. Inside white : teeth numerous, rather broad. Ligament coarse, solid, entirely filling up the rather narrow area between the beaks. Hinge line sometimes rounded off. The largest specimen measures long. 2 '78, lat. 3*67, alt. 2 '5. A squarish 2', 2*35, 1*5. A swollen 2'45, ,,3', 2'35. Hab Real Llejos, at roots of Mangrove trees, low water, Cuming. Panama, in impalpable mud, under a Mangrove thicket, near high water mark, not uncommon, C. B. Adams. Mazatlan ; very common j L'pool fy Havre Coll. 136 MAZATLAN BIVALVES Tablet 632 contains 2 spec-mins, squarish form. 633, 5 do. fine flattened growth. 634, 5 do. normal growth. 635, 3 do. swollen, produced. 636. 3 do. swollen, oval. 637, 4 sp. shewing the inside, one normal, another with the anterior teeth irregu- lar, the third with the teeth nearly obsolete, the fourth do. quite obsolete, apparently from disease. 185. AECA EEVEBSA. G-ray. Sow. in Proc. ZooL Sac. 1833. p. 20 Mull. Syn. Test. Viv. p. 180. Eve. Condi. Ic. pi. 1, f. 5.B. M. Cat. D'Orb. Moll. p. 81, no. 722. C. B. Ad. Pan. Shells, p. 261, no. 421. Area hemicardiuni. Kocli in Phil. Abbild. pi. 1, f. 1. 1843. This aberrant species is known at once by the truncation of the anterior portion. The ligament is cut off at right angles between the umbos, (which are not distant) and is solid, occu- pying the posterior area. The posterior line of teeth begins from the umbo ; the anterior begins from a point nearer the middle, lying within the other, and is very short. There is a slightly developed ridge bounding the anterior adductor, as in Cucullaea. Long. I' 7, lat.2'15, alt.~L'5. Hob. Turnbez, Peru, in soft mud, 7fm., Cuming, D'Orbig- ny. Panama, extremely rare, C. B. Adams. Mazatlan ; 2 fine specimens only were found by Mr. Archer ; L'pool Col. Tablet 638 contains one specimen. 186. AECA PBEEVIFEONS, Sow. Proc. ZooL Soc. 1833, p. 22Rve. Conch. Ic. pi. 1, f. 6. In consequence of the internal characters not being given, the species cannot be determined with accuracy^ but it fits the description as far as it goes. Epidermis as in A. multicostata, very finely striated along the radiating ribs, coarsely rugose between. Unibos approximate ; ligament very long and nar- row. Inside white, with a subumbonal stain as in A. emar- ginata. Posterior hinge teeth in a long slightly curved line : anterior somewhat twisted, in a short line at a decided angle. The teeth resemble A. reversa. Long. '59, lot. "48, alt. '33. Hah. Tumbez, Peru ; in soft mud, 7 fm. ; Cuming. Mazatlan ; 1 sp. on Murex nigritus, with A. eniarginata ; L'pool Col. Tablet 639 contains the specimen. MAZATLAN BIVALVES 137 187. ARCA EMAROINATA, Sow. Proc. Zool. Soc. 1833, p. 20. Mull. Si/n. Test. Viv. p. 180. Eve. Conch. Ic. pi. 4, f. 2Q.Hanl. Dcscr. Cat. p. 161, pi. 18, f. 60. J?. M. Cat. D'Orl. Moll p. 81, no. 723,- C. B. Ad. Pan. Shells, p. 258, no. 415. Although classed by Sby. among the sequivalves, he rightly describes it as insequivalve, the posterior ventral part consider- ably overlapping, even in young shells. Umbos separated by a narrow triangular area. Ligament in very young shells only adhering posteriorly : afterwards filling a triangular space to the beaks ; when adult displaying also a thin film on the anterior portion. Teeth strong, not very numerous, both rows forming a regular, slightly curved line, not reaching into the wing. Emargination not developed in young shells, variable in adult. Very young shell smooth : afterwards beautifully coloured with irregular dark chocolate undulating bands, and an interior spot radiating from the umbos. The smallest specimen is '03 across : the largest (valve) long. '5, lat. '9, alt. "35. Hob. Atacamas, Real Llejos, Xipixapi, Panama ; in sandy mud, 6-8 fm. ; Cuming. Do. ; D' Orbigny. Panama, very rare ; C. B. Adams. Gulf of California, Mus. Cuming. Mazatlan ; young on Spondylus calcifer, adult on Murex nigritus, extremely rare ; L'pool Col. Tablet 640 contains 4 sp. young. 641, the largest valve. 188. ARCA , jun., sp. ind. Comp. Byssoarca alternata, Sow. Proc. Zool. Soc. 1833, p. 17. (Area a.) C. B. Ad. Pan. Shells, p. 257, no. 413. (Hob. W. Columbia, Cuming : Panama, C. B. Adams : Mazatlan, Col. Jewett.) Tablet 642 contains 2 small opposite valves, the largest '06 across, remarkable for the structure of the hinge, which is bounded not by one but by two lines, one of which radiates from the umbo, and between which probably the ligament is fixed. Outside are concentric irregular lines near the umbo, afterwards about 40 well rounded regular ribs, with equal interstices and strong plications within. It is clearly a young shell ; too young to determine even the generic section with confidence. Hob. Mazatlan ; off Spondylus calcifer, extremely rare ; L'pool Col. 138 MAZATLAN BIVALVES GENUS BYSSOAECA, Swains. Area, sp. typ. Linn., auct. Cibota, Brown. Daplme, Poli. Navicula, Blainv. 1818 (teste Gray.) non Spix Byssoarca. Swains. 1835.* 189. BYSSOAECA PACIFICA,. Sow. Proc. Zool. Soc. 1833, p. 17. Area Pacifica, Eve. Conch. Ic. pi. 11, f. 75. Hani Rec. Shells, pi. 18. f. 595. M. Cat. D'Orb. Moll. p. 8 2, no. 735. This magnificent species is known from B. Nose and its congeners by its very large size, extremely swollen develop- ment of the posterior portion, coarse ribs, large indentation near the posterior hinge-angle, and the strong laminated gill- like epidermis, which lies in very conspicuous striated folds round the large byssal opening. It varies greatly in shape, sometimes not displaying the above characters, but presenting a tolerably uniform outline and small pedal opening. The byssal foot has a hard horny case, grooved inside. It scarcely pro- jects beyond the shell. Teeth extremely numerous, sharp, generally narrow, sometimes rather broad. Ligament very thin, distributed in a lozenge over the whole area except the margin, with coarser lines radiating from the umbos, and sometimes others irregularly crossing these. The smallest of the specimens measures long. '77, lat.l'A, alt. '8. A narrow sp. 2'2, 3'6, 2'8. The largest sp. 3', 5'5, 4*. This sp. measures inside from middle of hinge to ventral margin 1*3 ; from posterior end do. 2*4 ; projection of umbos 1*2 ; distance between umbos 1'8. Hab.St. Elena ; on rocky ground, 6-18 fm., adhering to each other in large bunches ; Cuming. Ecuador, St. Elena, jyOMgny. Bijooga Is. Capt. Beaufort, B. M. Mazatlan ; rare, but very fine ; IS pool Col. Tablet 643 contains 1 valve, '03 across, probably belonging to this species. Tablet 644 contains 2 sp. young. 645, 2 sp. adolescent ; 'Macrodon' teeth, branching from the centre, very conspicu- ous on one side ; in the larger sp. the hinge teeth are abnor- mally broad. 646, sp. not produced, incrusted with coral. 647, the largest sp. 648, stone incrusted with Bryozoa, with byssal foot attached. * Mr. A. Adams names these shells Area, and the previous species Scapharca, Gray. MAZATLAN BIVALVES 139 190. BYSSOABCA MUTABILIS, Sow. Proc. Zool. Soc. 1833, p. 17. Area mutabilis, Sve. Condi. Ic. pi. 13 f. 85. Hani. Descr. Cat. p. 156, pi. 18, f. 52.^. M. Cat. D'Orb. Moll. p. 82, no. 733. C. B. Ad. Pan. Shells, p. 259, no. 418. Compare Area Americana, D'Orb. (non Gray,) B. M. Cat. D'Orb. Moll. p. 80, no. 714 (Brazils) : B. M. Cat. Cuba Moll. p. 43, no. 521. ?=A. imbricata, Brug. (Jamaica, C. B. Ad. ; ]N"atal, B. M.) A very similar, perhaps identical species is from Australia, Juices. Shell greatly resembling the European B. tetragona, but dif- fering from it as follows. Epidermis in B. tetragona hairy, even on the angular ridge ; in B. mutabilis sublamellose, as in B. Pacifica, with the lamellar portions gill-like. Ligament in B. tetragona scarcely shewing over the area, but with numer- ous diamonds between the umbos ; in B. mutabilis darkly diffused over the whole area, with or without one or two dia- monds at the unibos. Teeth in B. mutabilis very numerous, as in B. Pacifica ; in B. tetragona larger and fewer, somewhat remote. Posterior portion in B. mutabilis strongly ribbed ; in B. tetragona, like the rest of the shell. It is distinguished from the young of B. Pacifica, which it very much resembles in form, by the posterior ribs and the epidermal ridge along the posterior angle. Pedal gape generally large. In young shells the structure under the glass is very beautiful. I am unable to find any constant character by which the West Indian specimens can be separated from it, though the shape some- what differs ; and the smaller ribs are more imbricated. The same form is from Natal, B. M. Among the best characters to distinguish Byssoarks are the form and nature of the ligament, the hinge teeth, and the epidermis. The markings and outline, as well as the inter-umbonal space, often vary considerably in the same species. The more constant characters are how- ever often overlooked in descriptions. Long. *8, lot. 1*35, alt. '72. Sab. Isle of Plata, under stones, Owning. Ecuador, Tf Orb- igny. Panama and Taboga ; not uncommon under stones and in the crevices of rocks, near low water mark ; C. B. Adams. Mazatlan ; rare : L'pool Col. Tablet 649 contains 7 specimens differing in age and shape. 140 MAZATLAN BIVALVES 191. BYSSOABCA FCJSCA, Brug. Area fusca, Brug. Diet. no. 10. D'Avila, Cat. vol. i. pi. 7, f. ~R,.Encycl. pi. 308, f. &. Dillw. Cat. vol. i. p. 231, no. 14. Lam. An. s. Vert. vol. vi. p. 466, no. 14. five. Conch. Ic. pi. 12, f. 82. B. M. Cat. Cuba Moll. p. 43, no. 523. Area barbata, var. G-mel. p. 3307. ScJirot. Einl. vol. iii. p. 279, no. 2 List. Conch, pi. 231, f. ffi.G-ualt. Test. pi. 90, f. B. Chemn. Conch, vol. vii. pi. 54, f. 534. Area bicolorata, Chemn. Conch, vol. xi. p. 243, pi. 204, f. 2007. Dillw. Cat. vol. i. p. 230, no. 11. The presence of this well-known East Indian shell in the Mazatlan fauna is very suspicious. I took one fresh pair, and Mr. Darbishire another, out of the Byssoarca box. when I first examined the Collection. As it is said to reach the West In- dies, it may linger also in the Gulf seas ; or these specimens may have come over on ship bottoms or drifting timber, or in ballast ; or they may, in some unaccounted way, have found an entrance into their appropriate box by an accident of the owner's. A small oyster attached is not distinguishable from the Mazatlan species ; but this does not prove much. Long. 1'24, lat. 1'98, alt. '97. Sab. Madagascar and Barbadoes, Lamarck. "Singapore," abundant, P. P. C. Barbadoes, (young valves) IP. P. C. Cuba, Sagra. Mazatlan : extremely rare ; L'pool Col. Tablet 650 contains the specimen I found. 192. BYSSOABCA VESPEETILIO, n. s. B. t. oblongd, compressd, postice tumidiore, expansa ; valde incequilaterali, marginibus subrotundatis, hiatu pedis modico, margine ibi incurvo ; umbonibus subappressis, ligamento Iongo 9 angusto, antice brevi ; superjicie radiatim striatd, y "02, greatly varying in outline. The teeth are at first very few in number, and the internal ridge rather prominent. 654, a young pair nestled, in situ, in fragment of Spondylus calcifer ; also 2 dried byssal feet. 655, 6 sp. young. 656, 8 adult sp., various shapes. Two sp. will also be found in situ on Chaina (tablet 411.) 195. BYSSOARCA SOLIDA, Sow. f Proc. Zool. Soc. 1833, p. IS.Milll. Syn. Test. Viv. p. 186. Area solida, Rve. Conch. Ic. pi. 16, f. 106. Hani. Descr. Cat. p. 155, pi. 18, f. 54. B. M. Cat. D'Orb. Moll. p. 81, no. 716. C. B. Ad. Pan. Shells, p. 262, no. 423. This iinpretending species greatly resembles our B. lactea, and a similar W. Indian species ; but differs from each by well marked characters. In this, the ligament is in a very narrow rhombus ; in B. lactea, in a broad one ; in the West Indian it fills nearly the whole area. In B, solida, the hinge teeth are nearly or quite obsolete within the ligament, even in young shells ; in the other two species the teeth are in an uninterrupted line. The surface also in B. solida is generally decussated with concentric tubercles ; but this character is not constant. Shape either flattened and produced, or short and much swollen. Epidermis brown, thin. Byssal foot extremely thin ; ventral margin not perceptibly gaping. A finely grown specimen measures long. "35, lat. '56, alt. '28. A swollen sp. '34, '47, '43. The largest sp. '46, '67, '46. JTab Under stones at Payta, Peru, Oumwig, IfOrbigny. Panama and Taboga ; not uncommon under stones near low water mark ; C. B. Adams. Mazatlan ; not uncommon ; L'pool Col. Tablet 657 contains 5 pairs and 1 valve very young, the latter '03 across ; one pair is strongly decussated. 658, 5 sp. scarcely decussated. 659, 3 do. flat growth. 660, 3 do. with former margins projecting. 661, 3 do. swollen. 662, 3 do. very much swollen, umbos distant. 663, 3 sp. shewing the interior. 144 MAZATLAN BIVALTES GENUS PECTUNCULUS, Lam* 196. PECTUNCULUS INJEQUALIS, Sow. Proc. Zool. Soc*1832, pt. ii. p. 196 : [non Gray in Beech. Voy. p. 152, pi. 42, f. 3 : V. Rve. in P. Z. S. 1843, p. 79 ;) nee Krauss, Sudafr. Moll. p. 18.] Hani. Descr. Cat. p. 166. Eve. Conch. Ic. pi. 4, f. 16. = P. Pectiniformis, Wood Suppl. pi. 2, f. 11, non Lam. (teste Hani.) ? = P. assimilis, Sow. Proc. Zool. Soc. 1832, pt. ii. p. l^.Mull. Syn. Test. Viv. p. 189. Eve. Conch. Ic. pi. 4, f. 15. 5. M. Cat. DOrb. Moll. p. 80. no. 712. C. S. Ad. Pan. Shells, p. 256, no. All Hani. Descr. Cat. p. 167, note. Only two specimens having been found adult of this ex- tremely beautiful shell, no opportumiy existed for ascertaining its power of variation; but C. B. Ad. thus remarks of P. assimilis, "In respect of colouring (no two being alike) the species does not appear to be well distinguished from P. insequalis : nor is the distinction in sculpture much more con- stant." Surface of the shell with a variable, small number of ribs, covered, as well as the interstices, with fine ribs decussa- ted in the "strung fig" pattern. Margin most beautifully crenated by each ; interior surface covered with fine lines ; anterior part short, ligament subtruncated. A very young valve, '04 across , displays 3 teeth on each side, with the larger ribs only developed outside and decussated : ligament in a pit as in Limopsis. Long. 1'33, lat. 1*31, alt. '9. Hob. Bay of Panama and Real Llejos ; in sandy mud, 10 fm. ; Cuming. Mazatlan ; extremely rare ; Ifpool Col, (P. as- similis) Puerto Portrero, Bay of Guayaquil ; in sandy mud and gravel 8-12 fm. ; Cuming. Ecuador, Guayaquil, I? Orb- igny. Panama ; under stones, in calcareous gravel, between one-quarter tide and low water mark, rare ; C~B. Adams. Mazatlan, Lieut. Green. Tablet 664 contains the smallest valve. 665, the finest specimen. 197. PECTUNCULUS ? MULTICOSTATUS, Sow. Proc. Zool. Soc. 1832, pt. ii. p. 195. Eve. Conch. Ic. pi. 5, f. 26 Hani. Descr. Cat. p. 165, pi. 19, f. 36. #. M. Cat. DOrb. Moll. p. 80, no. 711. * " The first name for these shells is Axinsea, Poll. If Pectnncnlus, Lam. (not Adansori) is to be used, it should be limited to the ribbed species." A. Adams, ms. MAZATLAN BIVALVES 145 Tablet 666 contains a young valve, '07 across, which may belong to this species. It is however white, with about 30 rounded ribs ; inside with a remarkably straight hinge line. Hab. Ecuador, Guayaquil, _D' Orbigny. ? Mazatlan ; 1 valve, off Chama ; IS pool Col. FAMILY NUCUUDJE. GENUS JSTUCULA, Lam. Nucula, Lam. 1801. Poly donta, Megerle, 1811. . 198. NUCULA ? EXIGUA, Sow. Proc. Zool. Soc. 1832, p. 198. Mull. Syn. Test. Viv. p. 192. Sow. Condi. III. no. 34, pi. 16, f. ZkHanl. Descr. Cat. p. 172 B. M. Cat. DOrb. Moll. p. 79, no. 704. C. B. Ad. Pan. Shells, p. 255, no. 409. Tablet 667 contains one very young valve, '03 across, which may belong to this species. The concentric grooves are just forming at the margin. Hab. Bay of Caraccas, in sandy mud, 9 fm. ; Cuming, D'Orb- igyiy Panama, 1 valve, C. B. Adams. Mazatlan ; 1 valve off Spondylus calcifer ; L'pool Col. GENUS LEDA, ScJmm. 199. LEDA ? ELENENSIS, Sow. Nucula Elenensis, Proc. Zool. Soc. 1832, p. 198 Mull. Syn. Test. Viv. p. 191. Sow. Conch. III. no. 19 pi. 15, f. l^.Rve. Conch. Syst. pi. 85, f. U.Hanl. Descr. Cat. p. 169. C. B. Ad. Pan. Shells, p. 254, no. 408. Leda Elenensis, B. M. Cat. DOrb. Moll. p. 63, no. 554. Tablet 668 contains a minute valve, '06 by "04, which may belong to this species. Transparent, concentrically grooved, but (as in C. B. Adams' specimens) margin not crenulated. Hab. St. Elena, in sandy mud, 6 fm. Cuming, D' Orbigny. Panama, rare, C. B. Adams. Mazatlan ; 2 valves off Spon- dylus calcifer ; L'pool Col. Feb. 1856. o 146 MAZATLAN BIVALVES FAMILY AVICULID.E. GENUS PINNA Linn. The remarkable similarity in form between the young shells of Isognomon and those of this genus, confirms the opinion of Dr. W. B. Carpenter (Br. Assoc. Rep. 1833, p. 20,) and, Prof. E. Forbes (Br. Moll. vol. ii. p. 250,) that it ranks in the present family. An abundance of large Pinnae, sent in the Liverpool Col., were unfortunately sold off at once to the keeper of a tea garden, where they may be seen built up into the walls, and too much disfigured to allow of the species being identi- fied. To add to the confusion, an importation of large Pinnae from New Guinea having reached Liverpool at the same time, were mixed with them, both in the shop, and in the garden walls ; and some have found their way into collections as though from Mazatlan. A similar confusion seems to have attended the Pinnae sold in London with the Havre Col., on some of which the attached Vermetidae, corals, &c. clearly prove that they came from far distant seas. The three follow- ing species are all that can be quoted with certainty as having been found in the Mazatlan boxes. Another species, like P. maura, but remarkable for its extreme breadth and thickness and for the shape of the anterior muscular impression which displays a series of ripples, was sent in the S> W. Mexican collection. Some species of this genus alter considerably in the shape of the posterior extremity, as they attain maturity. The measurements are taken as in Mytilidae. 200. PINNA MATTKA, Sow. Proc. -Zool. Soc. 1835, p. 84. Hani. Descr. Cat. p. 255. C. B. Ad. Pan, Shells, p. 250, no. 395. Adolescent shell dark brown, with about 18 rows of irregu- lar scales, here and there almost tubular ; dark brown ; pos- terior end produced, margin rather straight, ventral edge smooth, slightly inflated ; hinge line incurved near the umbos ; anterior impression bilobed. Long. 8 '5, lot. 4' 5, alt. 1*58. Sab. Panama, in muddy banks, Cuming, Do., extremely rare, C. J3. Adams. Mazatlan ; probably common, as Lieut. Belcher (Zool. Journ. vol. iv. p. 362) speaks of the large and dangerous shoals of Pinnae in the harbour, which cut boats with their sharp edges ; L'pool Col. Tablet 669 contains one of the very few specimens saved. MAZATLAN BIVALVES 147 J__ 201. PINNA LANCEOLATA, Sow. Proc. Zool. Soc. 1835, p. 84 Hani. Descr. Cat. p. 256. Shell, when extremely young, nearly smooth with a very long hinge line, but much shortened posteriorly : gradually developing radiating ridges, 8-10 in the adult, which become furnished with regular rows of long, almost tubular spines, extremely thin, light horny brown, ventral part swollen and smooth, with the margin rounding off posteriorly till it meets the dorsal line at right angles. Hinge line often incurved near the umbos. The smallest specimen found is 1' 75 long; the largest, long. 4 '2, Idt. 1*7, alt. (with spines '77, without) 28. Hab. Puerto Portrero ; in sandy mud, 13 fm. ; Cuming. Mazatlan ; in fine sand, not uncommon ; L'pool Col. Tablet 670 contains 3 sp. very young. 671, 2 do. older, with few rows of spines developed. 672, 4 do. ordinary state. 673, 2 do. crowded with tubercles. 674, 1 do. distorted growth. 202. PINNA PEUGOSA, Sow. Proc. Zool. Soc. 1835, p. 84 Hani. Descr. Cat. p. 256. P. rugosa, jun., teste Cuming. About a score of specimens were found with P. lanceolata, presenting the following characters. Shell extremely thin, very light horn coloured, transparent, glossy, with the cell- structure so large as to be visible to the naked eye, giving a peculiar texture to the surface ; very long and narrow, ventral part not inflated ; with about 6 strong ribs, traceable from the umbos, and scarcely ceasing at the ventral part, armed with large, distant, nearly tubular spines, The smallest speci- men is 1*9 long; the largest, long. 4*8, lot. 2', alt. (with spines 1*2, without) '64. Hob. Isle of Bey, Bay of Panama, on sand banks, Cuming. ? Mazatlan ; very rare ; L'pool Col. Tablet 675 contains the smallest and the largest specimens. GENUS AVICULA, Klein. Avicula, Klein, 1753 -.Brug. 1789 :Lam. 1799. Pteria, Scopoli, 1777 \-Gvay, 1847. 148 MAZATLAN BIVALVES 203. AVICULA STEKNA, GrOuld. Proc. Bost. Soc. Nat. Hist. Nov. 1851, vol. iv. p. 93 : Hex. $ Gal. Shells, p. 31, pi. 16, f. 7. C. B. Ad. Pan. Shells, p. 250, no. 392. Avicula Atlantica, Menke, Zeit.f. Mai. 1847, p. 187, no. 45 ; non Lam. ''Has the general appearance of A. semisagitta, Lam. but the wing is less oblique, and curves directly into the cauda without any sinus ; the byssal sinus is deeper and much more acute, making a trapezoidal auricle. It most nearly resembles a Florida species ; but in that the byssal angle is obtuse, the auricle triangular, and the cauda shorter." Gould* The hinge line is generally extremely long, but sometimes so short that the anterior are rather larger than the posterior auricles. Shell very insequivalve. Outer layer of shell dark chocolate, rarely slightly rayed with white. Surface almost smooth, with very fine concentric lines of growth. Epidermis in fine strongly ser- rated, closely folded laminae. Hinge teeth, card. 2-1, lat. 1-1. The pallial line is traceable from the large bilobed posterior adductor to the small anterior, situated just below the cardinal teeth. A peculiar species of Balanus is commonly found on this shell, and on the related W. Indian species. Many speci- mens of Discoporsea intricata, and eggs of G-asteropods were also found attached. The smallest sp. is *05 in length ; the lar- gest 1'24. A normal sp. measures long. '98, lat. 2 '5, alt. '42. One with short hinge T23, 1*7, '59. Hob. Panama, Col. Jewett, Do. ; very rare, attached to a small species of G-orgonia, at the low water mark of the spring tides ; C. B. Adams. Mazatlan ; not uncommon ; Col. Tablet 676 contains a minute valve, *05 long, with the lateral tooth conspicuous. 677, 7 young pairs of different sizes, (one with egg cases) and a valve shewing spotted umbo. 678, 4 sp. adult. 679, 3 do. shewing interior. 680, 4 sp. different ages, with the 'ear,' 'wing' or 'tail' very much shortened; the larger with Discoporsea intricata. * Dr. Gould's * wing"/ appears to be the body of the shell ; his 'cauda' what is by others called the wing or the ear. MAZATLAN BIVALVES 149 SUBMENUS MARGAEITIPHOBA, Meg. Megerle v. MuJilfeld, 1811. Meleagrina, Lam. 1819. 204. MAEGABITIPHORA MAZATLANICA, Hani. Meleagrina Mazatlanica, Hani. Rec. Shells, pi. 24, f. 40. No synonyms of the Pearl-oyster are given, as the question of the specific identity of the local types is not yet settled. The Gulf of California used to be celebrated for its pearl fishery, but it appears to have been exhausted, and very few oysters have been brought of late years. The specimens from S. W. Mexico appeared to belong to the Panama type, being small, produced and of a purplish brown. Of this shell in 1851 a single vessel brought 340 tons to Liverpool (T. C. Archer.) The other local types are the silver-lipped from the Society Is. and the black-lipped from Manilla. Which of these is the true M. margaritifera of Lam. has not yet been settled. In Hani. Descr. Cat. are also quoted, p. 264, M. radiata from the ? W. Indies, and M. albina from Australia. Mr. Nuttall found a pretty little species, quite distinct from the young of M. margaritifera, at the Sandwich Is. Pearl-oysters are also found at Madagascar, Persian Gulf, Ceylon, Swan Biver, &c. Very few specimens were sent in the Mazatlan collection, and of these only the young ones were preserved. Shell in that state transverse, not produced ventrally, one valve only pierced for the byssus, swollen at that part, else flat, spreading ; with closely set overlapping laminse, extremely thin, produced into foliations or flat spines ; inside silvery white, nacre bor- dered with green, margin broad, of a light tortoiseshell colour. Long. 3'55, lat. 4'05, alt. T27, (jun.) Hab. Mazatlan ; very rare ; L'pool fy Havre Coll. Tablet 681 contains a very young valve, '05 across, of nearly normal shape, known from the young of the neighbouring species by the enormous size of the prismatic cells. 682, the specimen above measured. GENUS ISOGNOMOIST, Klein. Isognomon, Klein, 1753 : DJcr. in Moll. G-uin. Melina, Retz, 1788, Diss. p. 28 -.Sckum. 1817. Perna, Brug. 1792 Lam. 1801 : (non Eetz.) Sutura, Meg. v. Mulilf. 1811. Entw. p. 65. 150 MAZATLAN BIVALVES Some confusion has arisen in this genus as in Pinna from a large number of the Malleus-shaped species from JN"ew Guinea having been brought at the same time with the Mazatlan collection, and having found their way into museums as though from this locality. The variations of form in these were most extraordinary. 205. ISOGNOMON CHEMNITZIANUM, D'Orb. Perna Chemnitziana, D'Orb. Saqra, Cuba, vol. ii. p. 346. B. M. Cat p. 46, no. 547. Perna flexuosa, Sow. ms. in Coll. Kellett, Mus. Pract. G-eol : (do. Panama, Lieut. Wood, Bristol Mus.) = Perna, sp. ind. (a), C. B. Ad. Pan. Shells, p. 250, no. 393. Comp. Isognomon Perna, Linn, in DJcr. Moll. Guin. no. 116, pi. 8, f. 7-10: = (teste DJcr.) Ostrea perna, List. Conch. Tab. 199, f. 33. Chemn. Conch. Cab. vol. vii. p. 252, pi. 59, f. 580. Schroet. Einl. vol. iii. pi. 9, f. 5. Lam. vii. p. 78, Perna vulsella, excl. var. b. [Common at St. Vincent and Loander, Tarns. "Omnia plane respondent iis, quae ex Antillis insulis et ex America centrali originem ducunt. = sine dubio, Concha serniaurita, var. Chemn. vol. vii. f. 580. (?f. 579,= P. radiata, Anton Verz. p. 17).] Non O. serniaurita Schroet. loc. cit. f. 6." The Mazatlan shells arc certainly the P. flexuosa of Sow. I cannot detect the slightest specific difference between these, and specimens collected at St. Vincent's (W. I.) by Dr. W. B. Carpenter. These are the P. Chemnitziana of Z>' Orb., which name I have therefore adopted till the date of Sow's is known. Whether it is the shell quoted by DJcr. from Central America and W. I. as well as from Guinea, cannot in so variable a genus be decided only from descriptions and figures. The Mazatlan shells are small, very variable in shape, normally suborbicular, but generally produced. Shell with concentric irregular ridges of growth, but without sculpture on either valve. Beats much produced, terminal ; byssal portion incur- ved ; ventral part flattened. Muscular impression extremely large: ligamental pits deep, numerous and regular. Colour ash, more or less stained with purple, especially at the ventral part, often very rich. The shell in its first appearance seems to be Cyrena-shaped, then like an inflated Anodon, then like Inoceramus, then for some time like a broad Pinna ; then it gradually developes its true form, as far as is consistent with the crevice in which it has taken up its abode. One pit is de- MAZATLAN BIVALVES 151 veloped (as a sinking in the otherwise Avicula-shaped ligament) at a very early stage ; afterwards a second, and so onwards. The prismatic structure is not apparent at first, but soon develops at the ventral portion in cells intermediate in size between those of Avicula sterna and M. Mazatlanica, making the transparent young valves very beautiful objects. The size of the shell when the ligament pits appear, varies greatly ; and the rapidity with w r hich one individual will completely alter its form is most extraordinary. The largest valve measures '03 across ; an enormous specimen, long. 2*1, lat. 1', alt. *5. One of normal shape 1', '7, "24. A produced one 1'53, '51,,, '16. Hob. Cuba, Sagra. St. Vincent's, W. I.. W. B. Carpenter. Conchagua, Hinds. Panama, Lieut. Wood. Mazatlan ; not uncommon in crevices of large shells, affixed by a short strong byssus ; L'pool Col. (Perna a.) Panama ; common under stones and in crevices of rocks at low water mark ; C. B. Adams. La Paz ; Lieut. Green. Tablet 683 contains 7 pairs of valves, extremely young. 684, 4 pairs and 2 pairs of valves, a stage older. 685, 6 pairs and 2 closed hinges, young. 686, 3 pairs adolescent. 687, 4 pairs adult, greatly varying in shape. 688, 2 sp. in situ, in crevices of Patella Mexicana, and in dead Balanus off do. 206. ISOGNOMON JANUS, n. s. I. t. rkomboided, tenui, planatd, pallidd ; valvd inferiori IcBvi, superiori costis gracillimis, interdum obsoletis, testa juni- ore spinis semitubulis imbricatd ; Jiaud auritd, angulo ad umbones acuto ; marginibus ant. et post, subparallelis, subrectis : car dine ligamento ut in Avicula longo,fossibus perpaucis, mini- mis, irregulariter dispositis ; imp. muse, hand magno. Shell known from all the forms of I. Chemnitzii by its regu- lar lozenge shape without ears, thin texture without concentric ridges, light colour, and by the sculpture of the valves of which the under is smooth, the upper ornamented with fine radiating strise, w^hich in the young shell are crowded with semitubular imbricated spines. The hinge Ijne is narrow, without pits when young, when adult with a very few (4) small ones at unequal distances. Muscular impression much smaller than in I. Chemnitzii. The youngest shells are very inseqai- valve, and display capped umbos, consisting of Yenus-shaped 152 MAZATLAN BIVALVES fry. It probably resembles P. costellata, Conr. from the Sandwich Is., but that is described as having both beaks alike. The smallest specimen is '05 in length ; the largest, long, (the diagonal of the lozenge) 1*12, lat. '68, alt. '17. Hob. Mazatlan ; on I. Chemnitzii and Spondylus calcifer, extremely rare : L'pool Col. Tablet 689 contains 1 pair and 2 valves, very young. 690, the most characteristic specimen, in situ. FAMILY GENUS PECTEN, Mull. Of this (in most places) abundant genus only 3 very small valves were found. The neighbouring genus Lima was alto- gether absent. 207. PECTEN CIBCULAEIS, Sow. Proc. Zool. Soc. 1835, p. 110. Hani. Descr. Cat. p. 271. Dull ash, variegated with chocolate ; ears very large ; inter- stices near the umbo finely decussated. The opposite valves differ in sculpture. Long. *28, lat. '26, alt. '12. JZ#6. Guaymas ; in sandy mud, 7 fm. ; Col. Chiming. St. Vincent's [?] Hanley. Mazatlan ; extremely rare : L'pool Col. Tablet 691 contains the only valve I found. FAMILY SPONDYLID^E. GENUS SPONDYLUS, Linn. ~ 208. SPONDYLUS CALCIFEE, n. s. S. t. maxima, ponderosd, solidd, plerumque orbiculari ; rubro- purpureo ; valvd superiors cos t is minimis aculeatis creherrimis tectd, hue et illuc costis irregularibns squamosis ; squamis curtis, ad basim arcuatis, suprafoliatis ; valvd infer- iore plerumque foliates ; area ligamenti magnd, ligament o hand tecto ; intus subnacred, limbo lato toto pur pure o , seu nonnumquam flavesco-rubente ; margine extremo ere- berrime et minute crenulato; dentibus validis ; fossa ligamenti canalibus 2-6 parallelis t decussatis ; musv. imp. sub" orbiculari^ magnd. MAZATLAN BIVALVES 153 Spondylus Lamarckii, Hanley ms. ; et ibi supra, passim : non Sow. Spondylus PLamarckii, C. J9. Ad. Pan. Shells, p. 247, no 385. This species has been quoted in the earlier pages of the foregoing Catalogue under the name of S. Lamarckii. The type of S. Lamarckii, however, is a very different shell, more like S. ducalis, of produced shape, with edges interlocking as in Pecten, and very coarsely crenated in addition : margin dark brownish purple, area not divided, teeth and ligament small. This shell most resembles S. dubius, Brod. Proc. Zool. Soc. 1833, p. 4: = S. pictorum, var. teste Sow. in Thes. Condi. It differs however in the very crowded rows of prickles over the surface ; in the character of the spines, which are arcuated in S. dubius, spreading above in S. calcifer ; and in the interior crenations which are very small in this shell, and scarcely seen in the adult. Mr. Cuming first saw the species, on a small island in the Bay of Panama, where the natives dive for them, to burn into lime ; of which they must furnish an excel- lent supply, being solid, not in chambers as in ' most large Spondyli. He broke up many specimens for their contents, but they were too cumbrous for removal, "some of them being more than a foot high and a foot broad." The adult valves are known at once by the "broad deep red purple finely wrinkled limb of the otherwise white interior," C. 13 . Ad. In its younger stages however, it occasionally displays a salmon colour or even the orange tint of S. dubius. The species was not seen by Mr. Sowerby in preparing his monograph ; but, Mr. J. S. jun.i having directed my attention to many of the above characters, was satisfied of its distinctness. The Mazatlan shells, when young enough to display their characters, are attached by a portion of the lower valve to rocks, large Pinna), &c. The valve develops irregular folia- tions, to aid the adherence. The ligament area is long, rather slanting, and with the groove open to the summit. The upper valve and the unattached portion of the lower are very finely radiately striated, the stria? being granulose, or developing short prickles. At very irrregular intervals, there are very irregular and generally ill-developed ribs, which are here and there armed with vaulted scales, not large even in the young shell. The white, rather nacreous interior displays a broad mar- ginal band, generally purple in the adult, very rarely reddish orange, which is the colour of the young shell. This margin is finely crenated. The muscular scar is very large, irregularly 154 HAZATLAK BIVALVES suborbicular. The ligament has a variable number of longi- tudinal grooves, each broken up into portions like a necklace. The shell is generally suborbicular and massive (sometimes 6 in. thick, JETanl.), and affords a safe asylum not only for the ordinary boring and nestling bivalves, but for numerous small G-asteropods, especially Cceca, Odostomidse, Vitrinellse, Naricse, &c., which establish themselves in empty burrows and in the galleries formed by numerous boring worms, in the coloured portion of the shell. The possession of a single valve therefore is quite a treasure to a patient conchologist ; as, after working out the borers, he will find a plentiful supply of species among the debris. Most of the small shells described in this Catalogue were thus taken from the large Chamae and Spon- dyli, by carefully passing the shell-washings through a fine wire sieve, and examining the remainder under the glass. A single specimen of Spondylus was found to contain the follow- ing species : Parapholas calva, Gastrochsena ovata and trun- cata, Petricola robust a, Rupellaria linguafelis, Saxicava arctica, Sphsenia fragilis, Cumingia 3 sp., Tellina 2 sp., Veiieridse 5 sp., Gouldia Pacifica and varians, Circe margarita, Cardita Cali- fornica, Cardium 2 sp., Lucina, 2 sp., Kellia suborbicularis, Lepton 2 sp., Mytilus 2 sp., Crenella, Septifer, Lithophagus aristatus and plumula, Byssoarca gradata and solida, Chama, Isognomon, Avicula, Anomia, Discina Cumingii, Bullidse 2 sp., Chiton, Patella 2 sp., Siphonaria (2 varieties), Crepidula 2 sp., Fissurella 2 sp., Hipponyx, Vermetus 2 sp., Torinia, Trochus, JN"arica, Vitrinella 6 sp., Fossar, Littorina 2 sp., Rissoidse 5 sp., Jeffreysia, Cerithiadse 5 sp,, Odostomia 6 sp., Chemnitzia 3 sp., Eulima 2 sp., Scalaria, Csecum 5 sp., Columbella 5 sp., Nassa, and Marginella 2 sp : in all 103 species, of which 7 only were fragmentary. It is impossible to say how many more might have been rescued from oblivion, had not the original pur- chaser of the collection immediately sold off almost all the large shells to the keeper of a tea garden connected with a public house near Manchester, where they may be seen, the Pinnae built up into grottos, and the Spondyli and large Patellse arranged alternately round the skirting board of his "Museum." These shells were carefully washed by the publi- can's servant, and the precious dirt thrown away. Mr. Hanley was more fortunate, and obtained many fine specimens from the Havre Col. The largest specimen I obtained measures long. 7', lat.T, alt.6'5. The measurement was however taken after the shell had been decorticated to obtain the borers. MAZATLAN BIVALVES 155 Hob. Bay of Panama, in a few fathoms of water, Cuming ; C. JB. Adams. La Paz ; Lieut. Green. Mazatlan ; not uncommon ; L'pool fy Havre Coll. Tablet 692 contains a young specimen perhaps belonging to this species, but differing from the rest in having the liga- mental groove closed, and the scaly processes larger and more spathulate : long. 2 '3. Tablet 693 contains a very young, [highly coloured valve, '22 across. Tablet 694 contains a young sp. from Pinna, with Ostrese, Vermetidse, &c. attached : long. 4*. Tablet 695 contains a finely grown adult sp., with Verme- tidse, Chama &c. attached. Tablet 696 contains a sp. presented by F. Bacon, Esq., displaying the interior. The outside contains burrows of Parapholas calva, Gastrochsena ovata and truncata, Lithopha- gus aristatus and plumula, &c. Two Pholads remain in situ, having forced themselves against the interior of the shell. Tablet 697 contains a fragment of an attached valve, 2 * 5 in. thick, with numerous burrows, displaying the white marble- like interior portion, and the coloured exterior bored by worms. 698, 2 fragments displaying the colour layers. 699, a fragment exhibiting the orange red colour. 209. ? SPONDYLUS , sp. ind. Tablet 700 contains a fragment with very large flattened tubercular knobs.' Ha b. Mazatlan ; in Chama washings ; L'pool Col. GENUS PLICATULA, Lam. 210. PLICATULA PENICILLATA, n. s. P. t. alba, brunneo scepe tenue penicillatd, elongatd, liaud valde costatd, margine plerumque plicatd ; dentibus cardinali- ties elongatis, rugosis, externis magnis valde extantibus ; internis angustis, lig amentum minimum tubulatum amplectentibus ; cica- trice musculari subcirculari seu subovali. Plicatula dubia, var., Sow. ms. in Mus. Cuming. A small specimen in Mr. Cuming's collection did not present sufficiently marked characters, in the judgment of Mr. Sowerby, 156 MAZATLAN BIVALVES to separate it from the aberrant species from Ld. Hood's Island. The Mazatlan specimens are however distinct both in colour and habit of growth. A very young valve ' 15 across is not plicated : a larger flat specimen on Crepidula is ribbed, but scarcely plaited at the margin : a still larger one is but very indistinctly ribbed. A swollen, short specimen, grown on a spine of Murex nigritus, is rather strongly plicated ; while the largest, in Mr. Darbishire's collection, grown between two folds of Chama, scarcely displays crenations, except near the hinge. The finest grown specimen displays the following characters : margin scarcely plicate, internally finely crenated on each side of the hinge : a deep hollow in each valve running up inside the umbos : central teeth (on the attached valve) joined together for more than half their height, holding the lig- ament, which is extremely small, tubular, only exposed at the extremities, and running up to the umbos, though not exposed (or scarcely covered) as in Spondylus, but nearer the interior of the shell. In the free valve, the ligamental tube rises up, separating the pits of the inner teeth. In this specimen the muscular scar is almost round ; in another, rather oval. The valves are held together by the interlocking of the large rugose teeth. No other species is described from the West American coast. Mr. Darbishire's specimen measures, long. 1*2, lat. *6, alt. "38. Hob. Bay of Fonseca, Cuming. Mazatlan ; extremely rare, on shells ; L'pool Col. Tablet 701 contains the pair off Murex nigritus'; the young flat valve ; and the finest specimen, off Crepidula aculeata, (white var.) FAMILY OSTKEID^E. GENUS OSTEEA, Linn. The usual discriminating marks between species are of little value in this genus. Neither the shape, amount of adherence, sculpture, character of the hinge, colour, direction of the umbos, denticulation or plication of the margin, nor even the shape of the muscular impression, afford unvarying characters. Geographical distribution also is not of much help, the same forms appearing in widely distant seas. The study of the young shells does not, as it is wont, bring fresh light ; very widely separated forms being scarcely distinguishable in early MAZATLAN BIVALVES 157 stages. The prismatic external layer, in rather large cells, is often beautifully apparent at this period. The naturalist has to rely on a balance of characters and the general habit of growth ; and even in these is liable to great error, unless he judge from a comparison of large series of specimens. Those from Mazatlan were numerous enough to confuse, not to help ; and therefore the following descriptions will need verification. 211. OSTEEA IEIDESCENS, Gray. Gray, ms. B. M. Hani. Conch. Misc. Ostrea, pi. 2, f. 6, 7. Ostrea sp. ind. b, C. B. Ad. Pan. Shells, p. 245, no. 381. Compare O. prismatica, Gray, Ann. Phil. vol. xxv. 1825. Comp. O. spathulata, Lain. An. s. Vert. vol. vii. p. 225, no. 16. Comp. jun. O. margaritacea, Lam. loc. cit. p. 228, no. 26. Comp. jun. O. ^Equatorialis, D'Orb. B. M. Cat. Moll. p. 88, no. 776: ? + (teste Gray) O. Puelchana, D'Orb. loc. cit. p. 87, no. 775. Jun. ? = Ostrea rufa (pars), Gould ms. (California.) As it is very doubtful whether the Mazatlan shells belong to either of the imperfectly characterized Lamarckian species, and as they certainly belong to the O. iridescens of Gray, just published by Hanley, I have adopted the latter name. It is recognized pretty distinctly (for an oyster) by its prolonged rectangular shape, long square hinge, laminated not undulated structure, and above all by the brilliant nacre, and rich brown- ish-purple, metallic lustre of the interior. A few flattened knobs appear on each side of the hinge in one valve, fitting into corresponding depressions in the other. Muscular scar large, reniform, variable. This shell has long been known from a large series of very fine African specimens in the Bristol Museum, now, alas, for the most part lost. A valve which came into my possession in the year 1836 contained abundance of Lithophagus aristatus, and 2 valves of Placunanomia per- noides : I believe also that valves of Petricola robusta were out of the same oysters, as there was at that time scarcely a single West Coast shell in that Museum ; but of this I am not certain. On finding the same Oyster and the same Placuna- nomia, along with the same Lithophagus, in the Mazatlan collection, I sought for further confirmation of so singular a fact in geographical distribution. I therefore not only referred to the Bristol Mus. Cat., in which the locality was entered as "West Africa" in Mr. S. Stutchbury's own hand; the em- ployes at the Institution bearing testimony to the same fact ; March 1856. p 158 MAZ.ATLAN BIVALYES but I disentombed the remaining valves, carefully collected the dirt from them, and examined their surfaces. I found 2 perfect specimens of PL pernoides, and many of Lith. aristatus, as well as some red coral on the valves ; and among the dirt 2 (well known African) species of Cardita, 2 of Area, 3 of Odos- tomia, a Chemnitz ia, "Fissurella, Margarita, Purpura and some fragments, none of them occurring on the Mazatlan coast, as well as Kellia suborbicularis, which is supposed to be common to both seas. The locality is further confirmed by the constant trade from Bristol to the Senegambia coast, while there was none (at that time) to West America. Of the specimens in the British Mus., one is from Anamaboa, an island in the W. African seas ; it contains Lith. aristatus, Yermetus glom- eratus, and two young specimens of Placunanomia which ao-ree with PL pernoides in all respects except that the colour is lighter. This is probably from youth and want of light, as I discovered them at the bottom of a Lithophagus burrow, tightly wedged. The other specimen from an unknown locality, (? Australia, G-ray) appears to be from the same seas, from its having the same Lith. aristatus, the same Yermetus, 2 attached valves of the same Placunanomia, as well as a young Hipponyx (not W. Coast Am.), Saxicava ? arctica, and a dead Lucina too imperfect for identification. The Mazatlan shells appear when young to be destitute of denticles. Though normally very distinct from O. Virginica, yet they sometimes approach it in form, developing a very long and waved ligament area, which is then somewhat hol- lowed out inside, though never so much as in O. Yirginica. The smallest valve identified measures * 18 : the largest, (which being from an unknown locality, though probably from Mazat- lan, I have not ventured to include in this collection,) is of regular growth, adherent all over to a very flat surface, and measures long. 9 '25, lat. 6 '3, alt. 2 '07. My African valve which is of more normal shape, measures long. 8*3, lat. 4 '2. A very broad specimen measures long. 4'2, lat. 4*3*. A curiously distorted one measures long 6*5, lat. 2'8 ; of the length almost (when perfect, quite) one half consists of hinge area, in lami- nated chambers ! Hal). Panama ; attached to ledges of rock by the greater part of the lower valve, near half tide level, not common; C. JB. Adams. West Coast America, Hinds. Guacomayo ; on rocks at low water ; Cuming. Mazatlan ; very rare ; L'pool $ Havre Coll.'W. coast Africa ; v. supra. MAZATLAN BIVALVES 159 Tablet 702 contains 4 young valves, side denticles not deve- loped. 703, an adult specimen, normal shape. 704, do. very transverse. 705, do. with very elongated hinge, (from the Havre Col.) kindly presented by S. Hanley, Esq. 212. OSTEEA VIEGINICA, Gmel. Gmel. p. 3336, no. 113, teste Dillw. and WoodDilhv. Descr. Cat. p. 277 Wood. Ind. Test. p. 52, no. 68. Lam. An. s. Vert. vol. vii. p. 225, no. 18. Conr. in Journ. Nat. Sc. Phil. 1829, p. 212, 216. Sow. Gen. f. 2. Ostrea Virginiana, Gmel. teste Lam. loc. cit. et Gould Inv. Mass. Ostrea rostrata maxima, CJiemn. Condi. Cab. vol. viii. p. 38, pi. 73, f. 677. Ostrea elongata, Soland. ms. \-Portl. Cat. p. 55. Sen. = Ostrea crassa, Chemn. loc. cit. p. 40, pi. 74, f. 678. Jun. = Gryphsea angulata, Lam. loc. cit. p. 203, no. 1., teste Sir W. C. Trevelyan in B. M., non auct. + Ostrea Canadensis, Lam. loc. cit. p. 226, no. 19, teste Desk. ? + Ostrea longirostris, Lam. loc. cit. p. 243, no. 17, teste Trevelyan ; sed v. Desk, in loc. ? Ostrea sp. ind. d. C. B. Ad. Pan. Shells, p. 246, no. 383. Jun. ? = Ostrea rufa (pars), Gould, ms. (California.) As the few specimens of this shell sent in the Mazatlan collection do not offer any marks by which they can be distin- guished from the Atlantic O. Virginica, I have followed Mr. Hanley in referring them to that very variable species. So like are they, that I have unfortunately distributed many specimens in Mazatlan collections, received from a trustworthy dealer as from there, which the detection of an entombed Mytilus, known to be a W. Indian and not a Pacific species, has proved to have come from the Atlantic waters, probably from Honduras. These differ from the authenticated Mazatlan specimens in being generally straighter, shorter, thick, with the muscular impression more deeply coloured and lower down : but these characters are not constant in either series. C. B. Adams remarks of his Ostrea d, which usually occurs in clus- ters, that the flavour is superior to that of O. Virginica or O. borealis : but the same may be said on comparing varieties of O. edulis with each other. The O. Virginica is thus described by Gould. " Shell elongated, narrow ; beaks pointed, not much curved ; ligamentary eminence of the upper valve extending back to the apex. This is the common oyster of the Chesapeake 160 MAZATLAN BIVALVES Bay : occasionally found near Boston, and also at Prince ^Ed- ward's Isl., St. Lawrence " : (? = O. Canadensis, Lam*) Conrad (luotes it as fossil in Maryland and as common to the II. States and Europe recent : "Found at Nissan, between Narbonne and Beziers in France, teste Brongniart." A similar shell is in the Br. Mus. from Africa. Another specimen, from the mouth of the Tagus, with a fossil from Lisbon, are marked O. longirostris, Lam. They are considered a var. of O. Yir- ginica by Sir W. C. Trevelyan, who also states that the young is the Gryphgea angulata of Lam. The type specimen of the latter in the Br. Mus, and the young specimens from Mazatlan, appear to me, though not to more experienced naturalists, to confirm this opinion. The species is also from the Portugal Coast in the Bristol Mus. ; and specimens which appear exactly like those from ? Honduras are in the Br. Mus, from China, on the authority of Tradescant Lay, Esq. The form is also from Australia ; Mus. Cuming. The Mazatlan shells when adult are generally rather incurved, thin, with the attached valve convex, foliated, and undulated with very indistinct radiating furrows, which do not appear at all on the flat upper valve. Cartilage area in the lower valve long, deeply undu- lated, generally pointing to the left, sometimes to the right, or straight. Attachment sometimes only to a stick, sometimes to shells by a large part of the surface. When young, sometimes shaped like the adult, sometimes very broad and spreading beyond the inner margin, as though in search of a firm founda- tion for future prolongation. The umbo is then often sub- spiral. In this state it may be generally distinguished from neigl^ouring species by the rich sub-nacreous orange and violet colouring, and absence of crenations near the hinge. Sometimes however it is nearly white, as it generally is when adult. The muscular scar is generally kidney-shaped, but varies in almost every specimen according to the breadth or prolongation. The hinge area is generally hollowed beneath. The youngest identified specimen is '93 long, of which '16 is spiral ligament-area ; another, not so long within, has a straight area measuring '34. The largest specimen in Mr. Darbishire's collection, measures long. 9 '5, lat. 2*1. Sab. Bay of Guayaquil ; in brackish water on mud banks ; Cuming. Mazatlan ; very rare ; Lpool fy Havre Coll. [For localities in other seas, and fossil, v. supraJ] * Lamarck's O. Virginica is characterized by a violet stain on the muscular impression ; but Desh. states that the specimens ticketed in his own hand writ- ing have the impression white, while in his O. Canadensis it is violet. MAZATLAN BIVALVES 161 Tablet 706 contains a young valve, '68 long, and a larger pair, broad spreading form, hinge straight. 707, 1 do. hinge spiral. 708, 3 pairs and a valve, different ages, forms and colours. 709, Area grandis, with valves of O. Virginica at- tached. 710, an adult sp. attached to a twig, with another valve, 4' 5 long, attached to it by its whole length. Another of intermediate size will be found on tablet 20 ; and a valve with Crucibulum. Tablet 711 contains a very small Gryphsea-shaped shell, with spiral umbos, '11 in length, which is probably the young of this species. 213. OSTREA COLUMBIENSIS, Hani. Proc. Zool. Soc. 1845, p. 107 : non Ostrea sp. ind. c, C. B. Ad. Pan. Shells, p. 246, no. 382. Shell inside without denticles, of a pure white, resembling a small O. edulis ; hinge area very small. Outside smooth, or with lamina? of growth ; light ash, with numerous narrow rays of purple. Bather thin, flat, attached by the whole surface. The largest valve (abnormally produced) measures long. 1'55, lat. 1'24. Hob. St. Elena ; adhering to rocks at half- tide ; Cuming. Mazatlan ; on shells and barnacle-covered rocks, very rare ; Upool Col. Lower California, on Area grandis, Gould's Col. Tablet 712 contains a very young pair, detached, and a valve on Imperator unguis. 713, 2 upper valves. 714, 2 pairs, very flat and under valve spreading, probably belonging to this species, though approaching some forms of O. Virginica, jun. 214. OSTKEA CONCHAPHILA, n. S. O. t. plerumque parvd, tenui, subovali, testis variis affixd ; purpured, scepe aurantid tinctd, interdum radiis und vel duabus ; cardine parvo, utroque latere denticulis crenato ; area ligamenti angustd, triangularly scepius sulco denticulato utrdque parte extus ornatd ; plerumque totd valvd affixd, margine integro, sed interdum subiter ascendente, margine undato, vix plicato ; intus subnacreo, cicatrice modico, irregulari. ? = Ostrea Sp. ind. c, C. B. Ad. Pan. Shells, p. 246, no. 382. Shell, when delicately grown among Pinnae and Anomiae, closely resembling O. bicolor, Hani. (Proc. Zool. Soc. 1845, p. 107 : Conch. Misc. pi. 1, f . 2 : supposed to be from West 162 MAZATLAN BIVALVES Africa ;) from which it is known by the minute denticles on each side of the hinge. One T alve, of a rich orange within, has a deep purple streak outside gradually shading off into the most delicate penciling, and another faint ray of clouded purple, leaving two orange areas ; the purple bordering the inner margin, and shading most exquisitely into the orange. Oysters are rarely seen of such surpassing beauty. Ordinarily it is a very small purple shell, frequenting other shells even when living, and often interfering with their growth. It is known by the very small triangular ligament area, with very- fine denticles on each side. In addition to these, there are generally (in the attached valve) two lines of denticles situated in furrows running outside the area to the urnbos. It begins life as a swollen regularly formed body, of the shape of Astarte compressa. A specimen from S. W. Mexico, in a dead Cyprsea, retains this regularity and general form : it is smooth, white, and convex. The hinge of the attached valve, when extremely young, reminds one of Mesodesma ; the ligament being internal between two raised processes followed by pits ; the processes afterwards developing into the ligamental area. Sometimes the shell becomes rather thick, arid, after continuing smooth and flat, suddenly rises, and waves (almost plicating) the outer margin. The young of the stronger shells being brilliant in colour, might easily be taken for those of O. iridescens : if however, (as I have supposed from the valves already quoted) the young of that shell is not crenated, the denticles afford a good distinguishing character ; and, at a later period, the crenated sulei round the area. I have specimens received as from W. Africa, at any rate inhabiting an Atlantic Pinna, which present the same colouring, habit of growth, and some- what remarkable hinge. They seem from the crenations not to be the young of O. bicolor. The finest grown specimen measures long. 1'04, lat. '94, alt. '12. Hob. Mazatlan ; not uncommon, on various shells, v. infra ; L'poolCol.S. W. Mexico, do., P.P. C.? Panama, at- tached to stones, rocks and shells, near half-tide level, C. B. Adams. San Diego, very fine ; Lieut. Green. San. Diego and Oregon ; Nuttall. ? W. Africa, in dead Pinna rudis, P. P. C. Tablet 715 contains 1 pair and 7 valves, extremely young, the smallest "04 across, chiefly from Chamse and Spondyli. 716, a sp. of Anomia lampe, with extremely young oysters in situ. 717, 4 valves, a stage older. 718, a young sp. opened, MAZATLAN BIVALVES 163 orf Anomia lampe, shewing the hinge. 719, 3 valves approach- ing O. iridescens. 720. 3 do. purple, one with the form of Modulus to which it had attached itself. 721, 5 do. orange tinted. 722, 3 do. stronger texture. 723, very young speci- mens on Anomia lampe, with Vermiliae, &c. 724, do. on Cre- pidula and Imperator. 725, a very regular valve on Conus regularis. 726, a pair and valve on living Modulus. The latter must have been greatly in the way of the creature when it walked out : on coming to the extremity of the shell, it has turned up and waved its margin. 727, a very smooth sp. inside Trochus versicolor. 728, 2 finely grown large valves. 729, 2 pairs and valves on Murex nigritus, jun., margin turned up and waved. 730, a pair (and valves) on Area tuberculosa; margin of both upper and lower valve very suddenly turned up and waved. Tablet 731 contains 6 valves, solid white variety, known from O. Columbiensis by the crenations. 732, valve on Vitu- laria salebrosa. 733, crow r ded valves on Area tuberculosa. JN". B. Dead valves, common on this shell, assume an ochre yellow colour. 734, valve on living Modulus, with deep hinge cavity. 214, b. OSTEEA ?? CONCHAPHILA, var. PALMULA. O. ?? conckapkila, t. satis magnd, margine subito ascendente, valvd inferiore superante, undulato, limbo purpureo seu olivaceo irregulariter tessellato ; lined pustularum valvd superiore, in parte naered, a margine remotd, circumeunte, in puncta conveni- entia valvd inferiore aptante ; pagind internd subnacred, auran- tio seu purpureo tinctd ; rarissine spinis ramosis paucis, tubulis ad marginem exteriorem arborescentibus. Compare Ostrea Cumingiana, DJcr. Zeit. f. Mai. 1846, p. 48. (Patria ignota.) Remarkable for the palmated foliations in the outer margin, which has a distinct limb mottled with purple and olive ; and for the row of denticles within this limb and within the nacre- ous border, fitting into corresponding depressions in the other valve. As these seem to appear only in the adult shell, it is barely possible that O. conchaphila may occasionally develop itself into this form. Mr. Nuttall however agrees with me in regarding them as distinct. Long. 2*3, lat. 1*6, alt. '54. Hob. Mazatlan ; extremely rare ; L'pool Col.$. W. Mexico, P. P. (7. Upper California, Nuttall. 164 MAZATLAN BIVALVES Tablet 735 contains a young elongated specimen. 736, another, rounded form, with, a few tubular spines near the mar- gin of the upper valve. 737, the largest sp. with Vermetidse, &c. 215. OSTKEA , sp. ind. ? = Ostrea sp. ind. e, C. B. Ad. Pan. Shells, p. 246, no. 384. Ostrea iridescens, jun. P. P. C. Cat. Prov. Agreeing with O. iridescens in its square form, straight hinge, and nacreous interior ; differing in the irregular radia- tion of the lower valve, and strong sharp plication of the mar- gin. This differs from the undulated margin of O. c. palmula, in not having a distinct limb, with remote line of denticles. These, if present, are very small, and rather near the margin. The characters are so variable that I should have continued to regard this as the young of O. iridescens, but for finding specimens of the latter without hinge denticles, which in these shells are strongly marked ; aAd for the remark of Prof. Adams, with regard to what appears the same species, that the animal has a bitter flavour. Long. 2*5, lat. 2*5, alt. 1'35. Hob. Mazatlan ; very rare, on shells ; Lpool Col. ? Pan- ama ; very common, attached to rocks and stones from one to three-quarters tide level : small var. on Nerita scabri- costa ; C. B. Adams. San Diego, Lieut. Green. Tablet 738 contains 7 very young valves, off Spondyli and Chamse. 739, 1 do. on Imperator olivaceus. 740, 1 do. on Imp. unguis, distorting the shell. 741, 1 young, white valve, resembling O. Virginica, but with crenated hinge. 742, 2 valves approaching O. iridescens. 743, 4 pairs strongly plicate, green within. 744, 1 large pair, attached by portion of the valve to Pinna. FAMILY ANOMIAD^. GENUS PLACUNANOMIA, Brod* Brod. in Proc. Zool. Soc. 1832, p. 29 Gray in B. M. Cat. Anom. p. 8. Subgenus Monia, Gray, Proc. Zool. Soc. 1849, p. 121. 216. PLACCJNANOMIA PEENOIDES, n. s. P. t. forma maxime variante, inter dum transversa, inter dum maxime elongatd, valvd inferiori maxime perf or atd, cuneo intus liris hand tenuibus instructo, fulcro ligamenti valde extante, MAZATLAN BIVALVES 165 spathuloso : valvd superiori muse, cicatr. dualus, quarum una magna, centralis, radiatim tenuissime striata ; alter haudparva, alteri attingens ; lined pallii perdistincta unam alteramque amplectente ; colore atropurpureo, sen atrofusco, subnacreo, splendente ; extus interdum radiatim tenuissime striata; urn- bone a margins subdistante. Comp. Tedinia pernoides, Gray, Proc. Zool. Soc. 1851, p. 197-8. Jun.=Anomia, sp. 3. P. P. C. Cat. Prov. This shell has long been known to me from two attached valves on an African specimen of Ostrea iridescens ; v. supra : but not being aware that it was undescribed, Dr. W. B. Car- penter destroyed one of them for examination into the shell structure. On finding the same species on Chama at Maz- atlan, and comparing it with the t} r pes in the B. M. and Mr. Cuming's Collection, it appeared new, differing from all described species in colour, which is peculiarly dark and lustrous. On the Mazatlan Chama) and Spondyli were found the specimens below enumerated, also a small ovate valve, and a beautiful pair in the collection of Mr. Darbishire. On the African oysters in the British and Bristol Museums I also found specimens as above stated. Mr. Archer has in his col- lection a magnificent upper valve, measuring 2' by 2 '4 in., which he found among the rubbish from a ship laden with pearl oysters from Panama : all the other shells from the same rubbish were known to be from that coast. The Tedinia pernoides of Gray, described from an extremely distorted specimen in Mr. Cuming's Collection, is so very like this shell in its leading characters that I am strongly of opinion that they are identical. Mr. Woodward, who had not felt sufficient confidence in Dr. Gray's genus to admit it into his Manual, examined the shell with me, and we were both doubtful whether the supposed additional muscular scar near the hinge was more than a peculiarity of growth. There were so many lines traceable on the inner surface that a naturalist so disposed might have arranged almost as many muscles as he thought desirable. The point must await the arrival of fresh specimens. To provide for the case of my suspicions being correct, I have given the same specific name to this which is a veritable Placunanomia. The structure of the inner surface of the plug, which is large and coarse, does not appear horny under the microscope ; but composed of parallel shelly plates with much animal matter interlying. The largest Mazatlan specimen 166 MAZATLAN BIVALVES measures long. 1*34, lot. 1*82, alt. *36: an elongated valve from the hole of a Lithodomus, fr ng. 1*52, Za. '6, J?a&, West Coast of Africa on Ostrea iridescens, Stutchbury. Mazatlan ; extremely rare, on Chamse and Spondyli ; L'pool Col. Panama, among pearl oysters ; F. Archer. Tablet 745 contains a young perfect pair, both v alves detach- ed, with hole like Anomia. 746, a broken attached valve, shewing the hinge and portions of the plug. 747, the elongated valve. 748, the largest pair, detached, nearly perfect. 217. PLACUNAUOMIA FOLIATA, Brod. Brod. in Proc. Zool. Soc. 1834, p. Z.Gray in Proc. Zool. Soc. 1849, p. 121 : B. M. Cat. Anom. p. 10. B. M. Cat. D'Orb. Moll. p. 88, no. 778. + P. echinata, Brod. loc. cit., teste Gray. + "P. pectinata, Brod." in Mus. Cuming, teste Gray. Subgenus Pododesmus, Phil., Gray in B. M. Cat. Anom. loc. cit. Only two young and transparent valves were found of this species. White, with central brown stain ; outside with prickly longitudinal strise. They seem to agree with a very characteristic valve found in the S. W. Mexican collection. Long. "75, lat. '57. Hab. Guayaquil Bay ; on dead Pinna in sandy mud, 11 fm. ; Cuming. Ecuador, Guayaquil, D'Orbigny. Isle of Muerte, Broderip. Martinique, no. 6, and Brazils, no. 7 ; Mus. Cum- ing. St. Vincent and Jamaica, Rev. L. Guilding in B. M. S. W. Mexico P. P. C. Mazatlan ; 2 valves in Spondylus calcifer ; L'pool Col. Tablet 749 contains the larger valve and fragments. 218. PLACUNANOMIA CLAVICULATA, n, s. P. t. suborbiculari, tenuissimd, planatd, [l&vi, sen striis in- crementi exillimis : alba, macula brunned disc am candidam pyriformem Jiaud distinctam circumeunte ; valvd inferiori hya- lind, perforatione magnd, fulcliro V -for mi : lamella alba acuta prope perforationem intus decurrente : valvd superiore muse, cicatr. majore subovali, minore rotundatd, modice separata. Subgenus Monia, Gray, loc. cit. Anomia, sp. 2, P. P. C., Cat. Prov. MAZATLAN BIVALVES 167 It is so easy in thin Anomiadse to see the muscular scars one expects, that I had sketched 3 scars for this species to shew the difference in arrangement from those of A. lampe, of which many conchologists had considered my valve a variety. Having however found a pair, and being struck by the V-shaped notch at the cardinal end of the hole, I re-examined the scars, and found the supposed third to be only one of those non-muscular impressions which are very liable to deceive beginners till they have learnt from books what they ought to look for. Shell extremely like Anomia lampe (smooth var.) ; from which it is known at once by the brown disk, inside which is a very faint white disk, with the extremity rounded, not triangular. It is known from P. foliata by the entire absence of radiating striae, which are very conspicuous in young shells of that species. A remarkable feature in this shell is the sharp white lamina, (or clavicle,) which runs from the hinge in the lower valve, near the hole but not parallel with it, losing itself in a thin white deposit in which is the muscular scar. This clavicle, or lengthened support to the cartilage plate, is also seen in P. Cumingii, large, rounded, and running in a straight line to the muscular scar. It is more or less developed in some other species of the genus ; but is remarkable in this for its length, direction and sharpness. Long. 1*12, lat. 1'46, alt. '16. Hob. Mazatlan ; one pair and a valve with Anomise; L'pool Col. Tablet 750 contains the pair. GENUS ANOMIA, Linn. \- 219. ANOMIA LAMPE, Gray. Proc. Zool. Soc. 1849, p. 117 ; B. M. Cat. Anom. p. 19, sp. 14. C. . Ad. Pan. Shells, p. 244, no. 377. This shell in its ordinary state would hardly be known by the meagre description in the B. M. Cat. ; but the very numer- ous finely grown specimens sent in this collection give oppor- tunity to record its leading features. Many hundreds were sent carefully packed ; but most have been broken since they came to this country. There was also a box of valves, many of them extremely brilliant, from which I picked the valve of P. claviculata ; doubtless there were many other treasures in it, but it was unfortunately sold off to make ladies' fancy work before I had an opportunity of examining it. 168 MAZATLAN BIVALVES Shell extremely thin ; lower valve white, smooth ; upper whitish, more or less stained with golden yellow, rarely salmon coloured, extremely rarely greenish, most rarely with a slight touch of pink ; smooth, generally developing irregular radia- ting ribs near the margin, sometimes strong ones all over. Occasionally concentric waves of growth are developed. Lower valve dead white within near the somewhat large (sometimes small) hole, gradually becoming transparent; upper valve with a denned white spathula, somewhat in the shape of an isosceles ^triangle with an excurved base, radiating from the light green ligament, and enclosing the scars. The plug scar is not much larger than the others, and is rounded subquadrate. The others are round, slightly separated, and at a variable angle according to the shape and age of the shell. In different specimens examined, the lines joining the centres of the ter- minal scars with the centre of the middle one, are inclined at angles varying from 105 133 ; shewing how necessary it is to be cautious in founding species merely on the position of the scars. If this divergence of central angle were given in descriptions, it would greatly aid the student. The subcardi- nal scar is small and very slightly impressed. There is a short support from the hinge fulcrum in the lower valve. The plugs, of which a few were fortunately preserved on the outer valves, are very different in appearance from those of A. ephippium ; being large and spreading at the base, but short and small in the attached portion. Extremely fine lines run down the raised part to the margin of the base , but the rest of the base is not grooved. As the shell grows older, it appears to increase the raised part near the umbo, withdrawing from the grooved part of the base, which is no longer covered by the hole. The hole is very much larger than the raised part, which fills only the middle of it. One plug has a large tail, like the expanded foot of a Cyclas, from the gradual shifting of the animal. The raised part has generally a horse-shoe extremity, sometimes built up with very loose shelly matter. The plug under the microscope appears essentially shelly, though with much animal matter. Very young shells are generally orbicular, beginning life as an irregular body without prominent apex, shaped like Discina. The smallest valve is '09 across ; the largest specimen measures long.1'9, lat.2'^, alt. * 14 Hob. California Lady Wigram, B. M. Monterey, 60 fm., Ma- jor Rick. La Paz, do. Panama ; at low water mark ; 1 sp. : C, B. Adams. Mazatlan : common and very fine ; L'pool Col, MAZATLAN BIVALVES Tablet 751 contains 4 valves, extremely young. 752, 6 sp. usual state. 753, 2 do. concentric furrows developed. 754, 6 do. radiating ribs strongly developed. 755, 4 sp. finely grown, ribs slightly developed. 756, 3 do. concentric lines marked. 757, 3 do. almost smooth. 758, 2 do. waxen aspect, like Placunanomia claviculata. Tablet 759 contains 3 sp. bright yellow. 760, 2 do. greenish, ? from Confervse. 761, 2 do. with tinge of pink. Tablet 762 contains 3 sp. salmon tint, radiated. 763, 1 do. with concentric waves. 764, 1 do. with greenish. 765, 1 do. grown over with Vermilise, which indent it throughout. 766, 1 do. square form, with VerrnilisD attached : (a beautiful little species, often found on this and other delicate shells.) 767, 4 lustrous valves, shewing changes in the central angle of scars. Tablet 768 contains 2 sp. distorted growth, inflated 769, 3 do. corrugated surface. 770, 3 do. transverse growth. 771, 2 do. indented. 772, 3 do. right side cut off at various angles. 773, 4 do. left side do. 774, 3 do. vertex, distant from margin. 775, 2 do. hole small. 776, 1 do. with remarkable rows of egg cases. Tablet 777 contains 3 sp. with variously formed plugs attach- ed. 778, a sp. with young attached : both valves are removed, shewing its own plug, and another small one near without corresponding shell. 779, another sp. with young attached ; the upper valve only is removed, shewing the lower in situ. 780, 9 pairs and valves shewing interior. 220. ?- Tablet 781 contains a minute valve, (found since the first part of this Catalogue was printed,) of which it is hard to tell even the generic place. The outside has the general appearance of Sphaenia fragilis ; extremely thin, transparent, covered with a copious epidermis with rather distant concentric layers ; very inequilateral, with an obscure angle from the very projecting umbos to the posterior end. Hinge with two long lamellar teeth, one going posteriorly from the umbo, the other parallel to it, nearer the anterior end. Ligament apparently external, very thin. Long. '05, lat. '027, alt. '007. Hob. Mazatlan ; one fresh valve off Ostrea iridescens ; ISpool CoL March 1856. 170 MAZATLAN UNIVALVES CLASS PTEROPODA. Omnia adJiuc ignota. CLASS GASTEROPODA. The knowledge of this class of Mollusks has rapidly increas- ed since attention has been paid to their mouths and teeth. The main divisions here adopted are probably well founded. In the smaller sections we do not as yet know enough to stereotype an arrangement. Whatever character be taken as the 'guide, families are united, unlike in other respects, or separated when many points of structure indicate affinity. Tht science being in a transition state from the old conch ological arrangements, all dogmatism, on any side, is clearly out of place. SUB-CLASS OPISTHOBBANCHIATA. ORDER TECTIBBANCHIATA. FAMILY CYLICHNID^. GENUS CYLICHJSTA, Loven. 221. CYLICHNA LUTICOLA, C. B. Ad. Bulla (Cylichna) luticola, C. B. Ad. Pan. Shells, p. 215, no. 320: do. p. 319. Haminea luticola, H. fy A. Ad. Gen. vol. ii. p. 16. -Shell remarkably constricted in the middle, swelling an- teriorly. The surface is extremely finely decussated between the well-marked striae of grewth. Long. *1, lat. '04. Hab. Panama ; crawling on liquid mud, near low water mark, at the bottom of a steep sand beach, rare ; C. B. Adams. Mazatlan ; 2 dead specimens off Chama ; L'pool Col. Tablet 782 contains a characteristic specimen. MAZATLAN UNIVALVES 171 GENUS TOBNATINA, A. Adams. Distinguished from Cylichna, Loven, by the head being de- veloped behind into tentacular lobes. Shell with the spire distinct. Columella with a spiral plait. 222. TOENATINA INFEEQUENS, C. B. Ad. Bulla (Tornatina) infrequens, C. B. Ad. Pan. Shells, p. 214, no. 319 ; do. p. 319. P= Bulla (Tornatina) gracilis, Mke. (non A. Ad.} Zeit.f. Mai. 1850, p. 162, no. 3. Menke's species being white, not horn-coloured like T. gra- cilis from the China Seas, and being identified from a single specimen wedged in the mouth of a dead Conus puncticulatus, is almost certainly the same as that described by C. IB. Ad. from Panama. T. infrequens is distinguished by the Oliva- like spire, more or less elevated and deeply channeled along the suture. The body whirl is not swollen anteriorly, and the fold lies slanting on its base. Long. '14, long. spir. '03. lat. '05, Sab. Panama ; extremely rare ; C. B. Adams. Mazatlan ; very rare, on Spondylus calcifer ; L'pool Col. Tablet 783 contains the finest specimen ; and the smallest measuring, ' 07 in length. ^ 223. TOENATINA CAEINATA, n. s. T. t. cylindraced, alba, lavi, infra suturam appressam acute carinatd ; inter suturam et carinam excavatd ; anfr. v. guarum duo primi discoidales, ad spiram verticaliter affixi ; spird plus minusve extante ; aperturd prcelongd, labro acuto, in medio producto, postice ad suturam vix canaliculato ; labro tenui ; pariete ad basin tumidd ; columelld plied infra parietem robustd spiraliter munitd. Known from T. infrequens (1) by the smaller size, and more irregular spire ; (2) by the suture, which is not channeled ; (3) by the shoulder, which is sharply carinated, with the space hollowed between the keel and suture ; (4) by the swelling of the body whirl at the base ; and (5) by the plait which runs more transversely, below the body whirl, instead of obliquely, almost on it, as in T. infrequens. By some of the above char- acters it is further distinguished from T. cerealis, G-ld. (Mex. fy 172 MAZATLAN UNIVALVES Cal. Shells, p. 5, Sta Barbara, Jewett,) which resembles T. infrequens much more closely than this species. All the three forms begin life as a small discoidal body, like a tumid Planor- bis. After making about two turns of this, they proceed in the regular way, affixing the disk vertically, or sometimes in a slanting direction, at the top of the spire. The length of spire in this species, which is not so rare as T. infrequens, is extremely variable. The smallest specimen is '037 long. The largest measures long. 11, long. spir. "02, lot. '05. The discoidal apex is '005 across. Sab. Mazatlan ; on Chama and Spondylus, very rare ; Jj'pool Col. Tablet 784 contains 5 sp. varying in age and shape, and a fragment to shew the apex. FAMILY BULLID^E. GENUS BULLA, Klein. 4" 224. BULLA ADAMSI, Mice. Zeit.f. Mai. 1850, p. 162, no. 1. (syn. excl.) Dr. Menke regards this shell as that figured in Sow. TJies. Conch, f. 64, 65, under the name of B. australis. In this he is probably mistaken, but not in regarding the species as distinct both from that and from B. Panamensis, Phil. It greatly resembles B. media, Phil, and still more B. major, Phil., both from the West Indies. It differs from the Upper Calif ornian B. nebulosa, when adult, in being much smaller, more solid and contracted, and in having a much larger umbilicus. Shell chocolate coloured, very variously dotted with white, shadowed off in dark. Lip at the base strongly reflected, in the young shell distinct from the labium, which is well marked, white. Apex deeply umbilicate, shewing the whirls and with the inside spirally striated. The whole surface (described by Menke as smooth) is covered with extremely fine spiral microscopic striae, irregular, sometimes broken into dots by the striae of growth. Epidermis horny, thin. Long. 1*38, lat. '91. Sab. Mazatlan, Menke. Do. : not common ; L'pool Col. Tablet 785 contains 3 specimens approaching B. nebulosa in texture. 786, 2 do. normal form. 787, 2 do. more tumid, strong. MAZATLAN UNIVALVES 173 225. BULLA ? NEBULOSA, Gould. U. 8. Expl Exp. Moll.MJce. in Zeii. f. Hal 1850, p. 162, no. 2. A very few thin, subglobose shells were found, with a small umbilicus, which are undistinguishable from the young of B. nebulosa ; a species which, along with other points of simil- arity, shews the spirally striate umbilicus, and traces (though faint) of the rugosely striulate surface, of B. Adamsi. B. nebulosa is quoted from Guaymas, and may be one of the very few Californian species which cross the Gulf. I strongly sus- pect however that these are but aberrant forms of the young B. Adamsi ; which varies not a little in outline, solidity, and size of umbilicus. The adult shells are sufficiently distinct. Long. 1', lat. '7. Hob. Sta. Barbara, Nuttall. San Diego, Lieut. Green. Guaymas ; in sand, 12 in.; Mus.Cuming. Mazatlan ; Menke. ?Do. jun. extremely rare ; Lpool Col. Tablet 788 contains the most characteristic specimen. 226. BULLA ? QUOYII, Gray. Sow. Thes. Conck. sp. 48, pi. 173, f. 71. A very few small specimens were found, differing from B. Adamsi in the following points. Surface much more strongly and closely striulate ; outline flattened towards the umbilicus, at an angle of about 60. Umbilicus strongly striate, bounded by a blunt angle. Long. '5, lat. *3. Hob. Gallapagos, Cuming. ? Mazatlan ; extremely rare ; L'pool Col. Tablet 789 contains 3 minute sp., probably belonging to this species. 790, the ? adult specimen. 227. BULLA EXAEATA, n. s. B. t. parvd, ellipticd, compressd, aperturd elongatd, angustd ; fused, epidermide tenui cincta ; spiraliter tenuissime exaratd, lineis plus minusve distantibus, in medio plerumque evanidis ; spird haud alte umbilicatd, intus striulis transversis divaric&ta ; labro postice producto ; labio columellam versus rimulam ^l>mb^- licalem simulanie. Distinguished by the acuminated form, fine, rather distant spiral grooves, narrow produced aperture, and slight umbilical chink formed by a fold of the labium. The small spiral umbili- 174 MAZATLAN UNIVALVES cus appears sliglitly denticulate within, from the striae of growth being there well marked. The labrum extends '005 beyond the spire. Long. '125, lat. '055. JIab. Mazatlan ; 2 sp. on Spondylus calcifer ; Lpool Col. Tablet 791 contains the larger specimen, slightly imperfect. 228. BULLA , sp. ind. Tablet 792 contains a small fragment, remarkable for the sharp angle round the spiral umbilicus. This is furnished within with spiral grooves so strongly marked as to cause the produced labrum to be serrated on the outer side at its junc- tion with the body whirl. Hab. Mazatlan ; on Spondylus calcifer ; Lpool Col. GENUS HAMIKEA, Leach. Bulla (pars) auct. Shell horny, elastic, colourless, semi-interna. 229. HAMINEA CYMBIFOEMIS, n. s. H. t. tenuissimd, albidd, axi contort a, maxime inflatd, spird minore, celatd ; aperturd antice ventricosd, postice productd ; striulis spiralibus creberrimis ornatd, rugis incrementi subex- tantibus ; labio tenuissimo. Only one rather imperfect specimen was found of this beautiful species, which resembles in form a small inflated Cymbium. Long. '07, lat. '05. Hab. Mazatlan ; 1 sp. on Spondylus calcifer ; Lpool Col. Tablet 793 contains the specimen. SUB-CLASS PTJLMONATA. OEDEE GEOPHILA. FAMILY TESTACELLIILE. Gray in S. M. Cat. Pulm. p. 9. GENUS GLANDINA, Sckum. Essai Syst. p. 202, 1817. Oleacina, Bolten, Mus. (1798) ; ed. 2, 1819, p. 77. Cochlicopa a, Ferus. Tab. Syst. 1821. Achatina, pars, auct. MAZATLAN UNIVALVES 175 Dr. Gray unites Oleacina, Glaiidina and Halia under the former name, (B. M. Cat. Pulm. p. 13 ;) H & A. Adams con- sider them distinct : Gen. vol. ii. p. 107. Ordinary students have no power of ascertaining whether generic names given with an early date are accompanied by a diagnosis, and there- fore of authority, or whether they are only names which have been attached to certain species, and not entitled to take pre- cedence of a regularly defined genus. The animal of Glandina is said to be carnivorous, and to resemble Testacellas with the spiral part developed. 230. GLANDINA ALBEESI, Pfr. Achatina Albersi (Glandina) Pferf. in Proc. Zool. Soc. 1854, p. 295. A very few specimens of this unpretending species were found among the Physae. It appears to take the place of G. rosea, found lower down the peninsula. The shape is extremely variable, being sometimes elongated like G. turris ; sometimes very much swollen, with a short spire. A turreted specimen measures . . . long. 1*2, long. spir. '59, lot. '5. A swollen sp. . . 1', ,, '42, .5. Sab. Mazatlan ; extremely rare ; L'pool Col. Tablet 794 contains 3 sp. : one turreted, one swollen, one curiously mended after fracture. 231. GLANDINA TUEEIS, Pfr. Achatina turris (Glandina) Pfr. Symb. iii. p. 91, no. 126 : Hon. Helic. ii. 28S.Rve. Conch. Ic. pi. 13, f. 45. Desk. I. c. 186, no. 51, pi. 134, f. 1, 2B. M. Cat. Pulm. pt. i. p. 25, no. 29. =G. Albersi, var. turrita, P. P. C., Cat. Prov. Acicula turris, H. fy A. Ad. Gen. vol. ii. p. 109. This species is kept separate provisionally on the authority of Dr. Pfeiffer. As only one specimen was found in the Maz- atlan collection, it would not be fair to decide without further evidence. It appears to differ from the elongated var. of G. Albersi, simply in the still greater elongation, greater arcuation of the columella, and greater fineness of the striae. But all these characters are variable in the other species. Long. 1'2; long. spir. '61, lat. '48. Sab. Mexico, Liebmann. Mazatlan ; 1 sp. among Physae ; L'pool Col. Tablet 795 contains the specimen. 176 MAZATLAN UNIVALVES FAMILY HELICID^E. GENUS OKTHALICUS, Beck. H. fy A. Ad. Gen. vol. ii. p. 154. The animal differs from that of Bnlimus proper, according to Troschel in Zeit. f. Mai. 1847, p. 50, (note.) Bnlimus, pars, auct. 232. OETHALICUS ZEBEA, Mull. Buccinum zebra, Mull. Verm. p. 138, no. 331. List. Conch. pi. 580, f. 34 Fav. Conch, pi. 65, f. M. 2Seba, Mus. 3, t. 39, f. 54, tt.Gualt. Ind. pi. 5, f. N. (Zebra Miilleri,) Chemn. Conch, vol. ix. pt. 2, p. 24, pi. 118, f. 1015-6. Ram- merer, Cab. rud. pi. 80, f. 4. Bnlla zebra, Gmel. p. 3431, no. 31. Schroet. Flussconch. p. 325, pi. min. A, f. 4, + no. Y^-.Einl. vol. ii. p. 216, no. 143. Dillw. Descr. Cat. vol. i. p. 494, no. 52. Bulimus zebra, Desh. in Lam. An. s. Vert. vol. viii. p. 223. Anton Verz. p. 43, no. 1577. DOrb. Moll. Cub. vol. i. p. 174, pi. 6, f. 9, lO.Pfr. St/mb. no. 372. MJce. in Zeit. f. Mai. 1850, p. 163, no. 4. Achatma zebra, Pfr. Symb. ii. p. 135 : non Chemn. nee Lam. Kammerer, p. 126, pi. 10, f- 4. Orthalicus undatus et zebra, Beck. Ind. p. 59, no. 5, 6. Orthalicns zebra, S. fy A. Ad. Gen. vol. ii. p. 154, pi. 75, f. 6, 6 a. Helix nndata, Daudeb. Hist, des Moll. pi. 114, f. 5, 8 ; pi. 115. Wagn. in Spix. Test. Braz. p. 9, no. 12, pi. 9, f. 2. Moric. Mem. de Geneve, vol. vii. pt. 2, p. 423, no. 14. (? JN"on H. undata, Dillw. p. 958.) Helix (Cochlostyla) nndata, Fer. Hist. p. 337, pi. 114, f. 58, pi. 115, f. 1 6. DOrb. Synops. p. 8. Bnlimns undatus, Brug. Diet. no. 38 :Enc< Meth. p. 320, no. 38. Lam. loc. cit. no. 5. Valenc. in Humb. Zool. vol. ii. p. 245, pi. 55, f. \.-Kust. Bui. p. 6, pi. 2, f. 4, 5 . B. M. Cat. D'Orb. Moll. p. 13, no. 134 -.Cuba Moll. p. 10, no. 93. Var. = Bnlimns melanocheilns, Val. in Humb. Zool. vol. ii. p. 246, pi. 55, f. 3. Var. = Orthalicns livens, Beck. Ind. p. 59, no. 7. + Bulimns zigzag, Lam. loc. cit. no. 4, teste Desh. + Bulimus princeps, Brod. Proc. Zool. Soc. 1832 -.Sow. Conch. 111. f. 18. MAZATLAN UNIVALVES 177 Helix (Cochlostyla) princeps, D'Orb. Synops. p. 8. Orthalicus princeps, Beck. Ind. p. 59, no. 3. Achatina pulchella, Spix. This well known and widely distributed species is the only land shell which appears at all common at Mazatlan. It varies greatly in pattern, as will be seen by the following list. Most of the shells were young, but characteristic. The first 3 or 4 whirls rarely display any painting. Long. 2'1, lat. I'l. Hob. Brazils, Peru, Columbia, D'Orbigny. Cuba, Sagra. Conchagua, Broderip. Mazatlan ; common ; L'pool Col. Tablet 796 contains 5 sp., with very large dark patches. 797, 4 do. patches diagonal. 798, 3 do. patches smaller. 799, 1 do. patches clouded. 800, 5 do. gathering into knots. 801, 7 do. normal painting, knotted in spiral bands. 802, 4 do. very fine, scarcely zigzag stripes. 803, 3 do. irregularly crowded. 804, 4 do. knotted pattern extremely faint. 805, 3 do. yellow- ish, with spiral brown lines at the base. 806, 1 sp. yellowish, without pattern. 807, 5 sp. elongated form. 808, 1 sp. with winter epiphragm. 809, 3 sp. broken and mended by the animal. 233. ORTHALICUS ZiEaLEKi, Pfr. Bulimus Ziegleri, Pfr. Proc. Zool. Soc. 1846, p. 113, no. 25 : Symb. no. 472. Leiostracus Ziegleri, H. <$f A. Ad. Gen. vol. ii. p. 151. This shell is placed by Messrs. Adams in a subgenus of Otostomus. It has however a sharp, non-reflected lip ; as well as a very small, scarcely covered umbilicus. A very few speci- mens were found with the Physse. An unusually large one, in which the linear patches of colour are almost evanescent, measures long. '69, long. spir. '35, lat. '34. Hob. Central America, Largilliert. Mexico, Liebmann. Mazatlan ; extremely rare ; L'pool Col. Tablet 810 contains 2 sp., one of normal colouring, the other the pale variety. 234. OETHALICUS ? MEXICANUS, Lam. Bulimus Mexicanus, Lam. An. s. Vert. vol. viii. p, 232, no. 23. Vol. in Humb. Hec. Zool. Leiostracus Mexicanus, If. Sf A. Ad. Gen. ii. 150. = Helix vittata, Daud. Hist. Moll. no. 397. 178 MAZATLAN UXIYALVES Tablet 811 contains a sketch of a solitary specimen which was found by Mr. Archer amoag the small shells. It was referred by Mr. Cuming to Bulinus Broderipii, Sow. in Proc. Zool. Soc. 1832: Conck. III. f. 1. ( = Plectostylus Broderipii, H. fy A. Ad. Gen. ii. 155 :) but as it does not accord with the figures of that Chilian species, it was perhaps an oversight. Lamarck's description might also serve for B. Ziegleri, which this shell very greatly resembles. It is however more inflated and thinner. Long. '65, long. spir. '35, lat. *4. Hob. Mexico, Humboldt fy Bonpland- ? Mazatlan ; 1 sp. with B. Ziegleri ; L'pool Col. OEDEE LIMNOPHILA. FAMILY AUBICULIDyE. GENUS MELAMPUS, Montf. Melampus, Montf. Conck. Syst. 1810. Conovulus, Lam. 1812. This genus was afterwards suppressed by its author, and united to Auricula. 4 235. MELAMPUS OLIVACEUS, n. s. M. t. parvd, sublcevi, conoided, spird depressd, infra suturam indistinctam obscure angulatd ; albidd, fusco-purpureo irregu- lariter tessellatd, epidermide adkcerente olivaced indutd ; anfr. vii. vix rnonstrantibus, planatis ; aperturd longd, angustd, ad marginemfusco-purpured, intus albd ; labro ad marginem acuto, intus dentato, dentibus in liras acutas, in adultd scepe obsoletas, decurrentibus ; labio tenui, plied und parietali transversd, inter denticulas duas sitd, in juniore denticulis mynerosis intus conditis ; columelld plied und obliqud, ad basin excurrente ; parietibus internis in adultd absorptis. Melampus bidentatus, Moerch in Mus. Cum. : non Say. Moerch must surely have been in error in regarding this species as a variety of M. bidentatus. It is much more nearly allied to the Yoluta cofiea of Linn. The specimens, of which many hundreds were sent, are very constant in the characters above given ; of which the most distinguishing are the olive green epidermis, with the irregular purplish brown tessellated MAZATLAN UNIVALVES 179 patches often shewing through ; the sharp purplish outer lip, well armed with white ridges within, in the young shell, which afterwards develope strong teeth at the ends, and are last of all absorbed ; and the thin inner lip, which developes one strong transverse parietal plate between two small denticles (others being just discernable in the young shell), and one large slanting columellar fold, which winds round the base of the pillar, making an umbilical chink. A few extremely faint spiral striae are sometimes seen on the epidermis, near the base and above the bluntly angled shoulder. Long. '65, long. spir. "11, lot. '38, mean div. 110. Hab. Mazatlan, Lieut. Shipley, Do. ; not uncommon; L'pool Col. Tablet 812 contains 9 sp. normal state. 813, 4 do. dark variety. 814, 4 do. light var. FAMILY LIMNEID^E. GEN-US APLEXA, Flem. Hist. Er. An. 1828, p. 276. Gray, Proc. Zool. Soc. 1847, p. 180 : do. Turt. ed. ii. Beck in Phil. Handl. Conch. p. 255. Bulinus, Adanson, teste Gray Fig. Moll. An. 1850, p. 119. H. fy A. Ad. Gen. vol. ii. p. 259. JSTon Bulinus, Adanson, teste Gray, Proc. Zool. Soc. 1847, p. 180, nee Seek in Phil. Sandb. Conch, p. 255 : nee Bulinus, Soio. Physa, pars, auct. Mantle simple edged. The shells of this section indicate affinity with the A. hypnorum, the animal of which is sufficiently distinct from the typical Physee. The species in this genus are extremely difficult to distinguish, especially in the young state. The naturalist has to rely principally on the general habit, individual characters being subject to variation. J 236. APLEXA AUEANTIA, n. s. A. t. tenui, ovatd, Icevigatd seu striis incrementi exillimis, nitidd, aurantio-corned, ad spiramfuscd ; spirdparvd, in adult a semper erosa; anfr. circiter vii., subplanatis, twmidis ; aperturd satis dilatatd ; labio tenuissimo arcuato ; columella vix plicatd. Physa Peruviana, Wee. in Zeit.f. Hal. 1850, p. 163, no. 6 : P. P. C. Cat. Prov. : non Gray, Spic. Zool. p. 5, pi. 6, f. 10. 180 MAZATLAN UNIVALVES This fine species, which, is generally named P. Peruviana in collections, is quite distinct from the types in the Br. Mus. It much more nearly approaches A. Maugerse, which is believed to be a Caribbean species, (not Californian, as stated by Wbodw. Man. ii. 171.) It differs in shape, which is never so elongated, and in colour which is almost always orange horn, with a tendency to darker shades, in rays, below the suture. Shell swollen, thin, glossy, with an extremely thin columellar lip, projecting beyond the aperture, and indented at the base of the body whirl. The length of the spire varies in different specimens, as does also the amount of convexity. The true A. Peruviana has a very prominent apex, with shouldered, swollen body whirl. Allowance must be made in the following measurements for the constant erosion of the apex. A slender specimen measures long. 1'23, long. spir. '27, lat. '63. A swollen sp. 1*25, "24, '7. The largest specimen must have measured 1*43 : mean div. 60^. Sab. Mazatlan ; not common : L'pool Col. Tablet 815 contains 5 sp. slender. 816, 5 do. swollen. 817, 5 do. normal state. 818, 5 do. dark variety, approaching A. Maugerse in texture. 819, 2 sp. of distorted growth. 4- 237. APLEXA ELATA, Gould. Physa e., Gould Col. fy Mex. Shells, p. 6, pi. 14, f. 4. It is almost impossible to draw the line between this species and the young of A. aurantia. Nevertheless, as a vast number of this shell were sent, and very few of the other, it is presumed that it is adult. It differs considerably from the adult form of A. aurantia, being very much smaller, thinner, more, pointed, of a light horn colour, with the whirls extremely smooth, and the apex never eroded. In shape it is more like A. Maugerse. Exactly at the suture there is generally an ill-defined line of lighter colour with one of darker colour below. It varies somewhat, like the last species, in the comparative length of the spire. An unusually large specimen measures long. 1'08, long. spir. '28, lat. *5, mean div. 50. Hob. Lower California, Major Rich. Mazatlan ; very com- mon ; L'pool Col. Tablet 820 contains 10 sp. normal state. 821, 6 do. more swollen. 822, 9 do. colour approaching A. aurantia. 823, a distorted sp. slightly angled at the suture. MAZATLAN UNIVALVES 181 GENUS PLAJSTORBIS, Guettard. j^ 238. PLANORBIS TUMENS, n. s. P. t. rapide tumente, parvd, corned seu rufo-fuscd ; anfracti- bus iv.-v., concentrice tenue striatis, striis undulatis ; suturis valde impressis ; latere altero prope suturam subangulato, seu inter dum subcarinato ; altero rotundato ; umbilico altissimo ; aperturd margine sinuato, latere altero supra extante, infra compressd, altero supra planatd, infra productd, capad, rotun- datd ; labio tenuissimo. Planorbis affinis, P. P. C. Cat. Prov. ; non C. S. Ad. in Contr. Conch, no. 3. p. 44. Planorbis tenagophilus, Mke. Zeil.f. Mai. 1850, p. 163, no. 5 : non D'Orb., S. M. Cat. Moll p. 25, no. 234. This species is so variable that it is difficult to describe it so as to include all the specimens and yet separate it from its congeners. Aberrant individuals on the one side closely approach P. affinis, on the other P. lentus, Say. The three may hereafter be proved identical : but the general habit of P. tumens, as gathered [from repeated examinations of many hundred specimens, is sufficiently distinct from the Jamaica species. The whirls are more rapidly enlarging, more swollen, and the lip more shouldered. An unusually large specimen measures long. *63, lat. "58, alt. '27. Sab. Mazatlan ; not uncommon ; L'pool Col. Tablet 824 contains 3 sp., deep narrow umbilicus. 825, 5 do. ordinary state. 826, 4 do. umbilical suture large 827, 4 do. umbilicus flattened. 828, 3 do. base rounded. Tablet 829 contains 3 sp. reddish brown var., spreading. 830, 3 do. ordinary state. 831, 3 do. keeled. Tablet 832 contains 7 sp. distorted growth. OBDER THALASSOPHILA. FAMILY SIPHONAEIAD^E. GENUS SIPHONAEIA, Gray. Gray in Sow. Gen. part xxi. 1824. Blainv. Diet. Sc. Nat. vol. xxxii. p. 267. Mouretia, (Gray) Sow. 1835. Trimusculus, Schmidt, 1832. April 1856. r 182 MAZATLAN UNIVALVES This remarkable genus does not appear to be rich in species at Mazatlan. The magnificent S. gigas (? + char act eristica), though traveling as far north as S. W. Mexico, where it is not uncommon - (P. P. C.) y was entirely absent (adult) from this collection. 239. SIPHONAEIA LECANIUM, Phil. S. t. parvd, plerumque ovatd, interdum subdrculari^ ad cana- lem projiciente ; subconwd, sen valde depressd ; cinered, fusca, var'ie pictd ; epidermide tenui, adharente ; costis . Mazatlan, Philippi ; do. Melchers.; do. abundant ; L'pool Col. Tablet 833 contains the youngest .specimen, Navicella-shaped, and an older one with the scar from the detached spiral part. 834, 8 sp. jun. different ages, with spiral part visible. 835, 9 sp. do. spiral part detached. Tablet 836 contains 3 sp. var. palmata, very few (11 + ) ribs. 837, 4 do. large and regular. 838, 5 do. irregular. 839, 4 do. ribs very numerous, (22,) smaller. 840, 4 do. interstices of palmations slightly crenate. 841, 5 do. interstices crenated. 842, 4 do. greenish tinge. 843, 5 do. light brown. 844, 4 do. very dark. 845, 3 do. nearly black. Intermediate form ; slightly palmated margin. Tablet 846 contains 3 sp. approaching var. palmata. 847, 3 do. dark brown. 848, 3 do. white margin. 849, 3 do.. light brown, 850, 2 do. chocolate colour. 184 MAZATLAN UN T VALVES Ordinary state. Tablet 851 contains 3 sp. light brown. 852, 4 do. darker. 853, 4 do. whitish margin. 854, 4 do. broad white margin. 855, 4 sp. blackish brown, white margin. 856, 4 do. penciled. 857, 4 do. tessellated. 858, 4 do. nearly black. Specimens shewing exterior. 859, 3 sp. fine growth, with epidermis. 860, 4 do. principal ribs few. 86J, 5 do. more numerous. 862, 5 do. principal ribs scarcely developed. 863, 1 do. with very fine crowded riblets, here and there developing into principal ribs. 864, 2 sp. very conical. Tablet 865 contains 4 sp. probably belonging to this species, but approaching S. aequilirata. Principal ribs scarcely traceable. 240. SlPHONAKIA ^QUILIKATA, n. S. S. t. subconicd, ovali, regulari, liris numerosis subrugulosis, fequalibus, radiatim ornatd, interstitiis haud latis, Icevibus ; fusco-olivaced, liris altis ; epidermide tenui, adh&rente ; pagind internd fused, vix iridescente ; margine crenulato ; canali sub- centrali, extus haud prominent l e. One specimen of beautiful growth in the Mazatlan collection agrees with a larger but somewhat irregular one in that of Mr. Cuming, in characters which appear to separate it from all varieties of S. Lecanium. Eiblets equal, interstices smooth, channel nearer the middle and not conspicuous either by swelling or special marking outside. The Mazatlan specimen has much broader interstices than that of Mr. Cuming ; but as the riblets are bifurcating, it is probably not fully grown. There is no trace of striulse. The examination of more speci- mens may possibly merge it into the polymorphous S. Lecanium, from the extreme variety of which the non-prominence of the canal appears to separate it. Mr. Cuming's specimen measures long. '83, lat. '57, alt. '3. Hob. Gulf of California, Lieut. Shipley. Mazatlan ; 1 sp. only ; L'pool Col. Tablet 866 contains the specimen. 241. SIPHON AEI A sp. ind. Tablet 867 contains a very young specimen, * 07 by "05, of Navicella shape, with a large spiral apex, extremely thin, and evidently belonging to a very much larger species than S. Lecanium, possibly to S. gigas. Hab Mazatlan ; 1 sp. in shell washings ; L'pool Col. MAZATLAN UNIVALVES 185 SUBCLASS PEOSOBEANCHIATA. In those families in which the first whirls are abnormal as compared with the rest, as compared with the rest, these are called the nucleus, although they may be more than the part so formed in the egg, and their first whirl the apex. The measurements marked div. represent the mean divergence of the outlines of the spire. OEDER HETEEOPODA. FAMILY IANTHIJNTD.E. This aberrant group is ranked with Carinaria in the Subclass Heteropoda by H. fy A. Adams, Gen. vol. ii. p. 85 ; between Scalaridse and Stylinidse by PJiilippi, Handb. Conch, p. 179 ; next to Ampullariadse, Gray, 1847 ; with the Heteropoda in Order Pleurobranchiata, Gray 1850 ; between Neritopsidse and Scalariadae, in the Suborder Proboscidifera, Gray, 1855 ; next to Trochidse, Forbes fy Hani. Br. Moll. vol. ii. p. 547 ; in the Family Haliotidse, Wbodw. Man. pt. 1, p. 148., It has affinities in all these groups. The vertex is not sinistral as in Pyramidellidse ; but dextral, fixed slanting from the future axis of the shell. GENUS IANTHINA, Lam. It is necessary that more materials should be collected, and the animals observed, before a decided opinion can be expressed on the species of this genus. Some would reduce most of the forms to one or two species, Dr. Gray even hazarding the conjecture that the two forms usually found together (I. fra- gilis and I. prolongata) are the sexes of one species, (J3. M. Cat. D'Orb. Moll. p. 35.) Mr. M'Andrew however found them in the Canaries separate, and miles apart. Others will believe that many different species have been confounded. In the ab- sence of information respecting the animals, it has been thought best to describe the Pacific species as distinct ; although it is highly probable that they may hereafter be identified with those from the W. Indies. The smaller Atlantic form is repre- sented, in the Pacific waters, by the beautiful I. bifida, Nutt. from the Sandwich Islands. J- 242. IANTHINA STEIULATA, nom.prov. I. t. "I.fragili" simillima ; nucleo haud valde oblique sito, anfractibus iv., globose, apice planato, suturis nullis ; anfracti- 186 MAZATLAN UNIVALVES bus primis lirulis concentricis acutis pulcherrime instructis, postea lineas incrementi monstra Mbus ; lineis spiralibus plus minusve distinctis ; angulo mediano distineto ; superne pallidis- simd, inferne violascente ; columelld tenuissimd, plica 'acutd instruct d, ad basim plus minusve extort d ; labro plus minusve sinuato, sinu angulato ; labio vix projiciente, tenuissimo. Comp. lanthina fragilis, D'Orb., B. M. Cat. Cuba Moll. p. 23, no. 258 : B. M. Cat. D'Orb. Moll. p. 36, no* 316 : B. M. Cat. Can. Moll. p. 15, no. 107 : ( = 1. communis, Lam. An. s. Vert. vol. ix. p. 4, pars.) This shell may hereafter prove to be identical with one of the various Atlantic species. There are two forms called I. fragilis from the W. Indies ; one agreeing with this in the separation of colours and sharp columella, but with more pink in the violet tinge ; the other agreeing in tint, but with the colour diffused and the columella coarser. All differ essentially from the British I. communis, (of which there are two very different ? varieties) in the very fine concentric liration of the upper whirls, and in the character of the nucleus. This, in I. communis, is sunken, but not flattened at the apex ; in the tropical species it is rather prominent, but flattened at the top. It is not so horny as in the next species, and is always persis- tent. The shape is tolerably constant ; but the amount of sinuation in the outer lip somewhat varies. The very young snell is globular, without angular keel. Long. '78, long. spir. '44, lat. I', di jffab. Mazatlan ; abundant ; L'pool Col. Tablet 868 contains a very young sp. '04 across, broken, but shewing the transition between the oblique and straight por- tions-. r869, a young sp. with fry adhering to the suture. 870, 3 sp. depressed form. 871, 5 sp. normal state, jun. 872, 5 do. adult. 873, 4 sp. spire elevated. 874, 3 sp. basal angle pro- duced. 875, 4 do. shoulder curiously swollen. 876, 7 do. broken and mended by the animal. 242, b. IANTHINA STEIULATA, var. CONTOBTA. I. ?striulata, columelld maxime contortd, ad basim productd, reflexd, sinu may no, haud angulato. This shell when taken alone would certainly be regarded as a distinct species : but as several specimens of I. striulata shew MAZATLAN UNIVALVES 187 somewhat of an approach to it, it is presumed (in the absence of knowledge of the animal) to be an aberrant variety. Hob. Mazatlan ; extremely rare ; ISpool Col. Tablet 877 contains the extreme specimen, and a younger one, intermediate. The larger sp. is but slightly waved in the outer lip : another, however, with the same twisted columella, presented the ordinary indentation in the labrum. 243. IANTHINA DECOLLATA, nom.prov. I. t. globosa ; spird plus minusve extante, pallide violaced ; anfractu ultimo pallidissimo, basim versus violaced ; apice corneo, deciduo ; nucleo obliquo, haud extante ; suturd profundd ; labro varie sinuato ; columella vix contortd ; labio haud por- recto, umbilicum scepe tegente. Comp. lanthina globosa, Swains. Zool.ILl. vol. ii. pi. 85, fig. med. Comp, lanthina prolongata, DOrb., B. M. Cat. Cuba Moll. p. 23, no, 259 ; B. M. Cat. D'Orb. Moll. p. 35, no. 317 ; non Desk, in Lam. An. s. Vert. vol. ix. p. 5, no. 3. This shell is most closely related to the West Indian species, differing from the specimens examined simply in colour, which instead of being equally diffused on the shell, is confined to the .base and spire. It differs from I. prolongata of the Medi- terranean and Canaries in the very slight contortion of the columella, which in the Europsean species resembles that of Lymnsea (Desk.) If the I. globosa of Swains, represents the W. Indian shell, and not the I. prolongata, as Desh. and Gray suppose, this shell may prove identical with it, when more specimens have been found from other localities. The Mazat- lan specimens, though very few, differ considerably in the greater or less exsertion of the spire, inflation of the shoulder and base of the body whirl, and concealment of the umbilicus. The sinuation of the outer lip varies not only in different speci- mens, but in the same shell at different periods ; being some- times scarcely waved, at others strongly angulated as in I. fragi- lis, sometimes with a semicircular medial sinus. The nucleus is sunken, rather oblique, with the apex horny and always de- collated. In I. prolongata, it is exserted and persistent. The largest sp. measures long. 1'02, long, spir. "3, lat. "87, div. 105. A swollen sp. measures *83, *13, *81, 130. Sab. Mazatlan ; with I. striulata, extremely rare ; L'pool Col. Tablet 878 contains 3 specimens. 188 MAZATLAN UNIVALVES OBDEB LATEBIBBANCHIATA, Clark. FAMILY DENTALIAD.E. GENUS DENTALIUM, Linn. The fullest account of the animal of this remarkable tribe, will be found in Clark, Moll. Test. Mar. Brit. pp. 225238. It has only a faint analogy with Fissurella ; and differs so much from even the most aberrant of the Scutibranchs that the Order, proposed by Clark, is adopted. There are many points of analogy with the Lamellibranchiate Mollusca, and some with the Annelids. Individuals appear to be very rare at Mazatlan, perhaps in consequence of the scarcity of For- aminifera, on which these blind, almost headless creatures voraciously feed. 244. DENTALIUM LIBATUM, n. s. D. t. solidd, alba, tereti, liris longitudinalibus tenuissimis creberrime indutd ; liris in junior em circiter xii., in adultam circiter xxx., acutis, baud cequalibus ; parum arcuatd, aperturd branchiali simplici. One perfect, though rather small, specimen was found en- tangled in the byssus of Modiola capax ; fragments occurred of a much larger size. Long. '25, lot. 'Oil '03. Hab. Mazatlan ; off Modiola capax, Chamse and Spondyli, . very rare ; Lpool Col. Tablet 879 contains the perfect specimen, a small do. wedged in the mouth of Trivia sanguinea, and a fragment of a large one, '065 across. 245. DENTALIUM HYALINUM, Phil. Zeit.f. Mai. 1846, p. 55, no. 27. Tablet 880 contains a minute shell of a hyaline texture, with an opaque line running along the inner curve, which may be accidental. It probably belongs to the above species des- cribed by Philippi from Mazatlan, although that is said to be "versus apicem tenuissime striata, " while this, which is ex- tremely young, is smooth. Long. '07, lat. '01 '025. Hob. Mazatlan ; 1 sp. off Spondylus calcifer ; L'pool Col. MAZATLAN UNIVALVES 189 246. DENTALIUM CORRTJGATUM, n. s. D. t, albido-corned, subdiaphand, parum arcuatd, gracili, superjicie concentrice irregular it er corrugatd, rugulis minimis, confertissimis ; aperturd brancJiiali simplici. One very young specimen only was found of this species, remarkable for its concentrically wrinkled surface. Long. '05, lat. '005 '01. Hab. Mazatlan ; 1 sp. off Spondylus calcifer ; Lpool Col. Tablet 881 contains the specimen. 247. DENTALIUM ? PRETIOSUM, Nutt. (teste lids.) Tablet 882 contains a fragment of a smooth species. It is affiliated to the above, because a specimen in Mr. Darbishire's collection, brought along with Lyonsia diaphana, seems to have come from Mazatlan. This latter, a very small one for the species, measures long. 1*56, lat. '05 '15. Hab. ? Mazatlan ; extremely rare, off Chama ; L'pool Col. ORDER SCUTIBBANCHIATA, Gray. Scutibranchiata + Cyclobranchiata + Pectinibranchiata (pars) Cuv. FAMILY CHITONID^. Our knowledge of this most aberrant family is very incom- plete. Many genera have been proposed by Dr. Gray in the Proc. Zool. Soc. 1847, pp. 63, 126, and others by II. fy A. Adams, Gen. vol. i. pp. 467-484 ; and others by Dr. Shuttle- worth of Berne. This fullest account of their physiological structure will be found in "Middendorjfs Malacozoologia gia Rossica, St. Petersburg, 1847, Part I ; Beschreibung und Anatomic ganz neuer oder fur Russland neuer Ckitonen ; " in which 152 large 4to pages, and 14 plates are devoted to the elucidation of 21 species. Additional information is given in his "Seise in den Aussersten Nor den und Osten Sibiriens, Part II. St. Petersburg, 1851," pp. 163-183, pi. 13-15. Most of the Mazatlan species are extremely small. None of them are known to inhabit any other district, except Lophyrus sanguineus, about which there is still some doubt. Throughout the world, they appear to be among the most local of shells. 190 MAZATLAN UNIVALVES In the following descriptions, as far as practicable, the terms are employed as proposed by Middendorff, Mai. Ross. p. 36. By ihejugum is meant the ridge running along the middle of the valves ; the mucro is the apex on the posterior valve : the valve-lobes are the prolongations of one valve which fit under the next ; the sinus lies between them. GENUS LOPHYBUS, Poli. H. fy A. Ad. Gen. vol. i. p. 469. Radsia + Gymnoplax, Gray, Chiton, pars, auct. Plates of insertion in denticulated lobes ; integument tessellated with smooth scales. 1 248. LOPHYBUS AETICULATUS, Sow. Chiton articulatus, Sow. in Proc. ZooL Soc. March, 1832, p. 59 -Conch. III. no. 29, f. 18. Zool. Beech. Voy. p. 150, pi. 41, f. 16. Lophyrus articulatus, H. fy A. Ad. Gen. i. 470. The figure in the Conch. III. is very accurate ; but that in Seech. Voy. represents much too strong a sculpture. The Mazatlan specimens rarely display any sculpture at all, being almost universally eroded, even in young specimens. The plainness of the exterior is however abundantly compensated for by the great beauty of the inner structure of the valves, which the large number of specimens sent allow to be freely examined. The form is sometimes broad, with nearly straight sutures ; sometimes elongated, with arched back, and sutures bent, occasionally into the form of a ^ , -- . Very rarely the shell is indented on each side of the jugum, rudely present- ing a likeness to a Trilobite. The surface of the valves, when perfect, is crowded with minute pustules ; diagonal lines scarcely marked. Colour olive green shaded into reddish brown at the ridge, with irregular longitudinal streaks of brown olive on each side : faint narrow rays of the same tinge on the terminal valves, and irregularly waved penciling over the surface of the diagonal areas. Inside bluish green ; valve- lobes long and flattened, with a broad medial sinus. The surface within, under the microscope, is extremely finely cor- rugated. The margin is formed of fine, irregular plates, each sometimes branching into a plume ; these are interrupted in the medial valves by one slit on each side, in the terminal ones by 14 20. From these proceed rows of punctures to the axis MAZATLAN UNIVALVES 191 of the shell ; in the young state visible within, in the adult concealed, but generally traceable in the eroded surface. At the junctions of the valves, close above the valve-lobes, may be seen rows of large open cells, with smaller ones above, somewhat resembling the parenchyma of a leaf cut across. Along the sinus is another row of plates as in the margin. The structure of the shell presents many points of analogy with the Cirripedes : as does the animal with others of the Articulata. The integument is crowded with very deciduous, hard, green scales, sharply jointed, having 3 sides, of which one is corru- gated, the others smooth . They are somewhat of the shape of a pistachio nut. The following measurements are not perfectly exact, in consequence of the curvature of the specimens. A broad specimen measures long. 2 '7, lat. 1'7, div. 120. The largest specimen 4'2, 2'2, 105. Sab. San Bias, under stones, Beecliey. Mazatlan ; abundant, but much worn ; L'pool Col. Tablet 883 contains 4 sp. in the usual condition. 884, 1 do. very perfect. 885, 3 sp. broad form. 886, 2 sp. elongated. 887, 2 sp. surface eroded, displaying the inner structure. 888, 1 sp. with very irregular margins, and Coiiia attached. 889, 1 sp. obscurely trilobed. 890, 2 sp. with head valves abnor- mally large, perhaps from limpets attached. 891, valves of very young sp. 892, 2 sp. valves separate to shew structure. Tablet 893 contains an extremely young specimen, '16 in length, which probably belongs to this species. The valves are more strongly pustulose, and the marginal scales much larger in proportion than in the adult. There is also a row of hairy processes at the mantle margin, below the scales, which may be connected with the gills. It has more the aspect of C. lamgatus, Sow. Proc. Zool. Soc. 1832, p. 59 : Condi. III. sp. 30, f. 18*, which is from the same locality, and may prove to be only a variety of C. articulatus. 219. LOPHYEUS ALBOLINEATUS, Brod. fy Sow. Chiton albolineatus, Zool. Journ. vol. iv. p. 368. Sow. Conch. El. sp. 42, f. 39. Zool. Beech. Voy. p. 149, pi. 40, f. 4. Rve. Conch. Ic. Lophyrus albolineatus, H. fy A. Ad. Gen. i. p. 470. This beautiful species is remarkable for the different appear- ance of valves on the same specimen, which may be either 1 192 MAZATLAN UNIVALVES albolineate or quite black. Normally there is a black line on the ridge, bounded by two white ones ; diagonal areas and terminal valves white, penciled with brown in finely waved transverse lines. Besides the colour, shape and delicate tex- ture, it differs from the young of L. articulatus in the following particulars. Surface (under the microscope) regularly granu- lated in diagonal rows ; granules larger in proportion. Radia- ting lines of punctures almost always visible within. Plates of insertion in simple rows, not plumed. Sinus with irregular transverse incisions internally. Substance of valves next the lobes with a row of larger cells. Scales of margin more grey, rounder, more deciduous. In the young shell, the granules on the diagonal areas are much larger in proportion. In addition are seen extremely fine striae, diagonal over the areas, longi- tudinal over the rest. The marginal scales- are much larger in proportion, and are bounded by a row of gill-like hairy pro- ceses, as in the young of the last species. The largest specimen measures long. 1'8, lat. '9, div. 115. Hob. Mazatlan ; Belcher. Do. ; rare ; L'pool Col. Tablet 894 contains 3 extremely young specimens, the small- est '18 in length. In one, most of the valves are separate, displaying the same structure as in the adult. The mantle shews clearly the marks of insertion ; and, with the dried remains of the animal, is so transparent that the lingual ribbon is clearly traceable within, '04 by '0075 in. Tablet 895 contains three specimens ; the largest, one with the margin perfect, and one with black valves intercalated. 896, 2 sp. with the valves separate, and 2 nearly black valves to shew structure. 250. LOPHYEUS STEIATO-SQUAMOSUS, n. S. L. t. subrotundatd, depressd (ad anqulam 140V, pallidefusco- olivaced ; valvis totd superficie dense granulatis ; areis laterali- bus satis distinctis ; valvis latis, vix curvatis s vix mucronatis ; jugo vix distincto, tenuissime longitudinaliter striato ; marginibus later alibus planatis : mucrone superior e, vix distincto ; limbo pallii squamis solidis, ovalibus, magnis, haud confertis, instructor squamulcB cujusque dimidio alte striato ; marginibus valvarum serratis, fissuris in valvis intermediis una in latere utroque, in valvis terminalibus circiter xii. j valvarum lobis magnis, valde arcuatis. MAZATLAN UNIVALVES 193 The serrations of the margin in the only perfect specimen found are distinctly visible through the dried cuticle, as they are also in some dead valves in other respects agreeing with the shell, Below the large scales of the mantle margin appears a row of gill-like flattened hairs, as in the young of L. artieu- latus and albolineatus. Long. '17, lat. '12, alt. '04. Hob. Mazatlan ; 1 sp. off Spondylus oalcifer ; L'pool Col. Tablet 897 contains the specimen. GENUS PTONICIA, Gray. Proc. Zool. Sec. 1847, p. 65. H. fy A. Ad. Gen. vol. i. p. 473. Chiton, pars, auct. Plates of insertion as in Lophyrus : mantle smooth. 251. ? TONICIA FORBESII, n. s. ? T. t. ovatd, subelevatd fad angulam 115^ brunned, olivaceo varie pictd ; valvis intermediis mucronatis, sulcis injugo \l~for- mibus a mucronibus projicientibus decurrentibus ; lineis diagon- al ibus v aide tuber culatis ; areis later alibus sparsim punctatis, ad valvarum interstitia tuber culato-corrugatis ; areis centr ali- bus rugis curvatis divergentibus, in valvis terminalibus circiter xiii. ; mucrone conspicuo ; limbo pallii sublcevi, lenuiori ; valvarum lobis intus dcclivibus, sinu alto, lato ; jugo intus roseo ; marginibus valvarum et sinus dense serratis, Jlssuris in valvix intermediis und in latere utroque, in valvis terminalibus rugis externis convenientibus. Two specimens were found of this very beautiful species, which is dedicated to the memory of the learned and deeply lamented. Prof. !E. Forbes, whose promised assistance, had lie lived, might have prevented many errors in the present work. Neither of the specimens shew any trace of imbricated scales, though they may possibly exist. The structure of the marginal plates closely resembles that of Lophyrus albolineatus. Loin,-. '78, [lat. '45, alt. '14. Hab Mazatlan ; extremely rare ; L'pool Col. Tablet 898 contains the finest specimen; the other is in Mr. Darbishire's cabinet. April 1856. s 194 MAZATLA:^ UNIVALVES GENUS LEPIDOPLEUEIJS, Eisso. H. $ A. Ad. Gen. vol. i. p. 471. Ischnochiton, Grray, Proc. Zool. Soc. 1847, p. 126. Mantle scales very minute, grooved : insertion-plates thin, smooth-edged. 252. LEPIDOPLEURUS SANGUINEUS, Eve. Chiton sanguineus, Eve. Conch. Ic. pi. 17, f. 98. Comp. Chiton limaciformis, Sow. Proc. Zool. Soc. 1832, p. 26 : Conch. III. sp. 58, f. 38. Eve. Conch. Ic. pi. 8, sp. 42. (Co- lumbia, Sow. : Inner Lobos Is., Peru, and Guacomayo, under stones at low water, Cuming.) This is probably not the Ch. sanguineus of Guilding, from St. Vincent's, which is quoted by Reeve in the Conch. Ic. ; and is certainly not the Ch. sanguineus of Dr. Cutting, from Barbadoes, in the Bristol Museum. It is however identical with the specimens in the Cumingian collection, and most closely resembles Ch. limaciformis. There may be a difference in the integument, which the imperfect state of the specimens has failed to display* The Mazatlan shells are more generally tuberculated on the terminal valves than on the typical speci- mens of the species. The mode of attachment is quite different in this shell from that of Lophyrus. The valve margin has an outer and an inner rim ; the outer being a simple continuation of the exter- nal shell layer ; the inner being a white, sharp ridge, cut by 10 14 slits in the terminal valves ; so as to give the appear- ance of a lip with a row of incisor teeth within. The central valves have one slit. The radiating punctures are elongated. Inside rose-coloured; outside brownish, pink, or dark olive green, or brown, or yellowish irregularly spotted with green. Surface deeply furrowed with irregular longitudinal lines, waved at the sharply angular diagonal lines. The terminal valves are tuberculose, finely so above, coarselybelow. Interior surface finely corrugated and ridged for the muscular attach- ments. Valve lobes small, arched ; sinus very large. The valves are easily loosened from the membrane, which is generally thin and smooth, sometimes with an irregular whitish deposit, apparently not of organic matter. Long. 1'04, lat. '4, div. 105. Hob. Mazatlan ; very rare ; ISpool Col. Tablet 899 contains 4 sp. various colours. 900, 2 sp. opened to shew the valves. MAZATLAN UNIVALVES 195 253. LEPIDOPLEURUS CLATHKATUS, n. s. L. t. subrotundatd, depressd, (ad angulam ISO^Jfusco-oliva- ced ; valvis latissimis, marginibus lobatis, interstitiis subrectis ; valvis intermediis, injugo et (plus minusve) totd superjicie granu- latis; costis duabus, tubcrculispravalidismunitis, und diagonali, allerd supra marginem decurrente ; areis lateralibus parvis, granulatis ; areis centralibus clatkris iv. utroque in latere longitudinalibus munitis, clatkris tuberculatis, interstitiis gran- ulatis ; valvd anticd costibus radiantibus circiter xi. rotundatis, subtuberculatis ; limbo pallii latissimo, squamulis minimis, mollibus, conferto ; marginibiis valvarum simplicibus, antico fissuris ix. ad costas Jiaud convenientibus, testa externd, quasi subgrundd, circumeunte. One very small specimen was discovered on a stone to which a OiTLcibulum had been attached, beautifully perfect except in the loss of the anterior valve. A dead anterior valve was found of a much larger specimen, displaying a marginal structure like that of L. sanguineus. The shell is remarkable for the strong bars across the ventral areas, and the stout rows of tubercles which run, the one diagonally, the other along the interstitial margin. The mantle is very broad, and crowded with minute scales. Long. *17, lat. '12, alt. '02. Hob. Mazatlan ; under stones, extremely rare ; L'pool Col. Tablet 901 contains the specimen. 254. LEPIDOPLEUEUS BULLATTJS, n. s. L. t. subovatd, elevatd (ad angulam 110V olivaced ; valvis intermediis lineis diagonalibus bullis extantibus ornatis ; areis lateralibus angustissimis, tuberculatis, inter 'dum bullis munitis ; areis centralibus lineis tubercularum, in utrdque parle circiter vii., lineis diagonalibus perpendicidaribus : interstitiis ubique granulatis ; valvis terminalibus lineis bullarum radiantibus circiter xi., mucrone subconspicuo ; limbo pallii lato, pilulis minimis instructo ; valvarum lobis biangulatis, sinu alto ; marginibus valvarum simplicibus., in valvis intermediis Jissurd uno, terminalibus circiter vii., margine externo tegente. One fresh specimen (somewhat crushed in extraction) and a few perfect valves were found of this species, which is charac- terized by the very strong row of tubercles, (like pebbles) which lie on the diagonal line ; by the rows of somewhat strong tuber- cles on the central area, running perpendicularly from the 196 MAZATLAN UXIVALVES diagonal towards the jugum ; and the granules over the whole surface, somewhat corrugated on the jugum. The internal plates of all the valves have an external projection from the outer siirface, as in L. sanguineus. Long. '17, lot. '12, alt. '03. Hob. Mazatlan ; off Spondylus calcifer, extremely rare : L'pool Col. Tablet 902 contains the sp. and 2 odd valves. 254, b. LEPIDOPLEURUS BULLATUS, var. CALCIFEEUS. L. ? bulletins, areis lateralibus ' tuber culatis, sine bullis, lined diagonals quasi calculis instructd ; areis centralibus lineis tuber- cularum irregularibus, tuberculis minoribus ; pilulis pallii majoribus, confertissimis. Tablet 903 contains one specimen which presents the above differences. Whether they be specific, cannot be determined without other and older specimens. Hab. Mazatlan ; 1 sp. off Spondylus ; L'pool Col. 255. ? LEPIDOPLEURUS MAC-ANDREI, n. s. ? L. t. "Lopkyro striato-sqiiamoso" valvis et limbo pallii fere omnino simulante, sedmarginibus valvarum acutis, kaudserratis. A smashed specimen in fresh condition was found on a Spondylus, not distinguishable externally from Lophyrus striato-sguamosus, but unexpectedly presenting the sharp in- sertion-plates of Lepidopleurus, at the same time that the scales agreed exactly in the remarkable character of the former species. Not daring to build on such imperfect data, I sus- pended my judment : but when examining some specimens of Margaritiphora Mazatlanica in the collection of T.lN"uttall,Esq., I was fortunate enough to discover between two laminae a per- fect little Chiton, which on examination turned out to be exactly identical with the smashed specimen from the Spondylus. Having loosened a terminal valve, and subjected it to repeated examinations under a half-inch achromatic, I am unable to dis- cover any trace of serration,* while in L. striato-squamosus it is unmistakably evident. In the absence of further evidence, we are obliged to conclude, either (1) that the same species * In examining young Chitons, it is necessary to guard against being misled by the gill-like lamina, which, passing over the insertion -plates, is apt to give them (under a low magnifier) a serrated appearance. MAZATLAN UNIVALVES 107 may adopt both forms of marginal insertion at different periods of growth, which is contrary to our observation in the young of other species ; or (2) that a different creature, belonging by its plates to one genus, puts on the exact appearance of a species in another, even to the very conspicuous scales, which are for- bidden by the diagnosis to Lepidopleurus, and are also striated which is equally forbidden in Lophyrus. Under either suppo- sition, it would appear that we have not yet attained a correct knowledge of the principles of division to be adopted in this most remarkable family. Long. '13, lat. "08, alt. .025. Hab. Mazatlan ; on Spondylus calcifer, extremely rare ; L'pool Col. Tablet 904 contains the perfect specimen, kindly presented by T. Nuttall, Esq. Of its habitat nothing is certainly known. The Avicula to which it adhered was exactly like the Mazat- lan shells ; and there were also found on its surface several specimens of Septifer Cumingianus, and two of a species of Csecum, both identical with those from Mazatlan. 256. ? LEPIDOPLEUBUS BEANII, n. s. ? L. t. ovatd, elevatd (ad angulam 110^, fusco-olivaced, sen albido cceruleoque maculatd ; valvis intermediis valde mucrona- tis, inierstitiis curvatis, marginibus subrotundatis ; valvd pos- ticd depressd, excavatd, mucrone minima, super ior e ; jugo ef- areis lateralibus indistinctly : superficie totd granulis instructd, " et punclulis minimis confertim ornatd : valvarum lobis magnis, curvatis, sinu planato ; marginibus acutis, fissuris circiter x. valvis terminalibus, nnd in utroque latere, intermediis ; margin./'- bus externis prominentibus ; limbo pallii piluloso, spinulis par- vis, erectis, planatis. Differs from L. Mac-Andrei in being longer, with the valves mucronated and rounded at the extremities, the posterior being hollowed out, and the rest much elevated, without con- spicuous middle portion or lateral areas. The only perfect specimen found (on Acmgea fascicularis) displays no trace of solid scales. The account of the interior is taken from a large central and small anterior valve supposed to belong to this species from their agreement in other respects. Long. '23, lat. *13, alt. '04. JLab. Mazatlan ; extremely rare ; L'pool Col. Tablet 905 contains the perfect specimen off Acmsea, and the two valves. 198 MAZATLAN UNIVALVES GENUS CHITON, Linn. Chiton, pars, auct. H. fy'A. Ad. Gen. vol. i. p. 474. Acan- thopleura, G-uild. ; Gray in Proc. Zool. Soc. 1847, r p. 67. Margin spinose : insertion-plates in terminal valve rnany- lobed, in middle valves bi-lobed. 257. CHITON FLAVESCENS, n. s. Cli. t. ovatd, valde depressd (ad angulam 150j flavidd, aurantio maculatd ; valvis latis, marginibus subrotundatis, interstitiis curvatis, valde mucronatis ; areis lateralibus et jugo indistinctioribus ; mucrone parvo, superiore ; totd superficie granulis rugulosis confertim instructd, hand punctulatd ; limbo pallii crasso, sublcevi, ad marginem spinulis tenuibus, erectis, planatis instructd ; valvarum lobis, magnis, arcuatis, simi maxima ; marginibus valvarum intermediaruin fissurd duos in lobas divisis, quarum unaparva, lineis punctorum utrdgue in parte adjugum decurrentibus ; valvarum ultimarum marginibus subacutis,jissuris circiter x. This is the least uncommon of the small Chitons, six speci- mens having been found of it. It is distinguished by its yellow colour, great depression, and small strong mantle margin, without covering, except at the margin where a fine row of transparent flattened hairs may be seen. The smaller lobe on the margins of the inner valves is- bounded by two rows of holes which proceed to the jugum. Long. '16, lot. '11, alt. '3. Another specimen, rolled into a ball, is larger. Hob. Mazatlan ; on shells, very rare ; If pool Col. Tablet 906 contains the largest specimen ; another in situ on a broken crevice of Crepidula ; and 2 separate valves. GENUS ACANTHOCHITES, Eissg. G-ray, Proc. Zool. Soc. 1847, p. 66 : H. $ A. Ad. Gen. vol. i. p. 482. Chiton, pars, auct. Mantle with tufts of bristles. 258. ACANTHOCHITES AEKAGONITES, n. S. A. t. elongatd, elevatd (ad angulam 110% pallido-fusca, olivaceo et roseo variepictd : valvis intermediis valde mucronatis, interstitiis a mucronibus valde divergentibus ; jugo lato, pallido, MAZATLAN UNIVALVES 199 tenuissime longitudinalitcr granulato-striato, transversim minu- tissime corrugato ; areis later alibus indistinctis ; superficie tota valde gnanulatd, tuberculis splicer oidalibus et granulis catenatim in lineis a jugo sub diver gentibus elegantissime in- structd ; mucrone subconspicuo, subcentrali ; intus rosed seu alba ; marginibus acutis et lobis valvarum non separatis, mag- nis,fissura in utroque latere und, lobis angulatis, sinu maxima, planato ; ad jugum tenuissime corrugatd, ad mucronem lamin- aid ; valvd posticd hexagonali, duabus Jissuris ad terminum divisd ; limbo pallii spiculis erectis translucidis copiose ornato ; postice, antice, et ad suturas, spicularum quasi acicularum cristis pulcherrime munito. Whether the varied colouring of this shell, its elegant sculp- ture, the bird-like form of the medial or hexagonal shape of the bifissured terminal valves, or the adornment of the mantle with transparent needle-like hairs, rising now in tufts, now in irregular crystals, be examined under the microscope, it would be difficult to find any shell of such surpassing beauty. Only one perfect specimen was found, but fresh valves belonging to several other individuals were detected among the Spondylus washings. The valves in the same shell greatly differ in colour, as in L. albolineatus. The posterior valve is peculiarly exqui- site in its form, colour and sculpture. There is considerable variation in the size of the tubercles, and in the striation of the jugum. The outer margin does not enclose the plates of insertion, as it does in Lepidopleurus. Long. '16, lat. *06, alt. '02. Hab. Mazatlan ; off Spondylus calcifer ; extremely rare ; L'pool Col. Tablet 907 contains the perfect specimen and 4 valves. FAMILY PATELLID^E. GENUS PATELLA, Linn. As the shells in this genus can scarcely be distinguished from those of Acmsea, the location of many of the following species in this and the next family is doubtful. 259. PATELLA MEXICANA, Brod. fy Sow. Zool. Journ. vol. iv, p. 369. Menke in Zeit.f. Mai. 1851, p. 37, no. 132. =Lottia gigantea, B. M. : Gould ms. = Patella maxima, B. M. Cat. D'Orb. Moll. p. 53, no. 449. 200 MAZATLAN UNIVALVES Shell extremely large ; white, or of a yellowish or greenish tinge, occasionally orange ; with a broad marginal band of a semidiaphanous hue, very conspicuous in the young shell. Muscular scar in adult raised, irregularly lobed and corrugated. The outside is frequently covered with Algae and bored by Lithophagi. Its surface is a favourite place of adherence for smaller limpets. In the young shell may be traced about 10 very indistinct principal ribs, with a profusion of radiating lirulse. These however very soon disappear. The youngest ascertained specimen measures long. 1*65, lot. 1*4, alt. '42. The>rgestsp. 9'2, 6*9, 4'5. A flatter do. 9', 7'1, 3*6. Hob. Mazatlan, Beecheys Voyage. Do., Menke. Do. ; abundant, L'pool fy Havre Coll. Monterey, Col. Jewett, (G-ould ms. :' non Nutt.) Payta, Peru, jyOrbigny. Tablet 908 contains 3 young sp. different ages. 909, 1 sp. finely grown, adolescent, margin flattened. 910, 1 do. margin sharp, muscular scar thick, brownish red. 911, the largest sp., outside riddled by Lithophagi. 260. PATELLA PEDICULUS, Phil. Zeit.f. Mai. 1846, p. 21, no. 8. =P. corrugata, Eve. Conch. Ic. sp. 132, pi. 40, f. 132, a, b. (1855.) Comp. P. Araucana, B. M. Cat. D'Orb. Moll. p. 53, [no. 448 : (=however P. zebrina, var., teste Gray in loco.) Shell normally flat, oblong, solid, with 10 stout rounded ribs projecting at the margins, of which 2 are in the axis of length with 4 on each side : ribs and interstices radiately striated : yellowish white, generally with more or less of black or brown tortoise-shell markings within, sometimes with the black be- tween the ribs as described by Phil, and Eve. Sometimes the shell is more rounded and the ribs rather angular, in which state it might be taken for the young of P. Mexicana. Occa- sionally a few other intercalary ribs appear. In a very few unusually large specimens, the ribs are nearly 'obsolete at the margin and the shell is much lengthened. The body mark varies as usual ; when plain, it is gathered into points as in P. discors. The very young shells appear not to develop the ribs marginally, in which state they might be taken for the young of P. discors. The stout ribs of the adult shell however bear no analogy with the very finely marked surface of the latter with its curiously puckered circurn-unibonal portion. With the MAZATLAN UNIVALVES 201 young of P. Mexicana it lias much closer analogies. The largest specimens of P. pecliculus however do not at all run into the smallest of P. Mexicana. They have all the appear- ance of being old shells, with the margin narrow and the shape long and irregular ; while P. Mexicana, as it is traced upwards, displays a very wide semitranslucent margin, and a broad regular shape, with the ribs not rounded and prominent but simply giving an angular form to the shell. To settle the point satisfactorily will require a series of P. Mexicana from its earliest stage, as well as a knowledge of the animals. Of this species I have carefully examined nearly 300 specimens. The youngest shell that has its ribs developed and clearly belongs to this species is ' 17 long. Tablet 912 contains two smaller ones without distinct ribs, which probably belong to it* Even when very young, they arc almost always incriisted with corallinous matter. The largest specimen measures long. 1*3, lat. 1', alt. *4. The ordinary size however is very much smaller and natter. Hob. Mazatlan, Philippi. Acapulco, Reeve. Mazatlan ; not uncommon ; L'pool fy Havre Coll. Tablet 913 contains 3 young specimens. 914, 3 sp. ordinary state. 915, 3 do. ribs well developed. 916, 3 do. light tortoise- shell within. 917, 3 do. dark tortoiseshell. 918, 3 do. broad variety. 919, 4 do. ribs numerous. 920, 4 do. elongated, ribs small. 921, 1 sp. abnormally elongated, with very small ribs. 922, Patella discors, with place of attachment of P. pediculus. I 261. PATELLA DISCOES, Phil. Abbild. und Besch. Condi, pi. 2, f. 6. Rve. Condi. Ic. sp. 78, pi. 29, f. 78, a, b. The peculiar characteristic of this species, viz. the crumpling near the umbo, is very seldom seen without careful cleaning, as the shell is almost always thickly coated with vegetable corallinous deposits, algae, &c. The surface is extremely finely ribbed throughout, but at a little distance from the black apex the shell is gathered into irregular undulations, about 15 (more or less) which soon disappear, and leave the shell henceforth of a regular growth. It goes through all the changes common to limpets, being sometimes high, sometimes depressed ; some- times suborbicular, generally oval. The margin is extremely finely crenated, and is generally more or less dotted with black. The prevailing colour is a greenish white, with more or less 202 MAZATLAN UNIVALVES distinct radiating black lines. Sometimes the internal surface is beautifully mottled with purple or brown. The animal mark is by no means constant in shape ; but, when well denned, shews the body gathered pretty regularly into points with curves between. The smallest specimen is about '25 in length ; the largest measures long. 2 '15, lat. 1'7, alt. '72 Hab Mazatlan, Lieut. Shipley $. W. Mexico, P. P. C Mazatlan very common ; Lpool fy Havre Coll. Tablet 923 contains 4 sp. various ages. 924, 4 specimens white. 925, 5 do. greenish tinge. 926, 4 do. coloured within. 927, 4 do. tortoiseshell. 928, 8 sp. yellowish tinge. 929, 4 do. very faint appearance of marginal dots. 930, 7 do. a shade more developed. 931, 8 sp. black rays coated over. 932, 7 sp. black dots distinct. 933, 7 do. more distinct. 934, 7 do. well developed. 935, 5 sp. faint black dotted margin. 936, 5 do. distinct black margin. 937, 6 sp. with brown tortoiseshell markings. 938, 5 do. purplish tinge. 939, 4 do. black and brown. 940, 3 sp. body mark distinct. 941, 3 sp. margin abnormally indented. 942, 5 sp. irregular internal growth. 943, 1 do. with large Balanus, Lithophagus, &c. GENUS NACELLA, Schum. Patella, pars, auct. 262. NACELLA, -- , sp. ind. Tablet 944 contains a solitary specimen of a Nacella, of the shape and size of Ancylus fluviatilis, with the apex spirally recurved, and of a dark horny colour. It is not perfect enough for description. Hal. Mazatlan ; off Chama, 1 sp. ; L'pool Col. FAMILY GENUS ACM^EA, Esch. Eschscholtz Zool. Ail. ed. Rathlce, 1833, p. 16, (diagnosi copiosa.) Forbes fy Hani. Br. Moll. vol. ii. p. 434. Woodio. Man. Moll. p. 155. Phil. Handb. Conch, p. 199. (Non Acme, Hartm. 1821.) Lottia, Gray in Phil. Trans. 1833, and in Sow. Gen. 1833. Patelloida, Quoy fy Gaim. 1834, Voy. Astr. vol. iii. p. 349. Tectura, Audouin fy Milne Edw. Ann. Sc. Nat. 1830, vol. xxi. p. 226, (Gray : p. 325, PMLJH. $ A. Ad. Gen. vol. i. p. 458. MAZATLAN UNIVALVES 203 4-263. ACM.EA MESOLEUCA, Mice* A. t. "Acmceis patince et testudinali" simili ; tenui, subdia- phana, rarius solidiore : extus, apicem versus Icevi, postea lirulis tenuibus subdistantibus irregularibus ornatd, scepe minutissime granulatis, interdum crassioribus, appropinqiiantibus ; fusco- olivaced, interdum fused, rarius* nigro-fuscd ; varie tessellatd, lineatd sen maculatd, interdum unicolore : intus, margihe fusco et albido, seu nigro-fusco ; medio plus minusve viridi, seu albido- viridi, interdum Jlavescente seu fiavido-viridi ; spathuld fused, seu fuseo-olivaced, capite subtriangulari, corpore interdum ir- regulariter pectinato. Mice, in Zeit.f. Mai. 1851, p. 38, no. 135, (diagn. supra auct.) ? + A. mutabilis, pars, Mke. loc. cit. p. 37, no. 133. = Patella diaphana, Eve. Conch. Ic. pi. 24, sp. 61, f. 61, a, b, 1854. ? = Patella diaphana, Nutt. in Jays Cat. no. 2813, (sine diagn.) ?=Lottia patina? C. B. Ad. Pan. Shells, p. 241, no. 367 (non A. patina, Esch.) Pars ? = Patella (Acmsea ?) personoides, Midd. Mai. Ros. pt. ii. p. 37, no. 10, pi. 1, f. 2, 1849 : (=A. ancyloides, Mid, olim, non Propilidium ancyloide, Forbes.) Var. ? = Patella (Acmsea?) seruginosa, Mid. Bui. Acad. St. Pet. vol. vi. no. 20: Mai. Eos. pt, ii. p. 38, no. 11, pi. 1, f. 1. = Lottia pintadina (pars) Gould Exp. Shells, 1846, p. 9. Comp. Patella floccata, Rve. Conch. Ic. vesper tina, Rve. loc. cit. pi. 26, f. 67, a, b. ,, Cumingii, Rve. loc. cit. pi. 16, f. 37, a, b. Var. = Patella striata, Rve. loc. 'cit. pi. 33, f. 99, a, b.: (non Patelloida striata, Quo?/ fy G-aim. Voy. Astr. Moll. pi. 71, f. 811 : Rye. Conch. Ic. sp. 58.) = Acmsea Antillarum, P. P. C. Cat. prim.: non Sow. (=A. testudinalis, teste Grould Inv. Mass.) = Acmsea patina, P. P. C. Cat.prov. (non Esch .) * It is difficult to say which name should be retained for this species. It is figured as P. diaphana by Reeve, the name having been received by Mr. Cuming from Jay as of Nuttall. Mr. Nuttall's own specimens however of the green lim- pet are from Mazatlan, nor does he remember taking them in California ; and it is probable that he gave the name to the parallel variety of A. patina, to which the green shells brought by Hinds, Kellett, &c. were affiliated. At any rate it can only claim priority from the date of its appearance in Reeve. Gould's name would have been retained, but that unfortunately his type specimens consist of P. verriculata, leucophaea and scabra, Rve., with A. mesoleuca and iascicularis, Mke. If one or both of Middendorff's species should prove identical with the Mazatlan species, the name A. personoides shoujd be retained : but even that author's very copious descriptions do not allow us to speak with confidence, without a comparison of types. Under these circumstances, as Menke's name, though given later, certainly represents the Mazatlan species in its usual state, it is thought best to retain it. 204 MAZATLAN UNIVALVES This species, and its more temperate analogue, A. patina, go through the same varieties of forni and pattern ; some of which are so divergent that it is not to be wondered at that they have been described as distinct ; and others are so marvelously alike that they can scarcely be separated from each other by figure or description. The habit however of the two species is sufficiently distinct ; and those who have examined large multitudes of specimens will have little difficulty in separating them. The simplest guide is the prevailing green and brown colour of this species, and the prevailing white and black of the other. The character of the ribs, which is mainly relied upon by Middendorff, appears subject to great variation. Shell extremely variable in colour and markings, but gene- rally rather broad and flat, with the apex somewhat inclined anteriorly, especially in the young shell. Outside with the apex and sometimes a considerable portion of the shell nearly smooth ; generally with extremely fine ribs, sometimes sharp, sometimes rounded, generally slightly granulose ; sometimes with broad strong ribs ; sometimes nearly smooth with radiat- ing lines of granules. Sometimes intercalary ribs are found, much larger than the rest ; sometimes different plans of sculp- ture are seen on the same shell. The colour outside is generally olive or brownish green ; sometimes without markings, gener- ally with white lines either radiating or broken up ; often with white patches tessellating with the brown ; or changing from one pattern to another. Inside the shell is generally whitish about the middle, (whence the name,) with more or less of a bluish green tinge, sometimes dark green, sometimes brownish, sometimes with an element of ochre yellow more or less mot- tled, (? P. seruginosa, Mid.} There is almost always a large dark spot at the body mark, of a brownish olive green, in which sometimes the brown, sometimes the dark green predominates. The body stain is irregularly and slightly gathered into points ; the head mark is generally shewn by a stain shaped like a sector, bounded by two radii from the apex, about 70 apart. The margin is generally broad, occasionally very narrow, bounded inside by a greenish line ; ordinarily tessellated with brown and white, sometimes with green or yellow ; not un- frequently with very slight markings of white, or none at all : in which case the colour is either dark greenish brown, (P. striata, RVC. sp. 69, non Quoy, sp. 58), or with intermediate stages to very light greenish white. That all the shells here classed together belong to the same species, I have not the MAZATLAN UNIVALVES 205 slightest doubt, having carefully examined about 11,000 speci- mens, from which those here enumerated were selected by a carefully repeated process of reduction and comparison. No very young shells were found ; the youngest measuring ' 5 in. in length ; the largest, long. 1*56, lot. 1*33, alt. '39. Hob. Mazatlan ; in extreme profusion ; L'pool fy Havre Coll. Central America, Cuminq, Hinds, Kellatt. ? Panama ; on and under stones at neap tide low water mark, rare ; G. JB. Adams. (A. seruginosa, Mid. non Rve. Conch. Ic. pi. 16, sp. 38) Bodejas, WosnessensJci. (A. striata, Hve.) Gallapagos, Cuming. (A. personoides) Kenai Bay, Wosnessenslci. Tablet 945 contains 28 specimens in the normal state, outside striped, with a prevailing greenish tinge, and regularly tessel- lated margin. 946, 26 sp. do. outside tessellated. 947, 27 sp. do. prevailing brownish tinge ; more often worn outside. 948, 5 sp. the same, tessellated. 949, 12 sp. yellowish ground ; broad streaks of brown. 950, 6 sp. do. narrow streaks. 951, 6 sp. do. scarcely rayed. 952, 12 sp. do. tessellated. 953, 4 do. greenish tinge. 954, 6 sp. border with broad patches of dark, narrow .of light, green inside ; yellow ground. 955, 6 sp. do. light ground. 956, 6 sp. do. tessellated. 957, 6 sp. brownish. 958, 8 sp. broad dark margin, interrupted by narrow light rays ; brownish cast. 959, 10 sp. green cast. 960, 4 sp. light border ; brown, finely rayed with white. 961, 9 sp. do. faintly mottled. 962, 2 sp. do. with purplish tinge. 963, 8 sp. do. with narrow brown dotted edge. 964, 9 sp. do. green tinge, mottled with brown. 965, 4 sp. do. green margin, scarcely tipped with brown. 966, 4 sp. do. very light. 967, 1 sp. do. nearly white. 968, 4 sp. do. with dark brown edge. 969, 8 sp, margin nearly uniform ; dark, with a few white rays. 970, 8 sp. do. scarcely mottled with white. 971, 12 sp. do. lighter tint. 972, 9 sp. margin uniform, ( = P. striata, jun. Rve. not Quo?/,) dark green. 973, 11 sp. do. intermediate. 974, 9 sp. brown. 975, 8 sp. of distorted growth ; of which one has made a series of raised laminse, another a fresh margin greatly con- tracted. 976, 5 sp. shewing the exterior ; tessellated. 677, 7 sp. do. abounding in white. 978, 3 sp. do. striped 979, 4 sp. do. pattern changing. 980, 4 do. dark green var. In all 301 specimens, of which no two are exactly alike. J- 264. ACM^EA FASCICULAKIS, MJce. Zeit.f. Mai. 1851, p. 38, no. 134. f Acmsea mutabilis (pars quidem jun.), Zeit. /. Mai. 1851,. p. 37, no. 133. May 1856. t 206 MAZATLAN UNIVALVES = Patella opea, teste JRve. : nou Nutt., in Rve. Conch. Ic. sp. 79, pi. 29, f. 79, a, b. (Sardwich Isl.) Var.=P. discors, jun. P. P. C. Cat. prim. The following W. Indian species in the Br. Mus. are closely analogous : Lottia lineata, Tranquebarica, and pulcherrima, (Gruilding.) The exquisite beauty of this "most lovely species" (as Menke deservedly calls it), both for the shading of the colours and the delicacy of the penciling, cannot be described. The prevailing tints are a reddish brown outside, more or less mottled or striped with white ; inside a prevailing white, more or less penciled or fretted with brown, and a border, sometimes white with a tessellated penciling of brown ; sometimes a delicate fawn shading into a pinkish or slightly greenish tinge, with or without penciling. The body mark is of a dark lus- trous brown, or very light with a greenish tinge, or nearly absent. It is large for the size of the shell, more or less removed from the margin. The young shells of A. mutabilis, M^ke. are a variety of this species ; which I unfortunately distributed at first as the young of P. discors, with which it has really no connection. The colourless and worn shells of A. mesoleuca and A. fascicularis are very like each other ; but as their general habits are very distinct, it is necessary to keep them apart. In shape, A. fascicularis is much longer, and generally considerably smaller. The standard colour of A. mesoleuca is green, of A. fascicularis red. In A. mesoleuca the markings are laid on with stripes and patches, in A. fasci- cularis with very fine pencilings. In the latter,, the outline of the body mark is much more regularly gathered up into points with concave margins between, the points often making regular lines radiating from the centre. The surface of A. mesoleuca is covered with granulose ribs with smooth interstices and a very thin smooth epidermis ; that of A. fascicularis is very much more finely marked, shewing under the glass smooth ribs with the interstices extremely finely cancellated with very close slightly rugose concentric strise, covered with an extremely thin rather velvety epidermis. The surface of A. fascicularis is much more generally abraded ; and as the young shells were not uncommon in the Spondylus and Chama washings, while not one was found of A. mesoleuca, it is pre- sumed that their station is different. The apex is sometimes brown, sometimes white ; and in the smallest specimen, '035 by '025, shews no trace of being spirally recurved. The young MAZATLAN UNIVALVES 207 shells are known by their finely cancellated texture and deli- cate reddish penciling ; and generally, by a white spot proceed- ing from the apex posteriorly bounded by red lines. In all stages it is thin, and very glossy within. The largest specimen measures long. 1'34, lai. 1'04/aft. *33. Sab. Mazatlan, Menke. Do. ; not uncommon ; L'pool Col. San Diego ; Lieut. Green. Tablet 981 contains 12 specimens, extremely young, whitish. 982, 8 sp. do. reddish. 983, 4 sp. do. much compressed at the sides ; but, as they agree in colour and markings, they are probably only a variety. 984, 5 sp. light margin ; scarcely touched with penciling. 985, 5 sp. do. very slight posterior pencilings. 986, 5 sp. do. margin fawn coloured. 987, 5 sp. do. greenish tinge. 988, 4 do. purplish brown. 989, [5 sp. pencil- ings more distinct. 990, 6 sp. with faint dots all round. 991, 8 sp. do. darker margin. 992, 8 sp. do. still darker. 993, 4 sp. do. very narrow margin. 994, 3 sp. penciling regular ; slight and shaded. 995, 4 sp. do. white border, penciling in single rays. 996, 8 sp. do. penciling fretted, rays distinct. 997, 7 sp. do. margin coloured. 998, 7 sp. penciling interlaced, reddish margin. 999, 7 sp. do. margin dark with penciling. 1000, 9 sp. do.margin very dark, interior white. 1001, 5 sp. do. penciling visible within. 1002, 3 sp. distorted growth. 1003, 6 sp. shewing exterior, rayed. 1004, 4 do. very slightly. 1005, 3 do. uniform red. 1006, 1 do. with light ring. In all 146 specimens, of which no two are exactly alike. 565. ACM^A PATINA, Esch. Eschscholtz Zool. Atl. ed. RathJce, 1831, p. 19, pi. 24, f. 7, 8. Mid. Bui. Ac. St. Pet. vol. vi. no. 20 -.Sib. Reise, p. 187, pi. 16, f. 1 a-d, 2 a-c, 3. + A. scutum, Esch. loc. cit. p. 19, pi. 23, f. 13; teste Mid. loc. cit. et Phil, in Zeit.f. Mai. 18^6, p. 107. ? D'Orb. Voy. Am. Mer. p. 479 (excl. fig.) = Patella mammillata, Nutt. in Jay's Cat. no. 2839 : JRve. Conch. Ic. pi. 42, f. 140, a, b. + Patella tessellata, Nult. in Jays Cat. no. 2885. + Jun. Patella fenestrata, Nutt. in Jays Cat. no. 2815. : JKve. Conch. Ic. pi. 38, f. 121, a, b. + Patella verriculata, Rve. Conch. Ic. pi. 31, f. 87, a, b. + Patella cinis, Eve. Conch. Ic. pi. 24, f. 60, a, b, c. 208 MAZATLAN UNIVALVES ? + Patella Nuttalliana, Rve. Conch. Ic. pi. 30, f. 81, a, b. ? + Patella Cumingii, Rve. Copik. Ic. pi. 16, f. 37, a, 1. (Val- paraiso, Cuming.) ? + Patella diaphana, Nutt. non Rve. (v. supra, p. 203.) =Lottia pintadina, (pars,) Gould, loc. cit. in p. 203. Comp. Patella clypeater, Rve. (as of Less. Voy. Coq. p. 419) Condi. Ic., pi. 16, f. 37, a, b, (Valparaiso, Cuming.) I have the authority of Mr. Nuttall, after a careful collation of his specimens and those of Dr. Gould, for placing together his species above quoted. The ordinary form of the shell greatly resembles A. mesoleuca, but without the green tinge. The pattern, which distinguishes many of the above species, often changes in the same shell. Whether the shells of JS". and S. America are the same, is not yet decided. The extreme form is a large solid white shell, with a broad black rim. To this belong the only two specimens found in the Mazatlan collection. Mr. Heeve, who most obligingly named the Maz- atlan limpets according to his monograph, affiliated these, and some of the dark-margined specimens of A. mesoleuca as their young, to P. striata, Quo?/ fy Gaim. Their species is different ; but the young are most probably his own P. striata, sp. 99, from the G-allapagos. The A. scutum of J?sck. is quite different from the large flat shell with a rich metallic lustre, which often goes by that name in collections ; this occurred in abundance at S. W. Mexico, P. P. C., and is from Monterey, Mus. Cum. The largest Mazatlan specimen measures long. 1*5, lat.V2&, alt. '57. Hab. Sitcha, Eschscholtz, Wosnessenslci. Kenai Bay, do. Aleutian Is., Unalashka, Kastaljskilugvx Bay, Schantar Is., Middendorff California, passim, Nutt all. Monterey, San Diego, Lieut. Green. Mazatlan ; 2 fresh sp. ; L'pool (M (?) Chili, Bolivia, Peru, D'Orligny. Tablet 1007 contains the most characteristic specimen. 266. ACM^A PEESONA, Esch. Zool. Atl. p. 20, pi, 24, f. 1, 2. Mid. Hal. Ros. pt. ii. p. 36, pi. 1, f. 3. + Jun.=A. radiata, Esch. loc. cit.. p. 20, no. 8, (teste Mid.*) + A. ancylus, Esch. loc. cit. p. 20, no. 10, pi. 24, f. 4 bis, 6. (do.) * Philippi however (loc. cit. supra) regards A. radiata and A. ancylus as forming a different species not from .N". America, but from Chili. MAZATLAN UNIVALVES 209 = A. scutum D'Orb. loc. cit. pi. 64, f. 810, excl. diagn. (teste Mid.) ? = Lottia punctata, Gray ; (non Quoy fy G-aim.) teste Mid. = P. Oregona, Nutt. in Jay's Cat. no. 2852: Jtve. Concfi. Ic. pi. 36, f. 112, a, b. + P. umbonata, Nutt. loc. cit. no. 2887 :Rve. loc. cit. pi. 35, f. 107, ab. + P. pileata, Nutt. loc. cit. no. 2861. This species is known by its comparatively small size, com- pressed sides, and recurved apex. The front part is sometimes covered with stout, rounded ribs, sometimes with a very few fine and separate ones, and sometimes nearly smooth. It is either uniform in tint, or is minutely spotted outside ; inside white and blackish brown. The solitary Mazatlan specimen has broad, rounded ribs, and a somewhat shagreened surface ; and measures long. '96, lat. "8, alt. '42. /Za&. Sitcha, Esclisclioltz . Mouth of Columbia Eiver, Nut- tall. Sta Barbara, Col. Jeivett. San Diego, Lieut. Green. Mazatlau ; 1 fresh sp. ; L'pool Col. Tablet 1008 contains the specimen. 267. ACMJ^A SCABKA, Nutt. Jays Cat. no. 2907. .R-w?. Conch. Ic. sp. 119, pi. 37, f. 119, a, b. TsTon Patella (Lottia) scabra Gould Exp. Shells, p. 10 : = Patella spectrum, Nutt. in Jay's Cat. no. 2877 : Rve. loc. cit. pi. 29, f. 76, a, b. Although the name of Gould was published with description before that of Nuttall, yet I have presumed upon the known courtesy of Dr. Gould, in order to avoid re-naming a species which has been widely distributed in collections, and which (as well as Dr. Gould's A. scabra, under the name of P. spec- trum) has been figured in the Conch. Ic. This shell occurred un- named in Dr. Gould's collections. It frequents the temperate portion of the coast, and is easily recognized by its light flesh colour, and tubercular rasp-like surface. Long. 1'06, lat. "9, alt. -4. ffab. California, Nuttall. Monterey and Sta Barbara, Col. Jewett Mazatlan ; 1 sp. only ; L'pool Col.$. W. Mexico ; 1 sp. P. P. C. Tablet 1009 contains the specimen. 210 MAZATLAST UNIVALVES -^ 268. Ac JOE A MITELLA, MenJce. Zeit.f. Mai. 1847, p. 187, no. 43. *= Patella navicula, Rve. Conch. Ic. sp. 130, pi. 4), f. 130, a, 6. This shell having been first named from a single worn speci- men, the minute details of Menke are not generally applicable. The description in the Conch. Ic. applies to a larger number, but not to the whole. Shell small, strong, conical, almost exactly resembling a common Barbadoes species (? = P.. leuco- pleura, B. M. Cat. Sagr. Cub. Moll. p. 34, no. 404) ; outside either very finely or coarsely ribbed, with or without granules, generally eroded or encrusted ; inside white, blackish brown, tortoiseshell or light chesnut, often with a greenish tinge ; margin generally with a row of black dots, more or less con- spicuously connected with the apex (especially in young shells), sometimes coalescing into a black rim, rarely wholly absent. Margin sometimes finely crenulated by the projecting ribs, sometimes almost entire. Animal mark irregularly and slightly gathered up into points. It either excavates a hollow for itself on other shells, or keeps its ground clear while the coralline grows up round it. Its small size and shape are not the result of the accidents of its position,* as it is generally found where it has plenty of room to grow larger if it chooses. The smallest specimen measures long. '05, lat. '03, alt. 'Q15. Aflat '48, '35, '17. A conical i9 '51, '3), *34 Hob. Mazatlan, Lieut. Shipley, Mus. Cum. : do. Melchers, 'Menke : do, ; not uncommon ; L'pool Col. Tablet 1010 contains 5 specimens very young. 1011, 17 young shells, each varying in colour, &c. 1012, 30 specimens, of which, no 1 two are coloured exactly alike. 1013, 4 specimens shewing external variations. 1014, a specimen in situ on Pissurella ; also Patella discors with attachment marks. 1015, a gigantic specimen, if of this species as is probable, measuring long. '93, lat. '71, alt. '41. GENUS SCUTELLINA, Gray. Scutellina, Proc. Zool. Soc. 1847, p. 168, no. 405. Scutella, pars, rod. Proc. Zool. Soc. 1834, p. 47 : non Lam. Patella, pars, auct. * Dr. Gray, when first examining this collection, expressed the opinion that P. Mexicana, P. discors, A. mesoleuca, A. fascicularis and A, mitella, might bo varieties of the same species, according to station, food, &c. MAZATLAN UNIVALVES 211 ?Pars = Pilidium, Forbes fy Hani. = Jothia, Phil. Handb. Conch. p. 200 :=Iotliia, Gray in Mrs. Grays Fig. Moll. An. p. 93 : S. & A. Ad. Gen. vol. i. p. 461 : n'on Forbes, Athen. 1849, (=Lottia, err. typ.) teste Woodw. This genus is a part of the Scutella of BrocL (the remainder constituting the genus Broderipia, Gray, of the family Stoma- tellinse,) of which the name was altered to Scutellina by Dr. Gray in consequence of its preoccupation by Lam. for a genus of Echinoderms. 269. SCCJTELLINA STAVICELLOIDES, n. S. S. t. oblong a, lateribus subplanatis, valde incequilaterali ; apice terminally sed a margins remoto ; tenui, subdiapJiana* albidd, epidermide tenuissima cinerea induta ; liris exillimis radiantibus et concent rids, subcequalibus, creberrimis > confertim decussata, ad intersectiones subnodosis ; interstitiis guadratis ; margine a liris radiantibus vix crenulato ; columelld (ut in "Navicelld"} pianola, arcuala. One specimen only of this beautiful and very distinct species was found by Mr. Darbishire : the apex was unfortunately broken, in detaching the shell from extraneous matter, but its place is nearly determined by the sculpture. The margin is concave ; the shell resting on its anterior and posterior ex- tremities. Long. '22, lal. "14, alt. "06. Hab. Mazatlan ; 1 fresh sp. from burrow of Lithodomus, in Spondylus calcifer ; Upool Col. Tablet 1016 contains the specimen, presented by B. D. Dar- bishire, Esq. FAMILY GADIJSTIAD^E. This family was placed among the Pulmobranchiata, next to Siphonariada?, when the animal was only known by Adanson's notice, Gray, 1847 : in the same company, between Ca3cum and Acmsea, by Philippi, 1853 : next the Patellida3, after Philippi had published a description of the animal, by Gray, 1850, and H. fy A. Adams, 1854. The animal is gill-bearing, while that of Siphonaria is pulmonated. The shell has no interruption in the muscular scar for the slit, which is at the left of the head, and generally very small. 212 MAZATLAN UNIVALVES GENUS GADINIA, Gray. Phil. Mag. & Journ. 1824, p. 63: Phil. Handb. Conch. p. 199. H. $ A. Ad. Gen. vol. i. p. 463. Mouretia, Sow. Proc. Zool. Soc. 1835, p. 6 iZool. Beech. Toy. p. 147. Pileopsis and Patella, sp. auct. 270. GADINIA PENTEGONIOSTOMA, Sow. 6r. t.plus minusve conicd, seu valde depressd, albd; subcirculari 9 sew irregulariter varie angulata ; apice subcentrali, in adultfi, detrito, injuniore spirali, anfractibus planorbifonnibus, adver- sum cervicem later aliter affixo ; costis plurimis radiantibus, angustis, rotundatis, v aide ext ant ibus, inter stitiis subcequantibus ; margine costis productis, cavatis, subdiaphanis ; canali minima, ad marginem haud extante ; cicatrice musculari dextrorsum integro, sinistrorsum irregulariter lobato. Animal cavitatem corrodente. Siphonaria pentegoniostoma, Sow. ? ubi. Having met with no description of this shell, the name of which is likely to mislead, I have drawn out a diagnosis from a comparison of several hundred specimens. Most of the shells are very irregular in growth, apparently crowding each other and forcing their bodies into angular shapes : but the normal condition appears to be nearly round, with semi-transparent, hollowed, projecting ribs. The muscular scar, on the opposite side from the slit, is irregularly divided into lobes. The mus- cle of attachment appears very strong, the shell being generally broken in removal; and on the place of adhesion (which is eaten away) is generally seen a black circular ring. JS"o very young specimens were found, to compare with tlfose of Siphon- aria: but on the smallest, '23 in length, is just discernible a . small planorbiform apex, turned to one side, away from the head ; in this respect agreeing with Siphonaria and differing from Patella. The ribs are of nearly equal size, there being no large one to receive the canal, as in Siphonaria. The shell often begins very conical, and suddenly becomes flat. A regularly grownup sp. measures long. *68, lat. '63, alt. '18. The largest sp. \ ' '98, '88, '43. A flattened sp. '67, '53, '16, MAZATLAN UNIVALVES 213 Hob. Mazatlan ; gregarious, often adhering to each other, not common ; L'pool CoL Tablet 1017 contains 3 sp. finely grown. 1018, 3 do. usual state. 1019, 3 do. irregularly grown. 1020, 6 sp. ; one with 5 corners, another with 4, another with 3, another with 2, another with 1, the other circular. 1021, 2 sp. very deformed growth. 1022, 2 do., one with double margin, the other ex- tremely depressed. 1023, 1 sp. with dead Balani, enclosing a Crustacean. FAMILY FISSUEELLID^E, GENUS FISSUBELLA, Brug. The Mazatlan Fissurellse naturally divide themselves into two sections ; the first with the surface irregular, and the margin not crenulated except by the projecting ribs ; the second with the surface cancellated, the margin crenulated, the apex in the young shell prominent and recurved, the callus frequently truncated, sometimes laminated. In the first, the Bimuloid stage must be of very short duration, as extremely young shells were found, of the same form as the adult : in the second, this stage continues for a comparatively long period, as may be observed in the English species, as well as in the specimens here recorded. To the latter group H. & A. Adams (Gen. i. 447) have unfortunately given the name of Lucapina, as of Gray. The animal however of Gray's typical species, L. crenulata (Fig. Moll. An. p. 92, no. 159), is described by Nuttall as like that of Parmaphorus, extremely large, and completely enveloping the shell. The shape and markings, which in most species are tolerably constant, are in others very variable : even the form of the aperture and callus is in some instances remarkably changeable. SECTION A. Margin interrupted ly ribs. \ 271. FlSSURELLA VIEESCENS, Sow. -r Proc. ZooL Soc. 1834, p. 125. Mull. Syn. Nov. Test. Viv. p. 154. Sow. Condi. III. sp. 31, f. 37 (quasi F. coarctata, Klng.)Rve. Condi. Ic. pi. 4, f. 12, sp. 12. Wee. Zeit. f. Mai. 1851, p. 36, no. 130. C. B. Ad. Pan.. Shells, p. 238, no. 361. H. & A. Ad. Gen. i. 446. 214 MAZATLAK UNIVALVES This species scarcely differs from F. nigropnnctata, Sow, except in the entire absence of clack dots round the margin. Shell with very numerous fine ribs, with still finer ones between, sometimes slightly nodulous. Outline more or less oval, more or less conic ; growth regular. Hole large, subcentral, deeply chiseled, oval, constricted in the middle externally, where it is bilobed. Colour olive green, often stained with red when polished. Surface frequently eroded. Interior from pale to dart green ; margin crenated by the ribs ; callus rather thick, radiately corrugated, not bounded by a dark line. Muscular impression distinct. The young shells (which were very rare) are shaped like the adult, with the hole even larger in propor- tion. The largest sp. measures long. 2 '2, lat. 1*66, alt. *8. An elongated sp. 1*7, , 1'22, , "65. A flattened sp. A rounded sp. A conical sp. The smallest sp. 1'95, 175, 175, 8, 1'48, 1-49, 1'34, 56, 62. 67. 77. 2, with a hole '13 by '08. Div. 100 120. Hob. Panama ; in exposed situations at low water ; Cuming. Do. ; common, on a ledge of rather smooth rocks, between half tide and low water mark, in a place somewhat exposed to the sea ; C. IB. Adams. Mazatlan ; very common ; I/pool Col. Tablet 1024 contains 10 sp., various ages, normal state, 1025, 4 do., elongated form. 1026, 4 do. flattened form. 1027, 3 do. rounded form. 1028, 2 do. conical. 1029, 2 do. ribs strong. 1030, 2 do. ribs faint. Tablet 1031 contains 2 sp. surface cleaned, shewing red tint beneath. 1032, 5 sp. shewing shades of colour within. 1033, 2 sp. diseased from worms, &c. 1034, 1 sp. hole irregular through accidental breakage. Tablet 1035 contains a remarkable monstrosity* with 2 holes. The first is in all respects normal. The second is adjacent anteriorly, perfectly round, with a thick callus within, united to that of the normal hole posteriorly, anteriorly rather pointed.* * A similar monstrosity appears in a specimen of F. ornata in Mr. NuttalTs collection. The shell is abnormally conical, with the hole nearly round instead of oblong, bilobed. The second hole commences 3-5ths down towards the anterior margin, is very minute, and finds its exit close to the other at the apex. It is surrounded by a thick callus. A still more remarkable monstrosity, without a hole at all, exists in D'Orbigny's Col. v. . M. Cat, D'Oi-b. Moll. p. 61, no. 435. MAZATLAN UNIVALVES 215 Tablet 1036 contains a sp. with the hole not constricted in the middle. Tablet 1037 contains a sp. with a circular hole. Nodulous ribs strong. Inside white within the muscular scar, and at the margin. In other respects like the typical form. It would have passed for a distinct species, but for the intermediate form quoted above ; and closely resembles F. Barbadensis. [272. FISSTJEELLA BAEBADENSIS, Gmel. Patella Barbadensis, Gmel. p. 3729, no." 199 : + P. perforata, Gmel. p. 3730, no. 202 : +P. porphyrozonias, Gmel. p. 3730 ; Dillw. p. 1061, no. 102 : + P. rosea, Gmel. p. 3730 ; teste B. M. Cat. Cub. Moll. p. 33, no. 400. Patella perforata, Dillw. Descr. Cat. p. 155.8, no. 95. Fissurella Barbadensis, Lam. An. s. Vert. vol. vii. p. 595, no. 9 : et auct. Cremides Barbadensis, H. A. Ad. Gen. i. 446. One small specimen of this well known West Indian species was found, which might have been taken for an extreme variety of F. rugosa, were it not for an abundance of the Spiroglyphus, and a trace of the red coral, both of which are characteristic of the Atlantic ocean, and are entirely absent from the genuine Mazatlan shells. It is perfectly fresh, and probably came over on a pebble as ballast. Hob. Cuba, Sagra. Barbadoes, Lamarck, et auct. Mazatlan; 1 small specimen, ? imported in ballast ; L'pool Col. Tablet 1038 contains the specimen.] I 273. FISSUEELLA EUGOSA, Sow. F. t. maxime variante ; plerumque costis plus minusve ceguaU- bus, interdum nodulosis, interdum quibusdam alteras maxime superantibus ; margine valde irregulari, interdum ovali, inter- dum elongato, plerumque ant ice angulato, a costis plus minusve crenato ; aperturd haud centrali ; sen subcirculari^ ovatd ; seu oblongd, media constrictd; seu bilobatd; seu trilobatd; seu lineari, ad extremitates lobatd : callositate plus minusve extante, seu concolore, seu lined purpured cinctd ; superficie externd rubro- olivaced, sen rubrd, seu cinered ; internd virescente, interdum rubro plus minusve maculatd ; formd plerumque planatd, inter- dum subconicd. Conch. III. sp. 66, f. 54>.Itve. Conch, Icon. pL 8, f. 56. (Diagn. auct.) 216 MAZATLAN UNIVALVES Cremides rugosa, H. 8f A. Ad. Gen. i. 446. + Fissurella chlorotrema, MJce. Zeit.f. Hal 1847, p. 186, no. 40. Fissurella humilis, MJce. loc. cit. no. 41. ? + F. viminea, MJce. Zeit.f. Mai. 1851, p. 36, no. 131 (non Rve.J = Fissurella virescens, jun. P. P. C. Cat. Prov. It is not to be wondered at that Menke did not find any figure in the Conch. III. answering to his shells ; as the species was described from not very characteristic specimens of a rare and extreme form of this very variable shell. Although placed by H. & A. Ad. in a different subgenus from F. virescens, some forms run so closely into the young of that species, that it was only after repeated examinations of some thousands of specimens, and the fortunate discovery of a very few of the real F. virescens, jun. that I felt justified in separating them. The chief differences are, (1) that F. virescens is of a very regular, F. rugosa very irregular habit of growth : (2) that F. rugosa is much smaller, and never has the hole central, though the amount of inequality is very variable : (3) that the hole of F. virescens is always much larger in proportion. The station also appears different, as F. rugosa is very fre- quently entirely covered with algse, and seldom rubbed ; while F. virescens is generally rubbed ; and only one (doubtful) speci- men was found with algae. In the ordinary growth of the shell, the ribs are not much more unequal than in F. virescens. The most remarkable feature in the species is the great variation in the shape of the hole ; in this respect resembling F. ornata, Nutt. and F. macro trema, Soio. The extreme forms however pass into each other by such insensible gradations, that it is scarcely possible to regard them as otherwise than one species. The youngest specimen, though only '035 in length, with a well formed suboval hole, has no spiral vertex ; there is however a scar where it may have adhered.* In a larger specimen, ' 11 in length, the shell is formed as in the adult, light red, with an oval hole. The largest specimen measures long. 1*45, tat. '97, alt. 28. A broad specimen 1*18, "87, '34. A conical specimen *92, '62, *3- A flat sp. (shape resembling Clypidella) '74, '53, 'II. An elongated sp. T03, *56> "24. Holes, '08 by '06 ; 13 by '04. Div. 130 160. * If furthfer investigation should prove that the apex of these species is decidu- ous, while in the next section it is persistent until it becomes absorbed in the progress of the hole, it will form a remarkable character of separation between the groups. MAZATLAN UNIVALVES 217 ffab Gallapagos Is., C timing. Mazatlan ; not uncommon, frequently growing on uneven surfaces, and often covered with algse ; L'pool Col. Tablet 1039 contains the two youngest specimens. Tablet 1040 contains 3 sp. smooth growth, hole oval. 1041, 3 do. regular form, hole with medial constriction. 1042, 3 do. elongated growth. 1043, 2 do. hole trilobed. 1044, 1 do. hole elongated, lobed at each end. Tablet 1045 contains 3 sp. rough growth, hole rounded oval. 1046, 3 do. hole elongated oval. 1047, 3 do. with medial con- striction. 1048, 4 do. hole elongated, obscurely trilobed. 1049, 5 do. hol6 sub-linear, lobed in the middle. Tablet 1050 contains 5 sp. ribs varying from fine and equal to very coarse and unequal. 1051, 3 sp. red colour developed outside. 1052, 7 sp. with more or less of red stains within. 1053, 2 sp. dark line round callus well developed. 1054, 2 sp. elevated growth. 1055, 1 sp. with two large perforations (made by PLithophagi.) 274. FlSSUEELLA NIGEOCINCTA, n. S. " F. t. ovali, latd, conicd ; albd, lineis nigris radiantibus eleganter picld ; striis radiantibus tenue ccelata ; aperturd subcentrali, obscure trilobatd ; intus albd, margins tenue crenu- lato, denticulis nigris ; callosilate alba, lined nigrd cinctd." "Differs from the young of F. alba in its greater breadth, less compressed growth, finer striae and crenulations ; from F. nigropunctata, in the black line round the callosity ; and from both in the form of the hole, which is trilobed, not contracted in the middle. L/ong. '75, lat. '52, alt. "3." Proc. ZooL Soc. Dec. 1855. Hab. Mazatlan, Mus. Gaming. ?Do. ; extremely rare, on Spondylus calcifer ; ISpool Col. Tablet 1058 contains one of two very young specimens '07 in length, which may belong to the above species, described from specimens in the Cumingian Collection. Although so small, it displays no trace of spiral vertex. Shell white, with black stripes. Hole suboval : this may be a character of youth. 275. FISSUEELLA , sp. ind. Shell elongated, conic, much compressed ; ribbed as in F. virescens, &c. ; anterior side shortened ; hole long, narrow, trilobed ; colour green witjiin, nigropunctate at the margin ; May 1856. v 218 MAZATLAN UNIVALVES callus white, corrugated, not bordered. Differs from F. nigro- punctata in the shape of the hole ; from F. virescens in this and in the nigropunctation ; from F. alba in both characters, in the green colour, and in the still more compressed growth as compared with that species ; from F. nigrocincta, in the green colour and absence of black ring ; from the conical variety of F. rugosa in the regular growth, and nigropuncta- tion, which is never seen in that variable species. The outside not being in good condition, and the young of some of the above species not having been observed, it is not thought prudent to name it. Long. *55, lat. '36, alt. '2. div. 90 by 85. JIab. Mazatlan ; 1 sp. only ; JL'pool Col. Tablet 1057 contains the specimen. 276. FlSSUEELLA ALBA, n. ,9. F. t. oblongd, compressd, conicd, regulari, antice curtiori ; albd, rarius nigro radiatd ; liris radiantibus, subcequalibus, interdum Icevioribus, inter dumvalidis, valde nodulosis ; nperturd majore, oblongd, in medio constrictd, parietibus solidis, scepius in medio elevatis ; intus albd, seu pallidissime earned, rarissime vix viridi tinctd, nitente, scepius annulo nigro callositatem oblongam circumeunte, margine secundum liras crenulato, in testa juniore s&pe nigropunctatd. Jun. ? = F. gemmata, Mice. Zeit.f. Mai. 1837, p. 186, no. 42. This well marked species is easily recognized by its elongated, compressed, conical and regular growth. The young shell is often rayed outside, and dotted in the inner margin with black : else it is of a French white, or very pale flesh colour, glossy inside : rarely with a slight greenish tinge near the callus. The ribs are generally rather fine and irregularly tuberculous ; sometimes strong and nodulous ; very rarely slender and almost smooth. The black band round the callus is usual, but not constant. The F. gemmata of Mke., described from a single small shell, is probably a rubbed young specimen of this species ; but the diagnosis does not accord with sufficient accuracy to adopt his name. The shells are generally more or less incrusted with coralline, which often grows in irregular longitudinal rays, occasionally meeting over the centre of the hole, which they thus render bipartite. The aperture is large and long ; its walls constricted in the middle and at the same place elevated on each side. The smallest shell found, in MAZATLAN UNIVALVES 219 which the hole preserves the normal characters, measures long. '48, lot. '3, alt. '15. The largest sp. (elongated) ;1'67, 1*06, '6. A normal sp. 1'56, 1'08, '62. A conical sp. 1*34, *96, *62. Hole of largest sp. '3 by '12. Div. 95 by 105. Hob. Mazatlan ; common ; L'pool Col. Tablet 1058 contains 8 sp. different ages, normal state. -1059, 3 sp. elongated. 1060, 3 do. smooth. 1061, 3 do. elevated, nodulous. 1062, 4 sp. shewing interior. 1063, 3 sp. with singu- lar growth of coralline. 1064, 1 do. smooth, with Acmaea mitella in situ. 1065, 1 do. nodulous, with dried animal of adherent limpet. 2066, 2 sp. hole abnormally produced, (div. 85.) 1067, 3 sp. withBalani, and attachments of limpets. In one (empty), a young Isognomon has taken up its abode. Another (spinous) has inserted a fang through the hole of the shell. 1068, 3 sp. distorted growth. SECTION B. Margin smooth. 277. FlSSTJBELLA PERTJVIANA, Lam. Lam. An. s. Vert. vol. vii. p. 599, no. 17. J?. M. Cat. D'Orb. Moll. p. 51, no. 432. + Fissurella subrotundata, Desk. JEW. Meth. Vers, vol. ii. p. 135, no. 11 1 Lam. An. s. Vert, vol vii. p. 602, no. 26. Var. = Fissurella affinis, Gray, Proc. Zool. Soc. 1834, p. 125. Sow. Conch. HI. p. 4, no. 35, f. 44. Cremides Peruviana, H. fy A. Ad. Gen. i. 446. Only one specimen, and that somewhat worm-eaten, was found of this characteristic S. American shell. * Shell very conic, slightly ribbed, hole nearly round, anterior side pointed, inside white, with a sharp, non-crenated, narrow margin, shaded with purplish brown. Long. 1*35, lat. 1'12, alt. *68. Hob. Peru, jHumboldt fy Bonpland. Is. Mexillones, Lobos; Iquiqui and Valparaiso ; Cuming. Mazatlan ; 1 specimen ; L'pool Col. Tablet 1069 contains the specimen. 278. FlSSURELLA SPONGIOSA, n. S. F. t. elongatd, compressd, conicd, antice angiwtiore, postice ' dilatata ; superficie externd quasi spongiosd, nee liratd nee striatd ; viridi, juniore lineis, advltd maculis castaneis radi- 220 MAZATLAN UNIVALVES antibus pictd ; aperturd elongatd, obscure trilobatd ; pagind internd nitente, cinereo-albidd, inaculis externis plus minusve monstr antibus, callositate marginem versus rubro-purpureo : cicatrice musculari irregulari, intus callosd, antice punctulatd ; margine acuto, haud crenulato, testa juniore castaneo punctato. Only two specimens were found of this singular little shell ; the younger one of which, though the most highly coloured, is diseased within, and displays neither the lurid colour of the faecal callus, nor the punctures on the anterior part of the general callosity which fills up the space between the irregularly jagged muscular scar and the region of the hole. It most resembles F. catillus, IRve. The external surface is loose and rough. Long. '7, lat. antice '3, postice '43, alt. '24, dtv.105 by 80. Hole '14 by "04. Hob. Mazatlan ; extremely rare ; IS pool Col. Tablet 1070 contains the larger specimen. SUBGENUS GLYPHIS. Animal margine palliijimbriatd, marginem lestce superante. Testa superficie cancellatd, margine crenulato, callositate s&pe truncatd, interdum laminatd ; testa juniore Hirnul&formi, spird in aperturd crescente absorptd. Lucapina, IT. 8f A. Ad. Gen. i. 447, (maxima pars) : non Gray. 279. GLYPHIS IN^EQUALIS, Sow. Fissurella insequalis, Sow. Proc. Zool. Soc. 1834, p. 126 : - Conch, III. no. 36, f. 45. Eve. ConcL Ic. pi. 7, sp. 50. Lucapina insequalis, H. fy A. Ad. Gen. i. 447. + Fissurella pica, Sow. Proc. Zool. Soc. loc. cit: Conch. HI. no. 37, f. 32, et var. f. 33. Rve. Co%ch. Ic. snbglobosd, subdepressd, tenui, subdiapkand ; suturd im pt*essd ; umbilico hand magno ; regione umbilicali magnd, concavd, radiatim rugosd ; anf . ult. carinulis v. haud promin- entibus, quarum duce infra et supra peripheriam haud planatam site sunt, dues in spird haud planatd, alter a regionem umbili- ealem describens ; sulcis spiralibus in basim, carinulis simu- loMtibus ; aperturd subelongatd, ad basim angulatd, avfr. penult, pa-rum attingente. Known from V. cincta by the non-prominence of the keels, rounding and keeling of the spire, and greater elevation. The only specimen found is not mature, scarcely a whirl being formed of the adult portion. Long. '22, lot. '03 by '023. div. circ. '165. Hal). Mazatlan ; 1 sp. off. Spondylus ; Upool Col. Tablet 1160 contains the specimen. 310. PVlTEINELLA NATICOIDES, n. S. ? V. t. subglobosd, subdepressd, nitidd, subdiapkand, albd ; anfractibus iv. et triente, quarum primi convexiusculi sunt, ultimi sutura, vix impressd ; striulis incrementi exillimis, max- ime suturam versus, haud conspicuis ; umbilico prof undo, an- gusto, a carind extante callosd definitd ; aperturd anfr. penult, parum attingente, labio subexpanso, a carind angulato. This curious shell might be either called by the above name or Natica vitrinelloides, as it partakes of the characters of both genera ; though the texture and difference of convexity in the first three whirls incline the balance in favour of the former genus. Thus the shell alone cannot decide between animals widely removed. It looks like a flattened, white, glossy Natica, with the straight umbilicus bounded by a con- spicuous keel which runs into the aperture. Long. '03, lat. .047 by '04, div\ 160. Hab. Mazatlan; 2 sp. off Spondylus & Chamar ; L'pool Col. Tablet 1161 contains the largest specimen. 311. PYlTEINELLA PLANOSPIEATA, n. S. ?V. t. magnd (quoad genus), tenuissimd, subdiaphand, albd; spird planatd, ad carinas valde angulatd, spiraliter striatd ; ad basim tumente, convexd, profunde sed ncn late umbilicatd ,- MAZATLAN UNIVALVES 247 basi et uinbilico spiraliter liratis ; ad peripheriam carind acutd, prominente, alterd spiram ascendente, minus prominente ; inter eas suturd valde impressd ; aperturd anfr. penult, vix ad cari- nam attingente. This very remarkable shell has the general appearance of Helix (Iberus) G-ualterianus. It has however two keels, (that on the spire being less prominent) and a deep rather narrow umbilicus. The whirls rapidly increase in size both in breadth and thickness. The generic position is doubtful, the only specimen found having lost the greater portion of the last whirl. The general aspect and texture are like a very large Vitrinella, and the usual unformed portion is clearly denned, being much larger than in the typical species ; it differs how- ever in the comparative length of the adult part, which must have consisted of at least two complete whirls. The shell when perfect may have been "2 in length: the penultimate whirl measures long. '03, lat. "04 by "025, div. 180. Hob Mazatian ; 1 broken specimen off Spondylus calcifer ; Upool Col. Tablet 1162 contains the specimen. 312. ? VITRINELLA OKBIS, n. s. ? V. t. discoided, diaphand, hyalind ; valde complanatd, spird planatd, basi subplanatd ; ad peripheriam rotundatam, et intus umbilicum apertissimum, striis spiralibus paucis, plus minusve impresses ; infra et supra Icevi, interdum, stria spirali juxta suturam Jiaud impressam ; anfractu ultimo penultimum parum attingente ; aperturd angustd, spiraliter elongatd, sub- guadratd ; labro sinuato, posticc producto. This singular species has relationship to Discohelix, Dlcr. Palceont. i. 132, = Orbis, Lea; of which, as of Vitrinella, the animal is unknown, being classed with Littorinidae by Phil. Handb. Conch, p. 174, but with Architectonicidas by H. fy A. Ad. Gen. i. 211. It has the appearance of the common flat Dundry Ammonites, with the periphery rounded and spirally striated. A beautifully perfect specimen, quite transparent, but probably immature, was found inhabiting the spiral portion of a dead Isapis maculosa, the mouth of which had been choked up with coralline, among the debris of a Spondylus. It measures long. '0075, lat. '033 by "027, div. 180. Three other broken specimens were found on Chamse. 248 MAZATLAN UNIVALVES Hal. Mazatlan ; extremely rare, on Chama and Spondylus ; L'pool Col. Tablet 1163 contains the perfect specimen. GENUS PLIOTIA, Gray, Syn. B. M. 1840. JET. Sf A. Ad. Gen. vol. i. p. 404. Phil. Handb. Conch, p. 206. Delphinula, pars, auct. The following shells are ranked doubtfully with this genus, not having the expanded lip of the typical species, and the opercula being unknown. 313. P LlOTIA CAEINATA, n. S. ?L. t. solidd, cinered, rufo tinctd ; spird depressd, anfractibus iv. supra subplanatis, suturd distinctd, angulatd ; carinis iv. extantibus circa peripJieriam ; liris spiralibus iii. in spird, nodulosis ; iii. in basi rotundatd, Jiaud extantibus ; circa um- bilicum magnum radiatim rugoso-nodosd ; aperturd intus circu- lari, anfr. penult, parum attingente ; anfractu ultimo valde decumbente. Shell comparatively solid and opaque ; it may be young, but from the small size of the nuclear portion and the sudden declension of the last whirl, it is presumed to be nearly mature. Long. '03, lat. '045 by '04, div. (anfr. penult.) 175. Hob. Mazatlan ; 1 sp- on Spondylus ; L'pool Col. Tablet 1164 contains the specimen, 314. PLlOTIA STEIULATA, n. S. ?L. t. turbiniformi, spird subelevatd, albidd, solidd ; anfracti- bus iii. rotundalis, radiatim exillime et confertissime striulatis, carinis parum extantibus iii. spiralibus ; umbttico magno ; in basi interdum rugis radiantibus ; aperturd declivi, solidissimd, intus rotundatd, anfr. penult, parum attingente. The thickness of this little shell is extraordinary, being at the posterior portion of the aperture nearly '005 in. The whirls are rounded, obscurely carinated, and most minutely and closely striated in the direction of growth. Long. '027, lat. '037 by '03, div. 130. MAZATLAN UNIVALVES 249 Sab. Mazatlan ; 1 sp. off Spondylus ; Lpool Col. Tablet 1165 contains the specimen. 315. ?? LIOTIA C-B-ADAMsn, n. s. ?? L. t. tenuissimdj diaphand, albd ; turritd, anfractibus iii. tumentibus, sup erne sub angulatis ; liris radiantibus (inanfr.ult. xxiij a lirulis spiralibus circiter viii. nodulosis clegantissime cancellatis ; anfr. primo et dimidio Icevibus, tumentibus ; liris radiantibus in basi evanescentibus ; umbilico parvo ; aperturd subcirculari, peritremati continue, ab anfr. penult, vix inter - rupto. Although this is clearly a young shell, its characters are so well marked and distinct from any other known Mazatlan species, that it has been thought best to preserve a remem- brance of its beauty in connexion with the name of the most accurate and deeply lamented Prof. C. B. Adams. It has the texture of Vitrinella, but is distinguished by its turrited form, and by the large size and short length of its apical portion, which occupies a whirl and a half, instead of three minute whirls as is customary in that genus. The rest of the shell is beautifully decussated by radiating lirse, obsolete on the base, knotted by revolving lirulse, three of which appear on the base. Both labrum and labium are extremely thin. It may possibly belong to Rissoidae. Long. '024, lat. '022, div. 70. Hob. Mazatlan ; 1 young sp. off Spondylus ; L'pool Col. Tablet 1166 contains the specimen. 316. ? LIOTIA , sp. ind. Tablet 1167 contains a fragment of a somewhat elevated shell, with the apex flattened. The first whirl is large and smooth as in PPL. C-B-Adamsii ; but the sculpture is extremely strong, with stout transverse tubercular ridges and spiral decussating lirse. It is distinguished from Chrysallida by the flat, dextral apex. JIab. Mazatlan ; 1 sp. off Spondjdus : L'pool Col. 250 MAZATLAN UNIVALVES GEips GLOBULUS, Schum. Schumacher, Essai <$fc. 1817, no. 23 : (non Soiv.). Phil. Handb. Condi, p. 208. Ttotella, Lam. 1822, et auct. Umbonium, Link; A. Ad. Mon. in Proc. Zool. Soc. 1853, p. 187 : H. $ A. Ad. Gen. vol. i. p. 407. Pitonellus, Montf. Helicina, (Lam. a" prima manu) Gray in Proc. Zool. Soc. 1847, p. 145. 317. ? GLOBULUS TUMENS, n. s. ? G. t. globosd, solidiusculd, alba, subnitente ; spird planatd, depressd, anfractibus iv. suturd hand impressd ; striulis spira- libus subobsoletis teiiuissime ornatd ; callositate valde tumente, trientem partem basis tegente, suturd impressd, -mnbilicum tegente, in parietem et inius suturam spiralem ascendente, juxta labium vix planatum ; aperturd intus rotundatd, labro in spiram ascendente. This species is intermediate between the typical Globnli and the Ethalioe. In the faint sculpture and slight planing off of the callosity, it presents the characters of the latter genus ; in the large swelling growth of the callus, which appears glossy over the whole surface, and covers the body whirl within the mouth, running up to the suture, it is a true Globulus. Two older specimens were found, sufficiently agreeing in other respects, but displaying a groove in the callus near the base of the columella, exactly in the same place, which is remarkable if accidental. They are both however worn specimens. If it should prove a constant character, they may take the name of "G. sulcatus, t. callo basim versus subprofunde sulcato." Long. '013, tot. "038 by '033, div. 160. Hal). Mazatlan ; 3 sp. off Chama and Spondylus ; L'pool Col. Tablet 1168 contains the fresh specimen, andjone of the form G. sulcatus. SUBGENUS ETHALIA, H. fy A. Ad. Gen, vol. i. p. 409 : Proc. Zool. Soc. 1853 (Mon. Umb.) p. 189. A small group of Mazatlan shells, of the general aspect of Vitrinellee, and agreeing with Globulus in having a callous base, MAZATLAN UNIVALVES 251 differ from the typical species of that genus (1) in being fre- quently sculptured, (2) in the callus winding round, generally not covering the umbilicus, (3) in the outside of the callus not being glossy, but having a glossy portion scooped out near the columella. The labium is generally not reflected over the body whirl. They appear to retain permanently the young state of Teinostoma. At the same time, the specimens examin- ed were so few (only 9 of 5 species) and some of these were to such an extent intermediate between other groups, that it is impossible to designate them with confidence. Some of the small white shells described as E-otellse are probably referable to this form. Mr. Cuming states that the species he found were deep water shells, while the true Globuli are littoral. 318. ETHALIA PYRICALLOSA, n. s. E. t. valde depressd, albidd, opaciore ; anfractibus iv. et dimidio, quarum tres primi Iceves sunt, suturd haud impressed; striis spiralibus tenuibus, rugulisque incrementi tenuis'simis elegantissime ornatd ; callositate opacd radiatim rugosd circa umbilicum parvum gyrante, juxta labium planatd, pyriformi $ aperturd subovatd, labro tenui, intus suturam vix callosd ; labio tn anfractu penultimo kaud expanso. This extremely elegant and characteristic shell agrees with Vitrinella in the nature of the apex ; but differs in the revolv- ing callus, which is not covered with the spiral striae, but radiately wrinkled ; at the aperture it is suddenly planed off, displaying a pyriform shape. Long. "019, lat. '047 by '037, div. 160. Sab. Mazatlan ; 1 sp. off Spondylus ; L'pool Col. Tablet 1169 contains the specimen. 319. ETHALIA LIRULATA, n. s. E. t. depressd, albd, opacd; anfractibus iv. quarum primi Iteves sunt, suturd haud impressd ; striis spiralibus tenuibus confertissimis ; callositate opacd, circa rimulam umbilicalem gyrante, juxta labium planatd, latd, subtrigond; aperturd ob- ovali; labro tenui, infra suturam minime callosd ; labio inpariete nullo. Known from E. pyricallosa by the compact growth, close striae without transverse wrinkles, and short broad callus 252 MAZATLAN UNIVALVES which covers the umbilicus, leaving only a slight chink. A second sp. agrees in all respects except that the spiral sculp- ture is coarse and somewhat moniliform ; but it is too much weathered to decide on its affinities with confidence. Long. '019, lat. '039 by '034, div. 153. Sab. Mazatlan ; 2 sp. off Chama and Spondylus ; L'pool Col. Tablet 1170 contains the typical specimen. 320. ETHALIA PALLIDULA, n. s. H. t. globosd, solidd, alba ; ad spiram planatd, ad basim pro- ductd ; anfractibus iii., suturd indistinct d, apice planatd ; tot a superficie striis spiralibus subrugulosis impressd ; callositate minima ; umbilico nullo ; aperturd elongatd, ad basim sub- angulatd ; labro acutiore, labio conspicuo. A. little globular shell, produced at the base of the columella, and presenting the general aspect of the young of Lacuna pallidula. It is on the extreme verge of the genus, the com- pact spire preventing the development of the callus. Long. '029, lat. '044 by '035, div. 170. Sab. Mazatlan ; 1 sp. off Spondylus ; L'pool Col. Tablet 1171 contains the specimen. 321. ETHALIA CABIN AT A, n. s. E. t. discoidali, planatd, aurantio-fuscd ; anfractibus iv. et dimidio, quarum iii. primi Iceves, vix amplectentibus, suturd valde impressd ; sub peripheriam acute carinatd ; totd super- ficie rugulis incrementi confertissimis ornatd ; regions umbilicali concavd ; callositate spirali elongatd, angustd, rimam conspicu- am umbilicalem gyrante,juxta labium p arum planatd ; aperturd subquadratd, sinuatd, a carind angulatd ; labio ad parietem nullo ; labro intus suturam parum calloso. This charming little shell has the general aspect of Planorbis carinatus, but with the whirls a very little elevated, and the keel just below the centre. The whirls very slightly embrace, but are cemented by the long, thin callus. Both above and below, it is covered with extremely close, rugulous, radiating striulse. In its mode of growth it affords a transition to Teino- stoma. Long. 013, lat. '038 by '033, div. 175. Sab. Mazatlan ; 2 sp. off Spondylus ; Lpool Col. Tablet 1172 contains the freshest (but smallest) specimen. MAZATLAN UNIVALVES 253 322. ETIIALIA AMPLECTANS, n. s. JE. t. minimd, planald, diaphand, nitidissimd ; anfractibu-s iii, planatis, peritremati rotundato ; callositate haud parvd, umbilicum vix tegente, juxta labium planatd, semilunatd ; labro acuto, supra anfractum penultimum dilatato ; infra sutwam Jiaud impressam callositate, suturamfallacem extus simulante ; aperturd rotundatd. As it is barely possible that this shell may be the young of Teinostoma amplectans, the same specific name has been given. It differs however in the much smaller size of the callosity, which in this shell displays a broad, semi-lunate planation at the columella, which appears characteristic of the species. Long. '016, lat. '04 by '032, div. 180. Hob. Mazatlan ; 4 sp. off Spondylus ; Epool Col. Tablet 1173 contains the freshest specimen. GENTJS TEINOSTOMA, A. Ad. Proc. Zool. Soc. 1853, p. 183. H. $ A. Ad. Gen. vol. i. p,122. Testa spird depressd, politd, anfractibus rapide augentibus ; regione umbilicali callosd ; aperturd productd, elongatd, ab axi remotd ; interstitio calloso ; peritremati axin versus rotundato, ad peripheriam interdum angulato. Shell Eotelloid, with a greatly produced mouth and callus. It resembles Cyclops among the Nassidse, and in the appear- ance of the base reminds the observer of Streptaxis and Anostoma among the Helicidae. Having been described (in English only) from a single species (T. politum, St. Elena, 8 fm. Cuming,) some of the characters before given may here- after prove to be only specific. 323. TEINOSTOMA AMPLECTANS, n. s. T. t. parvd, albd, planatd, Icevi ; peritremati rotundatd ; callositate spirali umbilicum tegente, labium versus subplanatd t fupra parietem intus suturam decurrente ; aperturd rotundatd ; labro supra anfractum penultimum rejlecto ; suturd haud impressd. Although the shells described above as Ethalia may possibly be the young of this species ; yet, as they were all of the sam* June 1856. y 254 MAZATI.AN UNIVALVES size, and there were no intermediate specimens, I have not ven- tured to affiliate them. It differs from T. politum in the absence'of sculpture, (which however would hardly be detected, even under the microscope, without the description,) in the greater reflection of the labrj.m over the spire, and in the very much smaller size. Long. '05, lat. '11 by *07, div. 180. J?a5. Mazatlan ; 1 sp. and fragment off Spondylus ; IS pool Col. Tablet 1174 contains the specimen. 324. TEINOSTOMA SUBSTEIATTTM, n. s. T. t. minima, planatd, opacd, alba, subnitente ; striulis spiralibus prope suturam impressam monstrantibus ; callositate angustissimd, longiore, circa rimam umbilicalem gyrante, prope labium vix planato ; aperturd rotundatd ; labro solido, anfr. penult, baud amplectante. Thig tiny species is known from T. amplectans by the outer lip not being reflected over the spire, which clearly displays the substriated whirls. The callosity is long, but narrow, and scarcely planate at the aperture. A fragment has the suture less impressed. Long. '016, lat. *043 by "032. div. 170. Hob. Mazatlan ; 1 sp. (not quite perfect) and a fragment ; Lpool Col. Tablet 1175 contains the specimen. 325. TBOCHUS , sp. ind. Tablet 1176 contains a fragment of a white shell, tuberculous, with the basal keel smooth j found in additional materials after the genus had been completed. Hob. Mazatlan ; extremely rare, off Spondylus j Lpool Col. Tablet 1177 contains an operculum not affiliated to any known multispiral species. (That of species 291 is however unknown.) It is light horn-coloured, extremely thin, with only about 10 whirls ; margin irregular ; scar lateral, Tablet 1178 contains 2 worn, small, strong, Turbinoid oper- cula, remarkable for the number of whirls, there being at least 10 in a diameter of *046. MAZATLAN UNIVALVES 255 Tablet 1179 contains 2 rubbed opcrcula, which may have been washed up from young Callopoma saxosum. Tablet 1180 contains a shelly operculum (apex broken) which must have had about 10 whirls in a diameter of '45 ; outside nearly smooth, convex ; inside very concave, with the margins of the whirls projecting, and beautifully crenated. Hob. Mazatlan ; from shell washings ; ISpool Col. FAMILY NEBITID.E. GENUS NEBITA, Linn. Odontostoma, Klein, non D'Orb., nee Phil. 4- 326. NEEITA SCABRICOSTA, Lam. An. 5. Vert. vol. viii. p. 608, no. 14. Reel, in Petit Journ. Conch, vol. i. pp. 287, 410, pi. 11, f. 2. C. B. Ad. Pan. Shells, p. 204, no. 304. (Non Deless. in Eec.) =N. [ornata, Sow. Gen.^l. 4, f. 4. Wood, Ind. Test. SuppL pi. 8, f. 4. Eve. Conch. S?/st. pi. 202, f. 4 Phil. AbUld. p. 1, pi. 1, f. 2, 3. Mice, in Zeit.f. Mai. 1850, p. 167, no. 21. Eve. Conch. Ic. pi. 1, f. 3, a, b. + N. Deshayesii, Heel, in Eev. Zool. 1841, p, 184. Eve. Conch. Ic. pi. 2, f. 7, a, b. + N. multijugis, MJce. in Zeit.f. Mai. 1847, p. 179, no. 7, (teste MJce. ipso, loc. cit. 1850,) Eve. Elem. Conch, pi. 16, f.86. = Pila multijugis + P. ornata + P. scabricosta, H. & A. Ad. Gen. i. 379, 380. The N. ornata of Sow. is referred to the N. scabricosta of Lam. on the undoubting authority of Prof. Adams. The original description (from a supposed unique specimen,) might fit many species ; and Desk, (who was debarred by Kien. from inspecting the Lamarckian types, even when editing the An. s. Vert.) does not venture on synonyms. The N. multijugis of Menke, described from adolescent specimens, was abandoned by himself, and yet appears in modern works as distinct. The form N. Deshaysii, (to which most of the Mazatlan specimens belong) is separated in consequence of having more numerous 256 MAZATLAtf UNIVALVES spiral ribs, a taller spire, and a yellow mouth. These charac- ters do not always go together, and are each extremely variable, as are also the rugse on the colmnellar lip, it being difficult to find two specimens exactly alike. The fineness of the ribs sometimes differs in different parts of the same shell. The colour within presents all shades from a brilliant orange to pure white. The sharp labral margin, (crenulated by the ribs,) is either black throughout, or tessellated with light between the ribs. Spire always more or less eroded, even in young speci- mens, which in this collection were extremely rare. These are known from the next species by the non-granular lip (smooth in the youngest specimen,) strong teeth, and raised spire. Costse often scarcely scabrous. Labrum thickly callous within the margin, dentate, with very strong teeth at the extremities. Hugse often continued on the spire, beyond the flattened colu- mella. Operculum (in both the forms IS", ornata and N. Deshayesii) outside finely granular, with an obscure spiral line marking off about a quarter of the shell from the outside, and ending in a deep sinus on the inner margin. Tooth stoutly projecting, curved downwards opposite the not inconspicuous spiral apex. Colour orange brown, A few were found loose, with the spiral line scarcely developed, and of a more ashy colour. As there was no other large species of Nerita among the shells, these are presumed to be of abnormal growth. The following shells, selected from but a small stock, exhibit the principal variations in the wrinkling near the second of the four teeth : to display all the minute differences would have been to retain almost every specimen. The shells are not nearly so large as further down the coast ; the largest measur- ing only long. I'll, lat. 1*18, div. 110 120. Hob. Is. of Timor ; sp. typ. Lam. teste E/ecluz. [?] Real Llejos, Sowerby. Panama ; very common, on rocks, especi- ally in crevices, between high water and three-quarter tide ; young crawling above high water mark on rocks and stones wet with spray ; C. B. Adams S. W. Mexico, P. P. C- Mazatlan ; not common ; L'pool fy Havre Coll. Tablet 1181 contains 4 sp. of different ages: 'the smallest, ' 48 across, displays an orange spire, smooth at the apex, with distant ribs, intercalary ones appearing at the margin. 1182, 1 sp. ribs distant, form ornata. 1183, 1 do., ribs changing, in part very close, form Deshayesii. 1184, 2 sp. displaying col- oured lip; one with a single orange spot, the other richly tinted, inside and out, with spire abnormally elevated. MAZATLAN UNIVALVES 257 Specimens displaying changes of wrinkles. Tablet 1185 con- tains 2 sp. cross-barred, or T-shaped. 1186, 3 sp. curled round, P- or B-shaped. 1187, 2 sp. 7 -shaped. 1188, 2 sp. obscurely F-shaped. 1189, 2 sp. V'^P 6 ^- H90, 1 S P- :--shaped. 1191, 2 sp. wrinkles very slightly developed. Tablet 1192 contains 3 abnormal opercula. Normal ones are seen with the shells. \ 327. NEEITA BEENHABDI, He'd. Petit, Journ. Conch. 1850, vol. i. p. 285. five. Conch. Ic. pi. 12, sp. 57, f. 57, , b. =JSTerita funiculata, Wee. in Zeit.f. Mai. 1850, p. 169, no. 22. (dated "April, 1851.") ? = Nerita, sp. ind. a, C. B. Ad. Pan. Shells, p. 205, no. 309. Theliostyla Bernhardi, If. $ A. Ad. Gen. i. 380. This unpretending, but not inelegant species represents on the Pacific coast the common W. Indian N. tessellata^, from which it differs in the more numerous spiral ribs and columellar granules, and in the irregular style of painting. Shell very variable ; with the spire not a little exserted, or quite flat, the expanded labrum very rarely even projecting beyond. Ribs more or less numerous, generally scabrous, sometimes nearly smooth ; on shells of the same size, they vary from 2 to 5 in the tenth of an inch. Colour black, very irregularly spotted with a variable number of granules, sometimes large, sometimes small : teeth 4, very small and central, sometimes running into lines on the lip, sometimes conspicuous, sometimes nearly obsolete. Operculum ashy, very finely shagreened outside, with a horny layer outside the outer edge, and an inner sinus nearer the middle than in the last species. Tooth scarcely recurved. The largest specimen measures long. '54, lat. '59, div. 120 180. Hab. Peru, Ciiming. Panama ; in extreme profusion, on rocks and stones from half- tide level to the low water mark of neap-tides ; C. B. Adams. S. W. Mexico, P. P. C. Mazatlan ; not uncommon ; ISpool Sf Havre Coll. Tablet 1193 contains 7 sp. various ages. 1194, 7 do. shewing variations in colour. 1195, 6 do. varying in height of spire. 1196, 6 do. young, shewing variations in sculpture. 1197, 6 do. varying in closeness of ribs. 1198, 10 do. shewing changes in the labial teeth and granulations, 1199, 6 separate opercula ; others being in the shells. 268 MAZATLAN UNI VALVES GENUS NEBITINA, Lam. Jtf-eritella, Humph. H. fy A. Ad. Gen. vol i. p. 380. J^ 328. NEEITINA CASSICULUM, Sow. Condi. III. f. 55. TJies. Conch, p. 521, no. 47, pi. 115, , 194 Mke. in Zeit.f. Mai. 1850, p. 116, no. 19. If. & A. Ad. Gen. i. 382. Comp. N. faba, Sow. Thes. Condi, p. 530, no. 78, pi. 115, f. 219 221. Conch. IU. f. 10. ( = Clithon f. H. & A. Ad. Gen. I 385.) Comp. Neritina California, Eve. Conch. Ic. pi. 4 sp. 20, f. 20, a, b. (Gulf of California, Mus. Cuining.) Although picked specimens may be found so far distinct from JNT. picta that Messrs. Adams have placed them in differ- ent subgenera, individuals may be found in, each species so nearly alike that it is not impossible that they may ultimately prove to be identical* They display exactly the same varieties of form, although they are much more constant in colour. The differences observed are as follows. This species is larger ; mouth white and stained with orange ; inner lip rather flat- tened; teeth smaller and more irregular, more resembling those of JN". virginea ; opereulurn longer, with broader dark border, richer orange colour within, and medial line scarcely marked. If N. faba does not differ more than is stated in Sow.'s description, it may prove identical. He characterizes it as resembling JS". picta, but having "the spire rather more hidden, and the columella neither swelled [? swollen] no* of a chesnut colour." It belongs however to another genus, teste H. 6f ^L. Aa Whether these and connected species in the Pacific oe realiy distinct from JS". virginea with its many-named varieties from the Atlantic, it must be for those to judge who have examined large series from different localities. The form exists in the B. M. from China, Philippine Is., and Port Essing- ton. It is found on the coasts of Spain and reaches Dalmatia. A regularly formed sp. measures long. *68, lat. '83, div. 120. A flattened '57, '72, 145. An elevated '73, *77, 90. * As such I have freely distributed specimens. It is not unlikely that Prof. Adams regarded them as the same, "liie specimens which Lieut. Green col- lected aro of extraordinary size." Pan. Shells, p. 207. MAZATLAN UNIVALVES 259 Hob. (Unknown, Sow.) Mazatlan, Menke. Mazatlan ; com- mon, generally coated with black accretion, similar to that adhering to Strigilla carnaria, Terebra albocincta, Area tuberculosa, &c. ; L'pool Col. Tablet 1200 contains 2 sp. apex sunken. 1201, 5 sp. last whirl swollen, apex appearing. 1202, 5 do. last whirl less swollen. 1203, 5 sp. normal form. 1204, 6 sp. apex more raised. 1205, sp. still more. 1206, 3 do. extremely raised, mouth very slanting. 1207, 5 sp. violet tinge. 1208, 5 separate opercula ; others being in their shells. ^ 329. NERITINA PICTA, Sow. Proc. ZpoL Soc. 1832, p. 201. Desk, in Lam. An. s. Vert. vol. viii. p. 588, no. 40. Sow. Conch. III. no. 35, pi. 86, f. 1 : Thes. Conch, p. 530, pi, 116, f. 267-9. Mke. in Zeit. f. Mai. 1850, p. 167, no. 30. C. B. Ad. Pan. Shells, p. 206, no. 307. Rve. Condi. Ic. pi. 23, sp. 101, f. 101, a, b. Yitta picta, -BT. Sf A. Ad. Gen. i. 383. Comp. N. Guayaquilensis, D'Orb. Sow. 'Thes. Qonch. p. 520, no. 44, pi. 114, f. IW.Rve. Conch. Ic. pi. 23, sp. 104, f. 103 b. (nona.) Comp. N. Fontaineana, B. M. Cat. D'Orb. Moll. p. 34, no. 305. (Rio de Guayaquil.) The variations in this species are extraordinary. Not only does it present the changes of colouring recorded below, but the form is very inconstant. Sometimes it is nearly globular, with the spire not exserted and flattened ; sometimes it is much produced. Sometimes the mouth is nearly straight with regard to the axis ; sometimes very slanting. Sometimes the outer lip is regular, sometimes anteriorly lengthened. The brown spot which is supposed to be characteristic of the species varies in intensity, and is scarcely seen in very young shells. It is not uncommon to find specimens whose apex betokens a different painting from that afterwards adopted ; and to find shells whose back affords one pattern and the front another. The denticulatioa also of the inner lip varies in intensity and arrangement ; so that it is difficult to assign any character, by which the whole species may be included and at the same time separated from its neighbours. The operculum is grey outside with an exterior horny layer, and a ridge near the straight 260 MAZATLA.N UNIVALVES edge : within it is yellowish, green, with two orange projecting teeth, one conical at the nucleus, the other spiral; with a slightly raised central spiral line. The measurements vary as in the last species ; or*? of ordinary growth measures long. '5, lat. '63, div. 130. Sab. Panama ; on a mud bank partially overflowed with fresh water ; Cuming. Do. ; on sticks and stones, in a grove of trees, a little above half tide level ; also in dirty places on rocks at or a little below half tide level ; strictly marine ; C. B, Adams. San Miguel ; of extraordinary size ; Lieut. Green. JMazatlan, Menke. California [PTJpper] Lady Doug- lass, B. M. "Australia ; given by Metcalf, Esq."* B. M. Mazatlan ; abundant, sometimes pierced by Grastero- pods ; L'pool fy Savre Coll. Ordinary network pattern ; lilac tinge. Tablet 1209 contains 12 specimens very close pattern. 1210, 7 do. close. 1211, 7 do. open. 1212, 5 do. very open. Obscurely trifasciate. 1213, 12 do. very close. 1214, 12 do. close. 1215, 8 do. onen. 1216, 6 do. very open. 1217, 6 do. colour changing. Grey tinge. 1218, 3 do. extremely light. 1219, 6 do. with rows of dots. 1220 r 5 do. greenish. 1221, 5 do. spotted suture. 1222, 7 do. darker. 1223, 3 do. close pattern. 1224, 5 do. obscurely tri- fasciate. Very dark colour. 1225, 4 sp. grey tinge, very close markings. 1226, 4 do. close. 1227, 4 do. brown tinge. 1228, 4 do. purple tinge. 1229, 7 do. nearly black. 1230, 4 do. obscurely trifasciate. Striped and zigzag pattern. Tablet 1231 contains 8 sp. inter- mediate. Grey and olive green tinge. 1232, 6 do. light. 1233, 9 do. with black sutural spots. 1234, 4 do. grey. 1235, 9 do, olive appearing. 1236, 5 do. dark striped. 1237, 7 do. light olive, fine streaks. 1238, 7 do. broader streaks. 1239, 5 do. dark olive, close streaks. 124D, 5 do. more distant streaks. 1241, 3 do. mottled. 1242, 5 do. grey appearing. 1243, 4 do. very close pattern. 1244, 4 do. less close. 1245, 5 do. yellow appearing. Lilac tinge. 1246, 5 do. dark. 1247, 5 do. light. 1248, 7 do. vellow appearing. Yelloio and greenish tinge. 1249, 6 do. very light. 1250, 7 do. light 1251, 6 do. darker. 1252, 5 do. long stripes. 1253, 2 do. broader. 1254, 7 do. large * Several Mazatlan shells (known by their habit as well as by their species) occuring in the B. M. with the above inscription, it is probable that they were procured from the Ha\re Col. which was sold piecemeal at the London auctions, without any assigned habitat ; and that Mr. Metcalf erroneously supposed them to have come from Australia. MAZATLAN TJN1TALTES 261 sntural yellow patches. 1255, 7 do. greener. 1256, 7 do. dark- er. 1257, 2 do. intermediate. 1258, 5 do. close grained. 1259, 4 do. striped. 1260, 7 do. obscurely trifasciate. 1261, 4 do. dark close pattern, fine lines. 1262, 5 do. coarser lines. 1263, 7 do. mottled pattern. 1264, 5 do. obscurely trifasciate. Olive green tinge. 1265, 5 do. very light. 1266, 7 do. rather darker. 1267, 7 do. greyish tinge. 1268, 5 do. darker. 1269, 7 do. very dark. 1270, 5 do. closer markings.^ 1271, 8 do. obscurely trifasciate. Banded variety. Grey tinge. 1272, 7 sp. close pattern. 1273, 4 do. speckled. 1274, 6 do. band more developed. 1275, 4 do. band coloured. Lilac tinge. 1276, 9 do. close pattern. 1277, 7 do. greenish band. 1278, 7 do. variable markings. 1279, 5 do. open pattern. 1280, 9 do. band margin with broad spots. 1281, 10 do. narrow spots. 1282, 8 do. with white lines. 1283, 4 do. without white. Greenish tinge. 1284, 4 do. light, streaked. 1285, 5 do. spotted. 1286, 4 do. large spots. 1287, 3 do. broken markings. 1288, 5 do. large zigzag pat- tern. 1289, 4 do. band spotted. Dark volour. 1290, 8 do. with yellow flames. 1291, 4 do. fine markings. 1292, 7 do. broken pattern. 1293, 5 do. very close grains. 1294, 7 do. very dark. With black sutural land. Spotted. 1295, 3 sp. very light. 1296, 5 do. lilac, open pattern. 1297, 5 do. grey. 1298, 4 do. close pattern. 1299, 5 do. dark lilac. 1300, 4 do. dark grey. 1301, 4 do. very dark. Striped. 1302, 4 do. very light. 1303, 9 do. olive green. 1304, 8 do. grey. 1305, 4 do. dark. Banded. 1306, 5 do. lilac tinge, speckled. 1307, 6 do. grey. 1308, 4 do. striped. 1309, 3 do. lilac and green. Tablet 1310, contains 11 sp. shewing variations in form. 1311, 18 sp. shewing variations in the mouth. In all, 607 specimens, between every two of which there is an appreciable difference. The above enumeration gives but a faint idea of the variations, fully to display which every specimen must have been retained, and to describe which' would have filled a volume. Tablet 1312 contains 30 separate opercula ; others are seeu in situ. 262 MAZATLAN UNIVALVES OEDEE PECTESTIBEANCHIATA. SUBOEDEB EOSTEIFEEA. FAMILY YAOTCOEIDJE. GENUS VANICOEO, Quo?/ $ Gaim. Vanikoro, Quoy fy G-aim., Voy. a prima manu ; (postea Sigaretus seu VelutinaJ Gray, Proc. Zool. Soe. 1847, p. 156, no. 256. H. $ A. Ad. Gen. vol. i. p. 374. Narica, Red. in Sagr. Cub. Moll. 1836, teste Phil. JIandb. Conck. p. 184. "M. Eecl. lias the intention to form a genus," D'Orb. Cuba, vol. ii. p. 39 : genus constituted, 1844: teste Gray. Merria, Gray, Zool. Seech. Voy. 1839, p. 137, (anim. descr.) Leucotis, Swains. 1840, Treatise, p. 346. ^ 330. VANICOEO CBYPTOPHILA, n. s. V. t. parvd, Sigaretoided, tenui, albidd ; nucleo awfr. iii. quorum primus planatus, alteri subturriti, tenuissiine striati, decliviter sito ; anfr.normalibus ii. rapide augentibus,subplana- iis, irregularity striulis spiralibus creberrimis et striis incre- menti, interdum his, interdwn illis superantilus, tenuissime cancellatis ; apertura valde expansa, vix peripkeriam penul- timam attingente ; labro elongato, labio recto ; umbilico maxima ; peripherid angustiore. This little creature resembles the Calyptrseidge in its seden- tary habits, frequenting the burrows of worms, &c. in Spondylus and Chama valves, where its flattened form and advanced lip (in this respect resembling Trochita) allow it to live in a very- narrow space. Many specimens were ( found in situ, but there was no trace of operculum. A minute shell of one whirl (found inside the mouth of another,) is perfectly formed, like a tumid Planorbis. Another, which was adhering over tke umbilicus of an adult, is just preparing to commence the normal portion, and is shaped like a Bithinia. It then lays its spire sideways, but not always at the same angle, and begins a flattened Sigaretoid growth. The sculpture is extremely variable, sometimes nearly evanescent. Most of. the 85 specimens found were very small; the nuclear shell measures *02 by '016; a remarkably large specimen measures long. '15, lat. '17 by 15. MAZATLAN UNIVALVES 263 Hob. Mazatlan ; rare, in worm-eaten passages and burrows of Spondylus and Chama ; L'pool Col. Tablet 1313 contains the fry inside an adnlt, the nuclear shell, and 2 sp. in the first stage of normal growth. 1314, a series of 8 sp. of different ages and patterns. One has its mouth filled with most beautiful spiculse of sponge. 1315, a sp. in situ in a fragment of Spondylus. FAMILY The genera of this family, united by Lesson, Broderip and Deshayes, though very different when adult in their principal forms, are so closely related when young that if the fry be examined when just emerging from the spiral nucleus it would be difficult to say into which genus each shell would develop. The ordinary young state of Crucibulum has only half a cup, each side being laterally adherent, resembling on tne one hand the sunken Crepidulse, as C. adunca, on the other, (supposing the half-cup to grow forward separate) Calyptrsea proper, (C. equestris, &c.) The amount of lateral adherence, the absence of which forms the subgenus Calyptrsea a of JJrod., (C. rudis, Brod. = umbrella, Desk.) varies in specimens of the same species. The internal lamina, more or less spread out or lobed in species of Crepidula, with the margins? doubled together forming a cup in Crucibulum, is in Galerus very slightly turned over and flattened, these characters varying in the species. Trochita is simply an extreme of Galerus on the one hand, or of the spiral Crepidulse on the other. For par- ticulars of the generic synomyms, v. Grays Synopsis in Proc. Zool. Soc. 1847, p. 157 ; H. # A. Ad. Gen. vol. i. p. 363 ; Phil. j&andb. ConcJi. p. 186. For particulars of species, v. Brod. in Proc. Zool. Soc. 1834, p. 35 ; id. Trans. Zool. Soc. ; Desk, in Lam. An. s. Vert. vol. vii. p. 619 ; C. B. Ad. Pan. Shells, p. 219 ; B. M. Cat. D'Orl. Moll. p. 47. Menke's species, given in Zeit. f. Mai. 18461851, are not described with sufficient accuracy to allow gf certain allocation. They seem often named from worn and young specimens, and would probably have received great revision, had the author examined a la^ge series of specimens like the present. As he is describing Mazatlan and not New Zealand shells (as his names would sometimes imply), his species are here allotted acording to the preponderance of characters. The following genera are 264 MAZATLAtt UNIVALVES adopted from their great convenience. Of Calyptraea proper, which is the best marked in its characters and is well repre- sented both in individuals and species in the Caribbean and equatorial West American Seas, only a single individual was found in the entire Mazatlan collection. None of the species were found with a solid shelly attachment, though a thin deposit may sometimes perhaps be traced. In general a cavity is excavated on the backs of other sheDs. FAMILY GENUS TEOCHITA, Schum. Schum. Ess. no. 11, 1815. Gray, Proc. Zool Soc. 1847, p. 158, no. 272. Phil. Eandb. Conch, p. 187. JZ". fy A. Ad. Gen. i. 367. Trochus, pars, Lam. Calyptrsea, pars, Desk. Sigapatella, Lest* 1829, Voy. Coq Trochatella, Less. 1830, (teste Gray.) In- fundibulum, D'Orb. 1846, non Montf. This genus forms an exact transition in the shell from the spiral Crepidulse to the Phoridse, the animal of; which is widely different. It is in fact a Crepidula, with the anterior part shortened, while the posterior is lengthened. Several species might be ranked with either genus. It is represented in the Mazatlan collection by a single specimen. 331. TEOCHITA VENTEICOSA, n. s. T. t. ventricosd, subdepressd, irregulari ; albidd, castanco tmbutd ; anfractibus iii. [? aut pluribus} ventricosis, maxim* prope suturam ad any. 90 depressam ; superficie irregulariter noduloso-rugosa, rugis subobsolelis, diagonalibus, nodulis hue et illuc prope suturam extantibus ; totd pagind creberrime et minutissime corrugatd; epidermide lamellosa, cornea, maxime prope marginem, indutd ; cavitate concavo ; lamina albd, tineas incrementi haud monstranti> labioparum reflexo^umbiliconullo; mar gine forma sedis convenicnte. Conrp. Trochita radians, (Desk, teste H. SfA.Ad. Gen. i. 367,) DJcr. Ind. Moll. Guin. p. 36, no. 97: = Trochus r. Lam. An. s. Vert. (ed. I,) vol. vii. p. 11, no. 5 : Sckub. fy Wagn. Chemn. Suppl. pi. 229, f. 4063 : = Calyptrsea r. Lam. ed. Desk. vol. vii. p. 626, no. 8 : =Infundibulum r. Zool. Beech. Voy. p. 148, pL 39, f. 10, 11 : =PateUa trochiformis, Chemn. MAZATLAN UNIVALVES 265 vol. x. pi. 168, f. 16267 iDilliv. Eec. Shells, p. 1018, no. 6: =Calyptrsea (Trochatella) t. B. M. Cat. D'Orb. Moll. p. 48, no 411 : + Patella trochoides, Dillw. loc. cit. no. 7: + Calyptraea Araucana, Less, (teste D'Orb. Cat.) PJun. = Calyptrea dilatata, Sow. Gen. f. 9, (non Crepidula d., f. 5.) Calyptrsea radians, (max,) Vol. Voy. Ven. pi. 14, f. 3 5 pi. 15, f. 4. Of this beautiful species, besides the specimen here des- cribed, I have seen only one other, in the collection of T. Nuttall, Esq., from an unknown locality. It differs from the S. American T. radians, (also quoted from Benguela and St. Vincent, Guinea, on the authority of Dr. Tarns ; and of which, a remarkably conical variety is figured in Beechey's Voyage ;) and also from the Gulf species, T. spirata, in the great con- vexity of the whirls, which are so produced at the shoulder that the sides of the suture form nearly a right angle. It ap- proaches most nearly to a fossil species from Dax, which however has the base still more concave. The Infundibulum Californicum, H. Ad., (Proc. Zool. Soc. 1851, p. 153,) which from its name might be supposed to have some connection, is a species of Poly donta, (Trochinse.) Diam. '74, alt. '64, (eujus anf. ult. '48,) div. 110. Hob. Mazatlan ; one fresh sp. ; IS pool Col. Tablet 1316 contains the specimen. GENUS GALEBUS, Gray. Galerus, Humph. 1797: Gray, Proc. Zool. Soc. 1847, p. 157, no. 269 :Phil. Handb. Conch, p. 187 : H. fy A. Ad. Gen. vol. i. p. 367. Trochita (pars,) Schum. 1817. Calyptrsea (pars,) Lam. 1822. Siphopatella (pars,) Brod. 1834. Infundibulum, pars, J. Sow. TrochateUa, pars, D'Orb. Mitrula, Gray, 1821. Trochilea, Swains. 1837. This genus is intermediate between Crepidula or Crucibulum, and Trochita. The shell is conical, slightly spiral, with a rapidly ascending spiral lamina, doubled in upon itself. Unfor- tunately, no very young shells were found of this section. The plane of the vertex is parallel to the base in all observed species. | 332. GALEEUS CONIGUS, Brod. Calyptraea (Siphopatella) conica, Brod. Proc. Zool. Soc. 1834, 'p. 38: Trans. Zool. Sac. voL i. p. 202, .pi, 27, f. 7.MML July 1856. * 266 MAZATLAN UNIVALVES Si/n. Noo. Test. Viv. p. 147. (Calyptrsea c.) Lam,. An. s. Vert. vol. vii. p. 630, no. 17. C. B. Ad. Pan. Shells, p. 220, no. 333. (C. Trochatella c.) Wee. Zeit. f. Mai. 1851, p. 36, no. 126. (Galerus c.) H. $ A. Ad. Gen. i. 368. The nuclear vertex in this species is generally eroded ; but, when perfect, resembles that of G-. Sinensis, about "02 across, not prominent, with the outer whirl enveloping the rest, apex not visible. The colour is of a beautiful pinkish brown, lustrous, uniform over the shell, and variously stained or spot- ted. The lamina makes a rapid ascent to the margin, is much flattened, with the inner edge elegantly rounded, recurved over from 3-4ths to 4-5ths of its breadth, and a third part of its length. The recurved part is open, but not swollen within. Long. 1'27, lot. 1*17, alt. '66. Hal). Xipixapi and Salango, attached to shells in deep water, Cuming. Panama, very rare, C. B. Adams. S. W. Mexico, P. P. C. Mazatlan ; extremely rare ; L'pool Col. Tablet 1317 contains 4 sp. of which the youngest is '08 across, and the next is coloured as in C. lichen, Brod. f- 333. GALERUS MAMILLAEIS, Brod. Calyptrsea (Siphopatella) mamillaris, Proc. Zool. Soc. 1834, p. 38 -Trans. Zool. Soc. vol. i. p. 201, pi. 28, f. 5. (Calyp- trrca m.) Lam. An. s. Vert. vol. vii. p. 631, no. 18. (Galems m.) H. $ A. Ad. Gen. i. 368. (Non C, Trochatella m. B. If. Cat. V Orb. Moll. p. 48, no. 412.) + Calyptrsea regularis, C. B. Ad. Pan. Shells, p. 224, no. 340 : id. p. 320. (Galerus r.) H. fy A. Ad. Gen, i. 368. = Calyptrsea (Trochatella) Lamarcldi, Mke. Zeit'. f. Hal. 1847, p. 188, no. 37: id. 1851, p. 36, no. 125. (JSTon Desk. Lam. An. s. Vert., vol. vii. p. 627. no. 9.) ? + Calyptrsea (Siphopatella) Lichen, Brod. Proc. Zool. Soc. 1834, p. 37 -Trans. Zool. Soc. vol. i. p. 201, pi. 28, f. 4. (Calyptrsea 1.) Lam. An. s. Vert. vol. vii. p* 630, no. 16. (Galerus 1.) H. ^A.Ad.i. 368.-(Teste B. M. Cat. D'Orb. Moll. p. 48, no. 412, = "lorica" err. typ.) The specimens of G. mamillaris in the Cumingian collection vary greatly in colour and sculpture. . Some of these, as well as G. lichen, closely resemble the young of G. co*nica. A microscopic examination of the nuclear vertices would prp- bably decide the question. The vertex of G. mamillaris is MAZATLAN UNIVALVES 267 about '02 across, generally rather separated from the shell, and of an elegant discoidal shape like Planorbis, displaying the whirls and the sunken apex. The whirls increase rapidly and regularly, sometimes developing concentric wrinkles (as in Crep. nivea,) just beyond the nuclear portion. The internal lamina makes a more complete revolution than in G. conica ; the central margin is more produced, and the reflection is only over half the breadth. The Mazatlan shells differ from G. Sinensis and its W. Indian congener, in the reflection of the lip, which is nowhere closed, in the character of the nucleus, and in the non-spinous surface.* The colour is often of a rich brown within and near the vertex ; otherwise of a dingy white. Epidermis very thin. The cone is more or less depressed. The form Gr. lichen is probably only a flattened variety of this species ; but may be distinct. The C. mamillaris of D'Orb. is the C. unguis of Brod. and appears a distinct species, of which the C. sordida of Brod. is probably a variety : the lamina being so much reflexed as to pass into Crucibulum, the young of which however it does not at all resemble. The ordinary size of G. mamillaris is as in Gr. Sinensis ; an extraordinarily large one measures long. 1*26, lat. 1'23, alt. '56. Hob. Isl. Muerte ; on dead shells, sandy mud, 11 fm. ; Cum- ing. (Gr. lichen.) Idem, Cuming. (Gr. regularis) Panama ; extremely rare; C. B. Adams. Acapulco, Col. Jeivett. Sta. Barbara, Col. Jewett. Mazatlan ; not uncommon, ad- hering to shells, and to each other ; Lpool Col. Payta to Guayaquil, IfOrbigny. Tablet 1318 contains 6 pale specimens. 1319, 6 do. dark colour, (one in situ.) 1320, the largest specimen. GENUS CKEPIDTJLA, Lam. Crepidula, Lam. 1799. Phil. Handb. Conch, p. 188. Sandalium, ScJium. 1817. Crypta (Humph. 1797) Gray, 1847 : H. <$f A. Ad. Gen, vol. i. p. 368. The species of this genus run into each other in the most marvelous manner. The characters even of the young shell * The W. Indian analogue of this species is Calyptrsea laevigata, Lam. : T. Deless. Rec. Coq. Lam. pi. 25, f. 3 a, b, c. The C. extinctorium, Lam. (quoted by Sow. for a totally different shell) appears from the same work, loc. cit. f. 2, a, 5, c. to be a somewhat similar, blackish Galerus, in which however the outside and the inside representations of the spiral element do not agree. 268 MAZATLAN UNIVALVES are often by no means constant. It has been the object, in the following selection from the multitudes of individuals in the Mazatlan collection, to illustrate the variations of which each species is susceptible.* 334. CEEPIDULA ACULEATA, Gmel. PateUa aculeata, Gmel. p. 3693. Dillw. Descr. Cat. p. 1020, no. 11. Patella fornicata aculeata, Chemn. Conch. Cab. vol. x., p. 334, pi. 168, f. 1624-5. Patella fornicata, var. Sclireib. Conch, vol. i. p. 338. La Retorte epineuse, Favanne, vol. i. p. 564, pi. 4, f. F. 2. Crepidula aculeata, Lam. An. s. Vert. vol. vii. p. 642, no. 3. Desh. Fnc. Meth. Vers, vol. ii. p. 27, no. 11. Sow. Gen. f. ^B. M. Cat. Cuba Moll. p. 33, no. 395. .S. M. Cat. D'Orb. Moll. p. 48, no. 415. WBrod. in Proc. Zool. Soc. 1834, p. 39 Gould, ms. Cat. Cal. Shells Dkr. Ind. Moll. Guin. no. 94. Krauss Sudafr. Moll. p. 69, no. 4. Crepipatelia aculeata, H. $ A. Ad. Gen. i. 369. + Crepidula Capensis, B.M.\ (?=Quoy fy Gaim. Voy. Astr. vol. iii. p. 424, pi. 72, f. 13, 14 ; Lam. An. s. Vert. vol. vii. p. 645, no. 9 -.Krauss, Sudafr. Moll. p. 68, no. 1.) + Calyptrsea (Crepipatelia) echinus, Brod. in Proc. Zool. Soc. 1834 p. 39 Trans. Zool Soc. vol. i. p. 203, pi. 27, f. I Mull. Syn. Nov. Test. Viv. p. 148. H. $ A. Ad. Gen. i. p. 369. (Crepidula e.) Lam. An. s. Vert. vol. vii. p. 650, no. 23. C. B. Ad. Pan. Shells, p. 226, no. 344. + Calyptraea (Crepipatelia) hystrix, Brod. Proc. Zool. Soc. 1834, p. 39 -.Trans. Zool. Soc. vol. i. p. 203, pi. 29, f. 2. H. fy A. Ad. Gen. i. p. 369. (Crepidula h.) Lam. An. s. Vert. vol. vii. p. 650, no. 22. + Crepidula cosi^ta, Mke. in Zeit.f. Mal.l84!7, p. 183, no. 32 : (non Sow. nee Quoy, nee Desh. in Lam. An. s. Vert. vol. vii. p. 644, no. 7.) Id. 1851, p. 35, no. 122. + Crepidula Californica, Nuit. ms. in Warrington Mus. * I have been compelled to unite several species usually regarded as very dis- tinct. On shewing a series to an author deservedly distinguished, proving that four species were identical which he had grouped under two subgenera, he com- plained that I had kept all the puzzling shells ! It is easy, as one naturalist is recorded to have done, to smash all specimens not according with our classifica- tion; or as another, to pick out all the leading forms and describe them as distinct species, genera, or even orders, disregarding the intermediate ones which would have proved them identical ; but the interests of science are not served by either one course or the other. Our object must ever be, not to make Nature aweak our language, but to find out what is the language of Nature. MAZATLAN UNIVALVES 209 My attempts to find specific differences between the Atlantic and Pacific shells have entirely failed. The former are generally of a more reddish, the latter of a browner cast ; but those from Chili belong to the Atlantic type ; while those from Honduras go through the same changes as the Mazatlan shells. The Patagonian shells may belong to either type. The C. echinus of Brod. represents the form in which all the ribs are equal and very spiny ; the C. hystrix that in which a few are developed, with large spines, at the expense of the rest. The two forms run into one another, and into the common form almost imperceptibly. In first describing them, Brod. candidly states that he would not be positive that they are not all varie- ties of C. aculeata. There is a distinct variety which bears the same relation to the typical form that C. squama does to C. nivea. It is flat, very regular, without spines, but covered with extremely crowded imbricated scales. The Californian variety is the most aberrant, being small, nearly round, and never spiny. It might pass for a distinct species, were it not that a few of Mr. Nuttall's specimens exactly belong to the Mazatlan type, while some few of the degenerated Mazatlan specimens are closely allied to those from Monterey. The young shells which Menke obtained from coral on Spondylus, Chama, and Murex nigritus, and affiliated to the New Zealand form, (so well marked that it received the same name from three distinct sources), appears from the diagnosis to belong to this species. C. aculeata belongs to the group of regularly spiral Cre- pidulae. It begins life as a smooth, glossy, light horn-coloured, Yelutina-shaped shell, with rapidly increasing whirls, and a sunken apex. This is much larger than the nuclear part of C. nivea, though the adult shell is much smaller ; being about '025 across when it begins its second stage. C. nivea begins with concentric ridges and goes on smooth, rapidly increasing, but in a regular curve. C. aculeata makes a sudden expansion when forming its deck, and then develops ridges as in the form C. Lessonii. These soon become more or less undulated, and then assume the state of vaulted spines, differing incize and arrangement, and in the period at which they commence. At the same time various rays or spots of chesnut colour appear. Within, the growth of this species offers a well marked contrast to that of C. nivea and its congeners. Instead of forming a basal columella lip and then throwing up a deck at a considerable angle, this shell makes the columella lip the 270 MAZATlltf UNIVALVES commencement .of its deck, which it continues from it in a regular curve. The marginal lip also is very short, not cover- ing the spire as in C. nivea, &c., but leaving it for a long time very conspicuous. The shell in its early decked stage has much the appearance of a INeritina. The deck however is extremely thin, always displaying striae of growth. It soon develops a central sinus, leaving the margin arcuated, not angulated. From this regular spiral growth, the transition is easy, through other species, to the form Trochita. The adult shell has normally a deck margin of the form rx^Avn, one side of the "brace being longer than the other. The point develops a spiral line to the apex. Sometimes however this point is rounded ; each sinus and lobe may be developed at the expense of the rest ; and in one specimen, the outer lobe being pointed while the middle point is rounded, the margin assumes the form of an irregular inverted brace ^^y^J. The ordinary colour is a yellowish white variously striped, spotted or mottled with lustrous chesnut or dark brown. Barely the whole shell is dark brown, most rarely pure white. The red tints observ- able in the Chili and Atlantic specimens have not been found in the Gulf district : they are not mentioned however in Dillwyn's description, and "perhaps are duo to the fading of the brown, most of the W. Indian specimens in collections being dead. Those brought by Mr. D. Dyson from Honduras are coloured like the Mazatlan specimens. The external markings, on which Brod.'s species are founded, are extremely variable. Well developed specimens of hystrix and echinus are rare ; but intermediate forms between these and the common state with irregular crowded small vaulted spines, are abundant. The W. Indian specimens moreover go through the same changes of sculpture. The delicately grown shells, which are flatter and broader in proportion, are rough to the touch, but the spines are scarcely discernible without a glass. On coarse- ly grown shells, they are often not developed over part of the surface. The amount of spiral involution varies considerably in different specimens. (Comp. C. Calyptrseiforrnis, Desk, in Lam. An. s. Vert. vol. vii. p. 647, no. 15.)* The smallest specimen is '03 in length. The largest sp. measures long. 1'73, lat. 1*06, alt. '41. A convex sp. ,, 1'12, "87, '46. Aflatsp. I'l, 1', '26. An elongated sp. '8, '41, '19. A convolute sp., apex to front '68, to back '33. A straight sp. '92, '18. MAZATLAN UNIVALVES 271 A long decked sp., margin to front *36, to lack '47. A short do. '48, "3. Hab.(C. aculeata) W. Indies, passim, auct. Cuba, Sagra. Honduras, Dyson. Brazils : Patagonia ; D' Orbigny. Ben- guela ; 1 sp. in excellent preservation ; Tarns. Table Bay, Krauss. Cape Natal, Mus. Cuming. Isle of France, Fav- anne. Kurachee, Mouth of the Indus, Mus. Cuming. Port Jackson, Rev. It. L. King. New Zealand, Rev. It. Taylor. Sydney and Swan Eiver, Mus. Cuming. (Dark var.) Japan, Mus. Cuming. (Light var.) Chili, Capt. Ld. Byron. (C. echinus, &c ? ) Lobos Is. Peru, Cuming. Panama; under stones at low water, rare ; C. B. Adams. (C. Calif ornica) Monterey, common, Nuttall. Mazatlan ; common, on shells &c. ; young shells abundant on Chamse and Spondyli ; L'pool Col. Tablet 1321 contains 10 sp. extremely young. 1322, 7 do. a stage older, with a fragment to shew the inner surface of the deck. 1323, a young deformed shell, nearly smooth, probably belonging to this species. Specimens illustrating form and sculpture. Tablet 1324 con- tains 8 sp. (var. hystrix) of different ages. 1325, 13 sp. do. (var. echinus.) 1326, 8 sp. do. finely aculeate, arched. 1327, 10 sp. do. flat, (one of the young in situ on an adult.) 1328, 8 sp. do. spiny processes 'imperfectly developed. 1329, 4 sp. do. (var. Calif ornica.) 1330, a series of 12 sp. shewing gradations between the above forms. 1331, 7 sp. shewing gradations from flat to arched. 1332, 6 sp. shewing gradations in amount of spiral involution. 1333, 5 sp. shewing gradations in size of deck. 1334, 6 sp. shewing gradations in prominence or sinking of deck. Specimens skewing shape of deck. Tablet 1335 contains 3 sp. center pointed, sides much swollen. 1336, 4 do. sides swollen. 1337, 3 do. sides slightly swollen. 1338, 3 do. center rounded. 1339, 1 do. point turned outwards .1340, 4 do. form approaching C. nivea. 1341, 3 do. deck partially opaque. Specimens displaying changes of colour. Tablet 1342 contains 2 sp. (hystrix and echinus) pure white. 1343, 10 sp. variously shading into brown. 1344, 11 sp. , do. dark lustrous brown. 1345, 12 sp. tortoiseshell, variously mottled. 1346, 5 do. whiter tint. 1347, 6 do. more or less tinged with green. Distorted specimens. Tablet 1348 contains 7 sp. of irregular shape. 1349, 7 sp. diseased by worms. 1350, 3 sp. with addi- tional margin. 1351, 4 sp. passing towards C. nivea. 1352, 3 sp. passing towards C. onyx. 272 HAZATLAN UNIVALVES 335. CBEPIDULA DILATATA, Lam. An. s. Vert. vol. vii. p. 644, no. 5. Deles. Rec. Coq. Lam. pi. 25, f. 4>, a, b, c.Sozv. Gen. f. 5,jun.B. M. Cat. DOrb. Moll. p. 49, no. 418. Var. Brod. Proc. Zool. Soc. 1834, p. 38 -.Trans. Zool. Soc. vol. 1. p. 203, no. 21, pi. 28, f. 11- (Crepipatella d.) H. fy A, Ad. Gen. i. 369. 4- Crepidula depressa, Desk. Enc. Meth. Yers, vol ii. p. 26, no. 5. (Pteste Desk.) + Crepidula Peruviana, Lam. An. s. Vert. vol. vii. p. 49, no. 6. Deles. Rec. Coq. Lam. pi. 25, f. 5, a, b, c.DJcr. Ind. Moll. Gum. p. 35, no. 95.- (Crypta P.) S. fy A. Ad. Gen. i. 369. + Crepidula patula, Desk. Enc. Meth. Yers, vol. ii. p. 27, no. 9. Lam. An. s. Vert. vol. vii. p. 646, no. 13. (Crypta p.) H. '# A. Ad. Gen. i. 369. = Crepidula Adolphei, Less. Voy. Coq. Zool. vol. ii. pi. 15, f. 2, 2A. anim. revers. (CrepipateUa A.) JI. & A. Ad. Gen. i. 369. + Crepidula Nautiloides, Less, (teste If Orb. Cat.) + Calyptrsea (Crepipatella) strigata, Brod. Proc. Zool. Soc. 1834, p. 39 -.Trans. Zool. Soc. vol. i. p. 203, pi. 28, f. 12. Zool. Beech. Voy. p. 148, pi. 39, f. 13. (Crepidula s.) Lam. An. s. Vert. vol. vii. p. 651, no. 24. Crepipatella s.) H. fy A. Ad. Gen. i. 369. (teste DOrb. Cat. : P? teste Brod. ipse.) ?? + Calyptrsea (Crepipatella) pallida, Brod. Proc. Zool. Soc. 1834, p. 39 -.Trans. Zool. Soc. vol. i. p. 204, pi. 29, f. 3. (Crepidula p.) Lam. An, s. Vert. vol. vii. p. 650, no. 21. CrepipateUa p. H. $ A. Ad. Gen. i. 269. (teste DOrb. Cat.) + Crepidula areuata, DOrb. [quasi BrodJ] B. M. Cat. Moll. p. 49, no. 420. (teste Gray.) ? + Calyptrsea (Crepipatella) foliacea, Brod. loc. cit. pi. 28, f. 9. B. M. Cat. DOrb. Moll. p. 49, no. 419. (Pteste Gray.) ? + Crepidula Patagonica, DOrb. B. M. Cat. p. 48, no. 416, (Pteste Gray.) Comp. Crepidula lineolata, Desk, in Lam. An. s. Vert. vol. vii. p. 646, no. 11. To this formidable list of synonyms, Dr. Gray adds C. protea of DOrb. andD'Orbigny adds C. unguiformis, Brod. These shells appear however more nearly related to C. nivea, C. B. Ad. and C. unguiformis, Lam., to which last, the West Indian specimens of C. protea (B. M. Cat. Cub. Moll. p. 33, no. 396) probably belong. Some of the specimens marked C. protea by D'Orb. are perhaps dead shells of C. onyx. It will be observed that this species is distributed under two subgenera MAZATLAN UNIVALVES 273 by Messrs. Adams. No specific difference can be traced be- tween the Sandwich Island specimens, those from Mauritius, and the abundant forms from S. America. The species does not affect the Northern hemisphere. It is not quoted by C. B. Adams in his Panama list. The solitary specimens from Guinea, Mazatlan and California may have been imported. Of the two Larnarckian names, the first is chosen, although very imperfectly described from a single specimen in the collection of Mde. de Bandeville, because it well expresses the usual character of the species, and has been adopted by D'Orbigny. Long. 1*42, lot. 1'2, alt. '68. Hob. S. America, D'Orbigny. Mazatlan ; 2 large but dead specimens ; L'pool Col. Lower California; 1 dead specimen ; Major Rich. (C. Peruviana.) Peru, Dombey. Peru and Chiloe, Bern. Philippi. (1 sp.) Loander, Tarns. (C. patula) Otaheiti, Lesson. (C. strigata.) Valparaiso ; on Mytili, 3 6fm. ; Cuminq. (C. pallida.) Falkland Is. ; under stones ; Cuming. (C. arcuata.) Payta, Peru, D'Orbigny. (C. lineo- lata.) South Seas, Deshayes. Tablet 1353 contains a specimen, with attachments of two others on its back. 336. CBEPIDTJLA PDOESATA, Brod., var. BILOBATA. C. t. tenui, subcirculari, subdiaphand, albidd, scepe fusco radiatd sen maculata, ; vertice nucleoso globoso, satis magno, apice subdepresso, anfractibus rapide augentibus, vix extante, haud prominente, a margine valde remoto ; Icevi, sen striis incre- menti, interdum lamellis irregularibus ; hue et illuc vix radiatim striatd, seupropter sedem quasi costatd ; lamind tenui, bilobatd, lobd posteriori parvd, anteriori maxima, ad extremitates sinu- atd, apicem versus impressd, incrementi lineas manstrante. Calyptrsea dorsata, Srod. Proc. Zool. Soc. 1834, p. 38 : Trans. Zool. Soc. vol. i. p. 202, no. 20, pi. 28, f. 10. About a dozen young specimens of this species were found in the shell washings ; but some beautiful ? adult shells are in Mr. Cuming's Col. The form is intermediate between Crepidula and Crucibulum, the young state of which it greatly resembles. The lamina is attached by less than one half of its total length ; and the vertex is situated about half way up the height of the shell. The above diagnosis was written in ignor- ance of Broderip's species, which (with others) had been lost 274 MAZATLAtt UNIVALVES in Mr. Cuming's Museum, but which lie has allowed me to restore from the overwrought figures in the Transactions. It is closely related to some forms of C. dilatata, jun. The mode of growth in the young shell is as in C. nivea, &c. The vertex is rather large, '02 in. or upwards across, Velutina- shaped, smooth, with a rather sunken apex and rapidly increas- ing whirls. On commencing the permanent form, it spreads a film over the base of the spire and a very large margin all round. The deck commences at a considerable angle from this film, first as a marginal line, then gradually developing till the lobes are formed. The vertex is rather prominent, but not separate from the body of the shell. Some of the shells are more solid than Mr. Cuming's adult specimens ; and further agree with the typical C. dorsata in being of a yellowish cast, with the deck rather brown. The subdiaphanous white specimens are sometimes spotted with chesnut. The largest Mazatlan specimen, (the margin of which is dentated) mea- sures . . long. '33, lat. '37, alt. '12. Mr. Cuming's sp. . '6, *56, '27. Hal). (C. dorsata.) St. Elena; on dead shells, in sandy mud, 6 fm. ; Cuming, (teste Brod. : Valparaiso, teste Mus. Cum.) (Var. bilobata.) California ; Mus. Cuming. Mazatlan ; ex- tremely rare, jun., on shells ; L'pool Ccl. Tablet 1354 contains 5 sp. of different ages. In the first, '03 across, the margin is formed, but not the deck : in the second, the deck line has commenced. 337. CREPIDTJLA EXCAVATA, JBrod. C. t. tenuiore, Icevi, oblongd, latere dextro expanso, sinistro convexo ; alba, castaneo varie maculatd, intus nitente ; vertice valde adunco, a margine maxime separato, dextrorsum valde spiraliter contorto ; nucleo satis magno, discoidali, satis inflato, apicem depressum monstrante, regulariter crescente ; habitu incrementi subspirali, obliquo, regulari ; septo tenuiori, vix opaco, ad marginem lineas incrementi monstrante. vix in mcdio ; haud aliter sinuato ; oblique et profunde sito, cavitate magnd ad verticetfi ascendente ; limbo acuto. Calyptrsea (Crepidula) e. Brod. in Proc. Zool. Soc. 1834, p. 46 : Trans. Zool. Soc. vol. i. p. 205, no. 29, pi. 29, f. 7MtilL Syn. Nov. Test. Viv. p. 150. Crepidula e. Desk, in Lam. An, s. Vert. vol. vii. p. 649, no. 19. C. _B. Ad, Pan. Shells, p. 226, no. 345. MAZATLAN UNIVALVES 275 This beautiful and rare species combines the form and habit of growth of the Atlantic C. porcellana, Linn, with the very remote apex of C. adunca. This character also separates it from C. arenata, Brod. (found at S. W. Mexico, P. P. C., but not at Mazatlan,) to some forms of which it bears a close resemblance. C. arenata occasionally develops an apical hole within, (Mus. Cum.) : but is never seen with the very oblique growth of this species. The nucleus is like a regular, somewhat tumid Plan- orbis ; shewing the whirls within, and measuring about '02 in. across. The enlargement is regular, and the young shell has exactly the characters of the adult, except that the apex, though, separate, is nearer the margin. Only two very young specimens and one adolescent were found in the Mazatlan collection ; a larger one, probably from the same collection, was obtained from a shop : and some very fine ones are in the Cumingian Museum. The smallest specimen is ' 12 in length ; the largest long. '95, lat. '64, alt. '35. Sab. Real Llejos, Cuming, teste Broderip : (but Gulf of Cali- fornia, teste Mus. Cum.) Panama, 1 sp. C. B. Adams. Mazatlan ; extremely rare, jun. on Spondylus ; Upool Col. Tablet 1355 contains a young sp. 1356, an adolescent sp. 338. CEEPIDULA ADUNCA, Sow. Tank. Cat. no. 828, App. p. vii. (Crypta a.) H. & A. Ad. Gen. i. 369. = Crepidula solida, Hinds, Voy. Sulph. Moll, p, 53, no. 218, pi. 16, f. 7, 8. (Crypta s.) H. $ A. Ad. Gen. i. 369. = Crepidula rostriformis, Gould, JExp. Shells, 1846, p. 14. Jun. = Crepidula rostrata, C. S. Ad. Pan. Shells, pp. 235, 320, no. 353. (Crypta r.) H. Sf A. Ad. Gen. i. 369. Jun. var. = Crepidula uncata, Mke. in Zeit.f. Mai. 1847, p. 184, no. 34. = Crepidula incurva, var. P. P. C. Cat. Prov. Garnotia solida, Gray, Gen. 'Moll. IB. M. p. 117. The very remarkable form of this species has attracted the attention of six celebrated naturalists, each of whom have im- posed upon it a separate name. The first three specific names are identified from the types ; the other two from the very accu- rate descriptions given. The irregular corrugations of C. B. Ad. are abnormal, as are also the three ridges of MenJce. Normally, the shell is quite smooth, with a rather glossy epidermis ; with 276 MAZATLAN UNIVALVES the colour lighter than in C. incurva, and disposed to break up into spots ; shaped like Emarginula rosea, with a very recurv- ed, distant and projecting vertex, a short, deeply sunk and slanting deck, and a hole abov^ it passing up the spire. The characters are like some of the forms of Cr. incurva intensified ; and are subj ect to considerable variation. The mode of growth is as in that species ; but the planorbiform vertical whirls are even smaller, (about '01 across) with the apex deeply sunken. The smallest specimen is *15 in length ; the largest found measures long. '84, lot. '62, alt. '46. Aflatsp. '62, '48, "18, The shortest-decked specimen measures '16 from deck margin to the posterior, '39 to the anterior end, with an apical projec- tion of *14. Hob. Bodegas, California ; attached to dead and living shells and to each other, 6-10 fm. ; Hinds. Straits of De Fuea, G-ould.Sta, Barbara, Col. Jewett Panama, extremely rare, C. B. Ad. Mazatlan ; extremely rare ; Upool Col. Tablet 1357 contains 2 sp. very young. 1358, 1 sp. flat, margin extended. 1359, 1 sp. compressed, dark brown. 1360, the largest sp., twisted growth, slightly ribbed and corruga- ted. 1361, 1 sp. pale flesh colour. 339. CEEPIDULA INCUBVA, Brod. Calyptrsea (Crepidula) incurva, Brod. Proc. Zool. Soc. 1834, p. 40 -.Trans. Zool. Soc. vol. i. pi. 29, f. QMilll. Syn. Nov. Test. Vw. p. 150. Crepidula incurva, B. M. Cat. TfOrl. Moll. p. 49, no. 421. C. B. Ad. Pan. Shells, p. 228, no. 347 (Crypta i.) H. $ A. Ad. Gen. i. 369. =- Crepidula hepatica, MenJce, (non Desli. nee C. B. Ad. nee Krauss,) Zeit.f. Mai. 1847, p. 184, no. 33. This species is known normally by the sharp longitucMaal ridges on the back, which are not dependent on the attachment, being regular in growth, and conspicuous when adherent OIL smooth shells. It is much smaller than C. onyx, of a deeper chocolate brown colour, convex, with the beak very prominent, smooth and black as in C. rugosa, Nutt. The epidermis is rather thin and deciduous. There are however so many speci- mens in which one or other of these characters pass away, that MAZATLAN UNIVALVES 277 it is not impossible that further researches may prove their identity. The vertex of C. incur va is discoidal and smooth, as in C. onyx, rather smaller, and more hidden by the subsequent growth of the shell. The earlier portion is very convex, smooth, nearly black. It develops ridges rather suddenly, strong enough to serrate the margin, which is then beautifully varie- gated with horn colour and tortoiseshell, and frequently rather spreading. As the shell advances, the ribs often pass away, leaving traces however by which the species may generally be recognized. The deck occupies a larger or smaller proportion in different specimens, and is more or less sunken, rarely developing a slight hole under the vertex, approaching C. adunca. The spreading specimens generally assume a lighter colour, like C. onyx, which in mode of growth and in the character of the deck they closely resemble. A large propor- tion of the shells are truncated in front, as though from living against a rising surface. The youngest specimen is '07 in length ; a large one, approaching C. onyx, and living like an operculum in the mouth of Uvanilla unguis, measures long. '9, lat. '6, alt. '25. A convex, spreading sp. '92, *67, *4. A narrow sp. '82, '46, '33. Hob. St. Elena and Xipixapi ; on dead shells in sandy mud 6 10 fm. ; Cuming. Payta, Fontaine. Panama ; on living Gasteropods at and near low water mark, and on each other, common ; C. 13. Adams. : San Bias, Capt. Wendt, (Menke.) Mazatlan ; on shells and on each other, not uncommon ; ISpool Col. Characters approaching C. onyx. Tablet 1362 contains the specimen in U. unguis. 1363, 1 sp. nearly smooth, singular!^ indented. 1364, 3 sp. scarcely striated, flat. 1365, 3 do. convex, laterally compressed. 1366, 3 sp. slightly striated, flattened, light coloured. 1367, 3 do. very dark. 1368, 3 do. more striated, light colour. Normal state. Tablet 1369 contains 3 sp. very young. 1370, 6 sp. different ages, deck margin deeply angulated. 1371, 4 sp. slightly do. 1372, 4 sp. slightly sinuated 1373, 4 sp. flattened, broad. 1374, 7 do. lighter colour, deck margin nearly straight, direction slanting. 1375, 6 sp. deep, compress- ed growth. 1376, 4 sp. twisted, vertex at the left. 1377, 3 do. vertex at the right. 1378, Columbella fusca, with Crepidula incurva, shewing attachment. 1379, Pisania hsemastoma, with July 1856. aa 278 MAZATLAN UNIVALVES 2 Cr. incurva in situ, one on the other. 1380, 2 sp. with Bryozoa and Serpula. Aberrant specimens. Tablet 1381 contains 2 sp. deck thin, as in C. nivea. 1382, 1 sp. verv convex, light coloured. 1383, 2 sp. deck variable in length. 1384, 5 sp. margin irregular. 1385, 4 do. diseased. 1386, 3. sp. form approaching C. adunca, jun. 1387, 5 do. adult. 340. CREPIDULA ONYX, Sow. C. t. solidiore, plerumque lamellis, ad marginem scepe, extus rare apparentibus, instructed ; epidermide olivaced copiose in- dutd, irregulariter lamellosd, haud nitente ; habitu incrementi plerumque recto, seu incurvato, haud spirali ; planatd, sen in- terdum convexd ; colore kepatico, splendente, interdum nigriore, rare livido-carneo ; vertice nucleoso parvo, l&vi, discoidali, apice celato, prope marginem plerumque centraliter sito, s&pissime ad marginem vecto et detrito ; testa juniore subcorned, castaneo maculatd, haud nigrd ; septo interno solidiore, opaco, albo, striulas incrementi nisi marginem versus haud monstrante, margine plus minusve intus angulato, nee antice nee pottice distincte sinuato. Sow. Gen. Crepidula, f. 2, Crypta onyx, H. fy A. Ad. Gen. \. p. 369. = Crepidula Phepatica, (7. B. Ad. Pan. Shells, p. 227, no. 346. (teste sp. typ. in Mus. Cum.) : non Menke in Zeit. f. Mai. 1847, p. 184, no. 33. ? = Crepidula hepatica, Desk. JEnc. Meth. Vers, 1830, vol. ii. p. 26, no. 7 : Lam. An. s. Vert. vol. vii. p. 646, no. 12. (Crepipatella h.) H. $ A. Ad. Gen. i. 369. ? = Crepidula hepatica, Krauss Sudafr. Moll. p. 69, no. 3, pi. 4, f. 12 a, b.Dkr. Ind. Moll. Guin. p. 34, no. 92, pi. 5, f. 4, 5. = Calyptrsea amygdalus, Val. Voy. Ven. pi. 15, f. 3. Var. ? = Crepidula contorta, Mke. Zeit. f. Mai. 1851, p. 35, no. 121, (non Quoy fy Gaim.) Jun. = Crepidula Cerithicola, C. S. Ad. Pan.'Skells, pp. 225,, 320, no. 343. Comp. Crepidula rugosa, Nutt. in Jays Cat. p. 107, no. 3043, bis.- Proc. Zool. Soc. 1856. (Crypta. r.) H. $ A. Ad. Gen. i. 369. Whether Deshayes described his C. hepatica from a Pacific or African shell is not known ; and whether the two are identical has not yet been ascertained, the African specimens being generally too much worn for comparison. Krauss' var. com- MAZATLAN UNIVALVES 279 planata appears exactly to correspond with the Pacific shell, to which it is referred with certainty by DJcr, 9 with unwilling doubt by C. B. Ad. The shell quoted by him from Wee. appears (with hardly a doubt) to be C. incurva. The C. rugosa, Nutt. referred to this species by Jay, agrees in almost all respects ; but differs in the epidermis which though somewhat lamellar is glossy, never shaggy ; and in the young shell which is of a very dark colour, with a Velutina-shaped vertex. These most closely related species are however referred to different subgenera by Messrs. Adams. C. onyx begins life like a swollen Planorbis, about '013 across, with the apex more or less concealed. It increases as in C. nivea, leaving the vertex free, submarginal, and generally medial, the shell increasing in the plane of the vertex, so that the latter can only be seen when the shell is set on its side. At this period the body of the shell is light horn-coloured, with copious stains of tortoiseshell. As it increases, it develops the lamellose structure and shaggy epidermis of C. nivea, so that the light-tinted specimens of this can with difficulty be separated from the dark specimens of the other, the character- istic vertices being generally lost in the onward progress of the shell. The character of the deck, similar in the young shell, is strikingly different in the adult ; for while it develops the central angle, more or less, the extremities are not sinuated ; and the substance does not display striae of growth, except close to the margin, the principal part being opaque and uniform. In this it closely resembles C. incurva, from some varieties of which it can scarcely be distinguished. The outer surface very rarely develops faint longitudinal undulations, (never sharp ridges as in C. incurva) probably from adher- ing to ribbed shells. Even in specimens with the epidermis very fresh, it is often rubbed smooth at different angles on the back, Pfrom adhering to pebbles rolled by the tide. The inside is richly lustrous, generally brilliantly hepatic, rarely blackish brown, most rarely of a light flesh colour. The smallest (imperfect) specimen is '07 long ; a flat sp. (convex when young) measures long. 1*04, lot. *7, alt. '1. A twisted sp. 1'36, '9, '6. The largest sp. 2'2, 1'3, '6. This shell weighs '66 oz., and displays a thickness of laminae amounting at the umbo to '43 in. Hob. Panama; on Strombus Peruvianus and other shells, rare ; C. B. Adams. Mazatlan ; very rare, on shells, &c. 280 MAZATLAN TTNIVALVES L'pool Col. [C. ? hepatica : Benguela and Loander, very common and variable, Tarns-. Tafel Bay and Natal, XraussJ] Tablet 1388 contains 3 sp. very young. 1389, 4 sp. different ages, finely grown. 1390, 2 sp. form approaching C. incurva ; one very dark. 1391, 1 sp. with irregular ridges, passing to the form Lessonii. 1392, 1 sp. twisted, apex lateral. 1393, the largest specimen. 1394, 1 sp. light coloured, slightly rayed with darker. 1395, 1 sp. very light coloured, beginning con- vex, suddenly becoming flat and slightly rayed in the middle. Tablet 1396 contains 2 young sp. var. Lessonii, probably belonging to this species, but perhaps to C. nivea. ^ 341. CBEPIDULA NIVEA, C. B. Ad. Cr. t. ellipticdj subrotundatd, seu maxime elongatd ; tenui, sew incrassatd ; intus nived, lineis castaneis radiantibus scepe ornatd; sublcevi, seu irregulariter concentrice plus minusve rugosd, seu lamellis extantibus varie instructd ; limbo acuto, seu maxime planato, lamelloso ; epidermide copiosd irregulari- ter lamellosd ; superficie seu striulis coneentricis seu (sub lente) rugulis radiantibus varie ccelatd ; habitu incrementi vix spirali ; vertice nucleoso, minimo, Velutince simili, apicem monstrante, castaneOj rare albo, rugis coneentricis conspicuis instructo, satis prominente, spiraliter subito augente, dextrorsum deflecto, amar- gine vix remoto, scepe ad marginem vecto et detrito ; septo plus minusve in medio angulato seu sinuato, ad sinistram partem plus minusve prof unde, ad dextr amp arum sinuato, tenui, lineas incrementi, kaud lineam centralem monstrante. C. B. Ad. Pan. Shells, 1852, pp. 234, .320, no. 351 : diagn. auct. (Crypta n.) H. $ A. Ad. Gen. i. 369. + Calyptrsea (Crepidula) Squama, Brod. Proc. Zool. Soc. 1834, p. 40: Trans. Zobl. Soc. vol. i. p. 205, pi. 29, f. W.Miill. Syn. Nov. Test. Viv. p. 151. (Crepidula s.) Lam. An. s. Vert. vol. vii. p. 648, no. 16. C. B. Ad. Pan. Shells, no. 649, p. 229 (lanacus s.) H. fy A. Ad. Gen. i. 370.-^? = Crepidula G-oreensis, Mice. Zeit.f. Hal. 1851, p. 36, no. 124. + Crepidula striolata, Wee. Zeit.f. Hal. 1851, p. 35, no. 123. 4- Calyptrsea (Crepidula) Lessonii, Brod. I&oc. Zool. Soc. 1834, p. 39 -.Trans. Zool. Soc. vol. i. p. 204, pi. 29, f. 5 Mull. Syn. Nov. Test. Viv. p. 149. (Crepidula L.) Lam. An. s. Vert. vol. vii. p. 649, no. 20. (lanacus L.) H. $ A. Ad. Gen. i p. 370, MAZATLAN UNIVALVES 281 = Crepidula unguiculus, var. Brod. in Mus. Cum. [lanacus unguiculus, Sow. ?ubi) H. fy A. Ad. Gen. i. 370. ? = Crepidula Patagonica + C. protoa, D'Orb. (pars,) B. M. Cat. Moll p. 48, no. 416, 417. Comp. Crepidula Navicelloides, Nutt. in Jay's Cat. p. 107, no. 3035, (Upper California.) Comp. Crepidula explanata, Gould, Cal. Mex. Shells, p. 4, pi. 14, f. 7. = Calyptra?a perforans, Vol. Voy. Yen. 1846, pi. 24, f. 9, 9 a, b. [The author seems to imply that the creature burrows : the specimen represented however has evidently been developed in the hole of a Lithophagus.] = C. exuviata, Nutt. in Jays Cat. p. 107, no. 3027. This creature, when flat and finely grown, is the C. squama of Brod. The same shell, when coarsely grown, more convex and without brown stripes, is the C. nivea of C. B. Ad. When the Ia3 r ers of which C. nivea is composed, instead of lying regularly one over the other, are slightly prominent, it becomes the C. striolata, Mke. When they are drawn forwards and project, it becomes the C. Lessonii, Brod. The name of Prof. Adams is retained, in preference to the prior ones of Broderip and Menke, as representing the normal condition of the shell. The name C. unguiculus has priority, but does not appear to have been published. Among the specimens marked C. protea and C. Patagonica by D'Orb. in his collections, there are several which seem to belong to this species ; others to C. onyx, &c. v. supra. Both are referred by Dr. Gray to C. dilatata, (B. M. Cat. D'Orb. Moll. p. 49.) C. nivea begins life as a minute Velutina-shaped body, with a sunken apex and coarse concentric folds. When this has grown to about '015 across, it suddenly enlarges itself, throws a columellar lip over the base of the shell, raises a more or less prominent margin round it, so as to surround the vertex, and commences its septum at an angle from the columellar lip varying from about 90 at the posterior to 130 at the anterior end. The smallest shell found measures '045 in length, on which these stages are distinctly traceable. The septum is at first straight, then angulated in the middle, lastly with an anterior sinus. In the 'squama' stage, it appears as a very thin flat shell ; with the vertex generally lustrous brown, sometimes white ; from this radiate a greater or less number of brown line^, sometimes more or less broken into dots, gradually losing 282 MAZATLAN UNIVALVES themselves in the white texture of the shell, sometimes re- appearing at the margin, sometimes altogether absent. Very rarely a rich lustrous brown is developed inside, as in C. onyx, shading into a sea-weed green. The shell is covered with a copious yellowish-green epidermis, which lies in a fringe round the sharp margin. Under this, the surface presents concentric striae of growth, and very fine longitudinal corrugations. Either of these however may disappear, or be developed at the ex- pense of the other. The vertex is either in the margin, or as much as '08 removed from it ; it is not imbedded in the sur- face of the shell as in C. unguiformis, but is slightly prominent, displaying its rugose folds. Both these and the vertex itself are often rubbed off. In its ordinary state, the texture has a tendency to run into layers. The epidermis does the same, the layers being in shreds and very copious. These layers in the adult are often continued to the margin, making it broad and flat. At other times they stand out more or less on the back of the shell. Sometimes the shell advances longitudinally, making layers at more or less regular intervals, becoming then the aberrant form C. Lessonii ; which is however connected by such gradual links, through C. striolata, with the typical C. nivea, as not to admit of separation. In this form, (common in some places, but extremely rare at Mazatlan, the vertex is generally left behind and rubbed off: in the only S. American specimen in which it was found, it exactly agreed with the remarkable character of C. nivea. The specimens in Mus. Cuming from Vancouver's Str. (without authority,) are large and spreading ; with the apex small and ribbed as in C. nivea, but white. Of the shells collected by Mr. Nuttall at Monterey &c., some want the vertex, but otherwise resemble C. nivea : one very young specimen however has a specifically different vertex, more resembling Cr. fornicata, &c. The C. explanata of Gould is probably a variety of the Monterey shell, caused by living in the hole of a Lithophagus ; similar forms of C. nivea being found among the Mazatlan shells. It differs in the cancellated structure between the laminae, which however is not seen in the Cumingian specimens. In its young state, the shape is normal. If the species should prove distinct, the name of Gould must take the place of the prior names of Nutt. and Val., the former not having been described, and the latter representing an untruth. The growth of C. nivea is rather straight, after the nuclear portion is completed, with the vertex submedial or directed MAZATLAN UNIVALVES 283 to the right : sometimes however it is rather spiral, resembling C. aculeata. The deck margin generally has a more or less re-entrant angle in the middle. This however is sometimes rounded ; sometimes nearly straight. The sides are either straight or lobed. The anterior sinus is either very deep or scarcely perceptible. The sinuated part is sometimes callous. The surface of the deck is generally thin, displaying fine strise of growth. The inner surface is either very glossy, or (under the microscope) most finely corrugated. The coloured lines are extremely variable in the same specimen, being often conspicu- ous when young and suddenly ending. Very young shells were extremely rare. The animal hollows out a place for itself on Patella Mexicana, &c. ; but no shelly deposit has been ob- served. The largest sp. measures long. 1*95, lot. 1*35, alt. '46. Aflatsp. 1-46, 1'02, '14. A rounded, convex sp. '77, '68, An elongated sp. 1*35, '6, ,, Sp. a. Deck margin from vertex '77, from opposite end Sp. b. '53, '8. Hab. Mazatlan ; abundant ; ISpool Col. (C. nivea) Panama ; under stones near low water mark, not common ; C. B. Adams. (C. squama) Panama, Cuming : do. under stones and in dead shells near low water mark, not common ; C. B. Adams. (C. Lessonii) Isle of Muerte ; under stones at low water ; Cuming, Panama, do. common ; C. J3. Ad- ams. Vancouver's Straits, Mus. Cuming. Form squama. Tablet 1397 contains 8 sp. very young, of different sizes. 1398, 17 sp. different ages, striped. 1399, 5 sp. different ages, colour not conspicuous. Form nivea, normal. Tablet 1400 contains 6 sp. finely grown, with brown rays outside. 14)1, 6 sp. do. wfthout brown rays. 1402, 7 sp. with broad laminated margin ; one sp. measuring 1*7 outside, and 1*38 within ; another, measuring '97 within, has an apical margin '32 across. 1403, 4 sp. rough, laminated outside. Form striolata. Tablet 1404 contains 4 sp. beginning as squama, developing a few slight ridges. 1405, 5 sp. form nivea, irregularly developing ridges. 1406, 6 sp. ridges more deve- loped ; one being convex and closely ridged from the begin- ning. 1407, 2 sp. Lessonii-forrQ. developed, laminae close. 1408, 3 do. very irregular. (The two larger sp. are from a dealer, locality unknown, but among other Mazatlan shells.) 284 MAZATLAN UNIVALVES 1409, 1 sp. finely developed, with coloured rays, laminae con- centrically striated. Aberrant specimens. Tablet 1410 contains 1 sp. longitudin- ally ribbed (from adherent surface.) 1411, 7 sp. margin irregular. 1412, 3 sp. margin curved. 1413, 3 sp. flat and recurved, form of C. unguiformis. 1414, 6 sp. posterior margin expanded. 1415, 3 sp. subspiral, approaching C. aculeata. 1416, 1 sp. deck elongated. 1417, 3 do. deck very short. 1418, 3 do. colour developed inside, brown passing into green. 1419, 1 sp. shewing under layer of deck, striated. 1420, 1 do. dis- eased. 1421, 1 do. deck solid, as in C. onyx. 1422, 1 do. flat, concentric striae conspicuous. 1423, 3 do. longitudinally cor- rugated. Tablet 1424 contains a portion of Spondylus calcifer, pre- sented by B-, D. Darbishire, Esq. containing in situ 4 sp. Petricola robusta, 1 Cumingia, 2 Lithophagus plumula, 1 Gas- trochaena truncata, and 1 Crepidula nivea. This is greatly elongated, 1 '55 by '72, much arched, and with very numerous layers. Its position in a burrow of Lithophagus has preserved the apex from detrition. 1425, 1 sp. still more elongated, from the burrow of a Lithophagus in Chama, closely resembling C. explanata, Gould. Specimens shelving deck margin. Tablet 1426 contains 3 sp. ainus slight, center more or less deeply angulated. 1427, 6 sp. sinus deep, center nearly straight, more or less angulated or sinuated. 1423, 1 sp. with abnormal central ridge. Tablet 1429 contains 2 young shells which probably belong to this species, though the apex has been rubbed smooth. 342. CEEPIDULA PTJNGUIFOBMIS, Lam. Patella crepidula, -Linn. Syst. Nat. p. 1257, no. 752. Dillw. Descr. Cat. p. 1021, no. 13. Crepidula unguiformis, Lam. An. s. Vert. vol. vii. p. 642, no. &.Brod. Proc, Zool. Soc. 1834, p. 39.-* C. B Ad. Pan. Shells, p. 230, no. 350. (lanacus u.) H. & A. Ad. Gen. i. p. 370. Crepidula Italica, Defr. Diet. So. Nat. vol. xi. p. 397. ^ Crepidula plana, Say, Journ. Ac. Nat. Sc. Phil. vol. ii. p. 226. (teste Gould fy C. B. Ad. non Desk.) Comp. Patella Goreensis, Gmel. p. 3694. Dillw. Descr. Cat. p. 1030, no. 12. (Crepidula G.) Desk, in Lam. An. s. Vert. MAZATLAN UNIVALVES 285 vol. vii. p. 645, no. 10. Wee. in Zeit. f. Hal. 1851, p. 36, no. 124. (Crypta G.) H. $ A. Ad. Gen. i. p. 369. (Le Jenac,) Adans. Coq. de Sen. p. 41, pi. 2, f. 10. For other references, v. C. B. Ad. loc. cit. The late lamented and most accurate Prof. Adams, who in all other instances has created fresh species sooner than allow that the same shell could be common to the Atlantic and Pacific waters, has here, and here only, departed from his theory, and has quoted the above shell from the following six zoological provinces, to which we must now add a seventh : 1. Mediterranean 2. East coast of North America, North of Cape Cod. 3. Do. South of the Cape. 4. The Carribean waters. 5. West tropical America. 6. S. W: temperate region. Also fossil in Italy, Morea, Bordeaux, Dax and Tour- aine, Desk. "Fossil nel PiacSntine e nel Sanese," Broc. And yet it is not impossible that in this his only instance, he may be in error ; and that the shells he has quoted from Panama (with those of Brod. from Panama, perhaps from Chiloe,) are varie- ties of his own C. nivea ; as the shells of D'Orbigny, quoted by him under this species, are said by Dr. Gray (B. M. Cat. D'Orb. Moll. p. 49, no. 418,) perhaps not correctly, to be varieties of C. dilatata. The form either of margin or of deck is not to be relied on in shells of this type. On examining however the young shells classed as C. nivea, it was found that some of them differed from the rest in the following particulars. 1. The spiral vertex is much larger, being, in a shell '095 long, '025 across. 2. It is smooth, not concentrically wrinkled. 3. It is sunken in the produced mar- gin of the shell, not prominent as in C. nivea. 4. It expands so evenly, that it is difficult to fix upon the point at which the spiral part ends. 5. The large spire shews conspicuously through the columellar lip, (at an angle from the deck, as in C. nivea.) 6. The epidermis appears much thinner. In all other respects, its mode of forming the deck, the shape of its margin, the white colour often streaked with brown, and the tendency to grow in layers, it agrees exactly with the larger species. Whether these characters are peculiar to the shells of the ordinary form Cr. unguiformis, which dwells in dead shells and is therefore liable to transportation through all seas, I cannot tell, as the vertices are rarely perfect, being lost at the advance of the shell. It is however worthy of examination by those who have access to young shells on the Atlantic coasts. That two shells, so very similar and similarly variable in the 286 MAZATLAN UNIVALVES adult state, should be so different in their early stage, is very remarkable. A series of specimens from the inside of a West African Pinna, of which the youngest is only '04 long, agree exactly with the Mazatlan specimens now described. The largest, 1*18 in length, would certainly have been called C. squama if from Panama, though the epidermis is thinner than in the ordinary Mazatlan specimens. They go through the same changes of colour, deck margin, &c. as C. nivea ; and if they had been born in an empty Cowry would prooably have deve- loped into the genuine C. [unguiformis. As it is, they are probably the C. G-oreensis,* a species which, according to Dillwyn, has a tendency (like C. nivea) to develop foliations. Whether the specimens quoted by Menke as C. Goreensis belong to this species or to C. squama, cannot be told without an examination of the vertex. Shells of exactly the same species, some extremely young and well formed, others of the true C. unguiformis shape, circular and elongated, were found in dead East Indian Cowries from Singapore The species may abound at Mazatlan ; but as almost all the vast numbers of shells sent were perfectly fresh, there is no knowing what the dead ones contained. The largest Mazatlan shell with the apex perfect measures long. '12, lat. '08, alt. '02. Others, which have lost the apex in growth, may belong either to this species or to C. nivea. JIab. Mediterranean, Africa, Singapore, North and South America, East and West ; fossil in tertiary strata ; v. supra. Callao, Peru, very fine, in dead shells, B. M. Col. D'Orbigny, not in Cat. Mazatlan ; extremely rare, in dead shells, &c. ; L'pool Col. Tablet 1430 contains 3 sp. young. 1431, an adult sp. in empty Trivia radians. GENUS CKFCIBULUM, ScJium. Crucibulum, ScJium. Ess. no. 8, 1817 : Gray, *Proc. Zool. Soc. 1847, p. 157, no. 270 ~H. $ A. Ad. Gen. vol. i. p. 365. Dispotsea, Say, Journ. Ac. N. S. Phil. vol. iv. 1124 Calypeopsis, Lesson, 1830, Brod. 1834. * The young of Cr. fornicata, as appears from specimens from Staten Island m the collection of R. M' Andrew, Esq. is of the type Cr. Goreensis, Q-mel. but with only one large tumid whirl (as in Crucibulum imbricatum,) lying imbedded in the normal portion. Inside with first deck at an angle with the succeeding. MAZATLAN UNIVALVES 287 Distinguished by its complete cup, attached at its vertex, and generally more or less along one side. Great confusion attends the synonymy of the species, the names extinctorium, rugosa, imbricata & auriculata having been used by different authors to denote very different species. _J. 343. CBUCIBTJLUM IMBEICATUM, Sow. CalyptraBa imbricata, Sow. Gen. f. 5. Desk, in Lam. An. s. Vert. vol. vii. p. 636, no. 33. C. (Dyspotsea) imbricata, Mke. in Zeit.f. Mai. 1847, p. 185, no. 36. C. (Calypeopsis) .imbri- cata, B. M. Cat. I)' Orb. Moll. p. 47, no. 409. Jun. = Calyptrsea imbricata, Brod. Proc. Zool. Soc. 1834, p. 36 -Trans. Zool. Soc. vol. i. p. 193, no. 7, pi. 27, f. 7. C. B. Ad. Pan. Shells, p, 222, no. 336. = Crucibulum scutellatum, Gray, in Mus. Cuming.= Patella scutellata, [Gray in] Wood, (B. M. ms.) Ind. Test. Suppl. 1828, p. 26, pi. 8, f. 4 * = Calyptrsea (Calypeopsis) rugosa, Less. Voy. Coy. no. 158: Guer. Mag. Zool. 1839, pi. 2. (Non. Desk, in Lam. An. s. Vert. vol. vii. p. 637, no. 34: = C. lignaria, Brod.) Var ? = Crucibulum Pimbricatum, var. Broderipii, Proc. ZooL Soc. June 1855. = Calyptrsea (Calypeopsis) rugosa, pars, B. M. Cat. DOrb. Moll. p. 47, no. 408. = Calyptrsea auriculata, P. P. C. Cat. Prov. (non Chemn.) + "Calyptrsea extinctorium?" Sow. Gen.\ f. 3. (Non Lam. An. s. Vert. vol. vii. p. 622, no. 1.) Crucibulum extinctorum, H. $ A. Ad. Gen. i. 366. = Calyptrsea rugosa, Vol. Voy. Ven. pi. 14, f. 1, (male.) Rve. Conch. St/st. pi. 144, f. 1. (Non Desk. loc. cit.) = Calyptrsea (Dyspotsea) dentata, Mke. in Zeit. f. Mai. 1847, p. 185, no. 35. (7. B. Ad. Pan. Shells, p. 221, no. 334. Jun. P= Calyptrsea auricularis, Desk, in Lam. An. s. Vert. vol. vii. p. 639, no. 40: Enc. Metk.Vers, vol. ii. p. 176, no. 18. (Non Patella auriculata, Chemn.) Comp. Calyptrsea ?P imbricata, var. Cumingii, Proc. Zool. Soc. June, 1856. =C. rugosa, pars, DOrb. loc. cit. (non Desh.) * Although this name was published first in time, yet as no description is given, and as the species cannot be recognized in the miserable figure, (as appear* from its having been overlooked by both Sow. & Brod.,) it does not appear entitled to priority. For the same reason the P. Peziza is laid aside, which may be the C. spinosa, Sow. t Of this shell no outside view is given ; but as the inside exactly corresponds with the C . imbricatum, while it is given as a distinct species, it is fair to conclude th at it is intended for the non-pitted variety of that form. 288 MAZATLAN UNIVALVES Comp, Calyptrsea gemmacea, Val. Voy. Ven. pi. 15, f. 2. [If the figure be accurate, this is a distinct, tubercled species : but it may be a small, conical, worn C. imbricata ; the quasi- tubercles being worn ribs.] The pitting of the intercostal spaces which seems to form the ground of separation between C. imbricata of Sow. and C. dentata of MJce. appears so very variable a character, that I have not ventured to regard them as distinct, The Mazatlan specimens (when in sufficiently fine condition to speak with certainty) are never wholly without pits : yet they are com- pletely irregular in their formation, often not being seen over a great portion of the surface ; not unfrequently appearing on one side only ; and very rarely traceable on the young shell. The species is normally rather solid, conical, with a very variable number (about 20) of stout rounded ribs, more or less spread- ing out at the margin. Fresh ribs are frequently formed in the intercostal spaces. When a fresh margin is formed below the palmations of the former one, a series of pits is produced. As the palmations are most developed in the adolescent state, so are the pits. They are rare in the older growth. Both ribs and intercostal spaces are finely, but irregularly indented with radiating corrugations. Fine radiating brown lines are often traceable outside, dotting the interior margin. The surface is generally rough and often covered with accretions; the vertex is rarely preserved. In Mr, Darbishire's collection, is a specimen with the animal matter dried within, and the young fry covering the principal part of the inner surface of the shell. These are shaped like Vanikoro, about "035 across ; with the apex flat, not sunken; with one tumid whirl exposed, and a very large umbilical area. The surface is concentrically and very finely furrowed. Most of the specimens have made a faint lip over the base, with an edge which is to commence the margin of the Patelliform shell ; but the cup is not begun. In this stage, the shell cannot be dis- tinguished generically from Crepidula. The nuclear whirls are turned laterally with the plane of after growth as in Capulus), perpendicularly to the base of the shell. The smallest specimen found in the adolescent stage is ' 17 across ; at which period it greatly resembles the young of Crepidula dorsata, the ribs not being developed. The cup is then semicircular, produced in front, adhering at the two separate margins. As it increases in size, the anterior margin bends round till it joins the posterior one, forming an entire cup, adherent almost to the MAZATLAN UNIVALVES 289 top. In this respect it differs from C. umbella, Desk. (Lam. An. s. Vert. vol. vii. p. 635, no. 30, = C. rudis, Srod. Proc. Zool. Soc. 1834, p. 35,) and the W. Indian form C. auriculata, Ckemn. Conch. Cab. vol. x. f. 1628-9 ; of which, though common in S. W. Mexico (P. P. CJ, not a single specimen was found in the Mazatlan collection. This latter species is generally longer, more spreading, of a lighter colour, and with the cup only adherent close to the vertex. The ribs are also less developed, and never pitted. The Calyptrsea auricularis of Deshayes may be the young of either species. The Mazat- lan shell is generally of a rich metallic brown, displaying a lighter or [deeper tint, sometimes nearly black ; rarely of a light grey or flesh colour ; occasionally tinted with green. The cup is always white, with transparent lines of growth. Its inner margin is scarcely flattened, and not angulated as in C. spinosa. When the creature lives on hard pebbles, there is generally an extremely thin shelly deposit : when on shells, a well marked excavation. Aflat, spreading sp. measures long. 2*1, lot. 1*8, alt. '65. A conical one ,, 1'28, 1*15, '72. Hal). Lower California, Major Rick. Bay of Magdalena, Gulf of California, Kellett^. W. Mexico, P. P. . Ac- apulco, Col. Jewett. Panama, very rare, C. B. Adams. Mazatlan ; not uncommon, on stones, dead shells, and each other ; Upool Col. Straits of Magellan ; [?] Mr. J. Robertson, B. M. Tablet 1432 contains a group of the fry, presented by E. D. Darbishire, Esq. Tablet 1433 contains 7 sp. very young. 1434, 5 do. young. 1435, 4 do. adolescent. 1436, 8 sp. shewing gradations of col- our from very light to nearly black. 1437. 4 sp. varying from very much to scarcely pitted ; margin much or scarcely palma- ted. 1438, 4 do. varying from very conic to spreading ; ribs few (20), with large palmations, or many (42), with very small ones. 1439, 1 sp. with a young one adhering. 1440, 2 sp. worm-eaten, cup diseased. 1441, 1 sp. on Ostrea Virginica. 1442, a stone with thin shelly attachment.' 1443, Uvanilla olivacea, with attachment of a Calyptrseid. 1444, A fragment of, primitive rock, with 5 sp. in situ : (presented by J. Hib- bert, Esq.) Aug. 1856. bb 290 MAZATtAfr UNIVALVES JL 344. CBUCIBULTJAI SPINOSUM, Sow. Calyptrsea spinosa, Sow. Gen. f. 4 : var ? f. 7. Lam. An. s. Vert. vol. vii. p. 636, no. 32.- Var. Brod. in 2Vaws. ZooZ. Soc. vol. i. pi. 28, f. 8. C. (Dyspotsea) sp. Jfyb. in Zeit. f. Hal. 1851, p. 36, no. 127. (Crucibulum sp.) H. & A. Ad. Gen. i. 366. -Patella Peziza, Wood, (B. M. ms.J Suppl. Ind. Test. 1828, p. 26. pi. 8, f. 3. = Calyptrsea tubifera, Less. Voy. Ven. pi. 14, f. 2. (Ordinary form, with, short, crowded spines.) "Dispolia" tubifera, Say, [probably a misprint,] in B.M. Cat. D'Orb. Moll. p. 47, no. 410. = Calyptrsea (Calypeopsis) auriculata, D'Orb. B. M. Cat. Moll. p. 47, no. 410. (JN~on Patella auriculata, Ckemn. v. Proc. Zool. Soc. June, 1856: eomp. C. umbrella, Desk.^C. rudis, Brod.) + C. (Calypeopsis) tennis, Brod. Proc. Zool. Soc. 1834, p. 36 : Trans. Zool. Soc. vol. i. p. 199, no. 9, pL 27, f. &Lcm. An. s. Vert. vol. vii. p. 637, no. 35. + C. (Calypeopsis) hispida, Brod. Proc. Zool. Soc. 1834. p. 37 : Trans. Zool. Soc. vol. i. p. 200, pi. 27, f. 10. Mull. Syn. Nov. Test. Viv. p. 144. Lam. An. s. Vert. vol. vii. p. 638, no. 36. Rev. Zool. Cuv. Soc. July, 1838.- Chenu, Lee. Elem. p. 144, f. 464. C. B. Ad. Pan. Shells, p. 221, no. 335. (Crucibu- lum h.) II. fy A. Ad. Gen. i. 366, f C. (Calypeopsis) maculata, Brod. Proc. Zool. Soc. 1384, p. 37 : Trans. Zojol. Soc. vol. i. p. 200, pi.. 27, f. 11. Mull. Syn. Nov. Test. Viv. p. 145. Lam. An. s. Vert. vol. vii, p. 638, no. 36 Rev. ZooL Cuv. Soc. July, 183& C. B. Ad. Pan. Shells, p. 223, no. 337. (Crucibulum m.) J?, ^ A. Ad. Gen. i. 366. (j^on C. maculata, Quoy fy Gaim. Voy. Astr. vol. iii. p. 422, pi. 72, f. 6, 9 :Lam. An. s. Vert. vol. vii. p. 628, no. 10. Comp. Calyptrsea rugosa, Desk. JEno. Metk. Vers, vol. ii. p. 173, no. 9 : Lam. An. s. Vert. vol. vii. p. 637, no. 34. (Non C. rugosa, Less. Voy. Coq. and Guer. Mag. : nee Vol. Voy. Ven.) = C. (Calypeopsis) lignaria, Brod. Pror. Zool. Soc. 1834, p. 36 : Trans^ ZooL Soc. vol. i. p. 198. no. 8, pi. 27, f. 8.Var. loc. cit. pi. 27, f. 8*. MAZATLAN UNIVALVES 291 f Calyptrsea (Calypeopsis) quiriquina, Less., B. M. Cat. D' Orb. Moll. p. 47, no. 407. ( = C. Byronensis, Gray in B. M.) + Calyptrsea (Calypeopsis) rugosa, pars solum, B. M. Cat. D' Orb. Moll. p. 47, no. 408 ; syn. plur. excl. Comp. C. (Calypeopsis) radiata, Brod. Proc. Zool. Soc. 1834, p. 36 -Trans. Zool. Soc. vol. i. p. 198, no. 6, pi. 27, f. 6. Lam. An. s. Vert. vol. vii. p. 635, no. 31. C. B. Ad. Pan. Shells, p. 223, no. 339. (ISTon C. radiata, Desk. 1836, An. s. Vert. vol. vii. p. 628, no. ll. = Galerus.) It is not surprising that this beautiful species has been described under such a variety of names, as the differences between individuals are patent at first sight ; their affinities only after a careful examination of a large multitude of speci- mens. And yet, though it would be most difficult to frame a 4 l**orJ]}tioTi that should include the whole and exclude neigh- bouring species, the general habit of growtn is such that it is not difficult to recognize, The Mazatlas specimens done prove the C. tenuis, C. hispida and C. rnaculata, of Brod. to be merely forms of growth of C. spinosa, Sow., which pass into one another by such gradual steps that they cannot be separ- ated even as varieties. The supposed differences observable in the Cumingian types are as follows, C. imbricata, olim (one of two shells differing specifically from each other, and each claiming the name of Brod. to the confusion of students ; an error now corrected) was the young state, before the cup is entirely formed : C. tenuis, the smooth, white, streaked form : C. hispida, the young state of the white shell, with small spines ; C. maculata (non Quoy), a rather older stage, smooth and spotted. The C. radiata, in most respects agreeing with C. spinosa, differs in the remarkable flattening of the cup, and in its greater separation from the margin. The C. quinquina of Lesson and D'Orbigny, (which is the C. Byronensis, Gray ms.) belongs to a Southern type which may be distinct-, though it has characters enough in common to make it not impossible that it is only a coarse variety. It is characterized by a more solid texture, light reddish brown colour, entire absence of spines, and a less angulated cup. To this form is referable, as an aberrant, variety, the C. lignaria of Brod., which is the C. rugosa of Desk, (not Less.) and in part of _D' Orb. These shells are always conical and Hipponi-