1 !> .0^ \ IMAGE EVALUATION TEST TARGET (MT-3) 1.0 I.I U£|28 25 2.2 lU 140 III— IIh ^ < 6" ^ tf) Photographic Sciences Corporation 33 WIST MA|t4 STRUT WMSTIR,N.>, MrOO (71«)l7i-4903 ji 4r CIHM/ICMH Microfiche Series. CIHIVI/ICIVIH Collection de microfiches. Canadian Inttituta for Historical IMicroraproductions / Institut Canadian da microraproductiona hiatoriquaa Technical and Bibliographic Notaa/Notas tachniquaa at bibiiographiquaa Tha Instituta has anamptad to obtain tha baat original copy availf bla for filming. Faaturas of this copy which may ba bibliographically uniqua, which may altar any of tha imagaa in tha raproduction. or which may significantly changa tha usual mathod of filming, ara chackad balow. HColourad covara/ Couvartura da coulaur r~| Covara damagad/ D D Couvartura andommagia □ Covars rastorad and/or laminatad/ Couvartura raatauria at/ou pallieulia r~~| Covar titia miaaing/ La titra da couvartura manqua Colourad mapa/ Cartaa gtegraphiquaa an coulaur □ Colourad ink (i.a othar than blua or black)/ Enera da C'.4ulaur (i.a. autra qua blaua ou noira) r~n Colourad plataa and/or illustrations/ D Planehas at/ou illuatratlons an coulaur Bound with othar matarial/ RalM avae d'autraa dooumants Tight binding may eauaa shadows or dittortion along intarior margin/ Laraliura sarria paut causar da I'ombra ou da la distorslon la kmo da la marga intiriaura Blank laavas addad duriny rastoration may sppaar within tha taxt. Whanavar possibla. thasa hava haan omittad from filming/ II sa paut qua oartainaa pagaa blanohaa ajoutiaa lors d'una rastauration apparaiaaant dana la taxta. mais, lorsqua eala Mait possibla, eas pagaa n'ont paa «t* filmiaa. 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Tl tc □ Colourad pagaa/ Pagaa D Pagaa da coulaur Pagaa damagad/ Pagaa andommagiaa Pagaa rastorad and/oi Pagaa rastaurAas at/ou pallicuiias Pagaa discolourad, stainad or foxai Pagaa dicolorAas. tachatias ou piquias Pagaa dataehad/ Pagaa ditachAas Showthrough> Transparanea Quality of prin Quality inAgaia da I'imprassion Includas supplamantary matarii Comprand du matirial supplAmantaira Only adition availabia/ Sauia Adition disponibia r~~1 Pagaa damagad/ p~| Pagaa rastorad and/or laminatad/ Pagaa discolourad, stainad or foxad/ Pagaa dAcolorAai r~~| Pagaa dataehad/ r~7] Showthrough/ r~1 Quality of print varias/ |~~| Includas supplamantary matarial/ r~l Only adition availabia/ Pagaa wholly or partially obscurad by arrata slips, tissuas. ate. hava baan rafllmad to ansura tha bast possibla imaga/ Laa pagas totalamant ou partiailamant obscurcias par un fauillat d'arrata, una palura, ate., ont AtA filmAas A nouvaau da fa^on A obtanir la maillaura imaga possibla. 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Un dee symbdee suivants appareltra sur la damlAre imege do cheque microfiche, seion la cae: la symbola -^- «lgnifie "A SUiVRE". le symbols y signifle "PIN". platae. charts, etc.. may be fHmad at different reduction ratioa. Thoea too large to be entirely included >n one expoeura ara filmed beginning in the upper left hand comer, left to right and top to bottom, aa many framae aa required. The following diagrame iiiuatrata tha method: Lee cartaa. planchee. tablaeu.x. etc.. iteuvent *tre fllmto i dee taux da rMuction diffiriMits. Lorsque le document eet trop grand pour itro roproduit en un soul clich4. II eet film4 k partir da Tangle supMeur gauche, do gauche i droite. et da haut en baa. en prenant le nombre d'Imagae n4ceeeaire. Lee diagrammee suivants llluatrent le m4thode. 1 2 3 1 2 3 4 5 6 V, "" >'JaMIIMI*MMIM '*mm^m FAUNAS OP THE PARAD0XIDE8 BEDS IN EASTERN NORTH AMERICA, NO. 1. '3y G. F. Matthew. Contents. ; PAOK. Introdnotion 102 Minate Cnistaceans 194 Oenns Agnostvia and its species 207 Qenus Miorodisoos and its species 236 The following article is a contribution to a revision of the faunas of the Paradoxides beds as they are developed in eastern North America. The region where these beds are found is spread along the Atlantic sea-board from New Found- land to eastern Massachusetts, and it is not known that the genus Paradoxides existed west of the Braintree basin in that State. In this article only the smaller crustaceans, including two genera of trilobites, are treated off. But these small fossi!) are as valuable for the correlation of horizons as the larger species, for they were as sensitive to a change of conditions as those, and tell the story of the sub zone which they mark with as great certainty as Paradoxides itself. In fact, they are even of higher value for this purpose, as a small piece of shale will contain a fully characterized example. In the author's former paper * an outline was given of the Cambrian system in eastern North America and its fbunas, so that it seems unnecessary here to do more than call attention to the sub-divisions of the Paradoxides sub-faunas as they are developed in this region. We know of the occurrence here of *TheProtolenus Fauna. New York Acad. Bel., Vol. XIV., p. 101. 193 TRANSACTIONS OF THE [may 18, t( four of the six sub-faunas into which the Paradoxides fauna is divided viz: Swyn(rU^ The Sub-zone of P. lamellatus Hartt (cf. P. Oelandicus). | «,* , " " " P. EteminicuB (cf. P. rugulosua). ^ ^ ' ' " P. Abenacua (cf. P. Teattini). " • " P. Davidia. . - - - « .f I ^-^ ' The first of these sub-zones is the oldest Paradoxides fauna of which we have any knowledge, and so far has been recongnized in two countries only, viz.. Sweden in Europe, and New Bruns- wick in eastern Canada. It is characterized by Hartt's species, P. lamellatua, easily recognized by the interrupted, raised plates on the front of the glabella ; the varieties of Conocoryphe and Ctenocephalus which occur here have more hispid tests than those of the next sub-zone. This sub-zone is the home of Mi- crodiacua Dawaoni and Lioatracua tener,* and occurs in Sweden. The next sub-zone, that of P. Eteminioua, has a wide range on both sides of the Atlantic, but seems to be most fully represented in the southern regions of the area over which the genus Para- doxides was spread. It is the most prolific band of the Para- doxides beds in New Brunswick, and is the only sub-zone recog- nized in Madsachusetts, France and Spain ; the species cited by Walcott indicate its presenoe in Newfoundland ; it occurs in Wales as the Solva group (or in that group); it is present in Bohemia, and is sparingly represented in Sweden in tlie " Ex- s'llens Kaik." The third sub-zone, that of P. Abenacua (a species closely allied to P. Teaaini of Sweden and P. Bohemicua of Bohemia), is represented in New Brunswick by a well-marked fauna, in which Ptychoparise and Solenopleurse abound. Microdiacus pulohellua is a characteristic species of this sub-zone, and it is a stronghold of the genus Agnostus. This sub-zone is doubtfully present in Newfoundland,f but it is in full force in Norway, Sweden and Bohemia. The highest sub-zone so far recognized in America is that of P. Davidia, which has a full representation at several localities in Newfoundland. It is characterized by the genus Anopolinus, by the species Microdiacua punctatua and by large Agnosti, in- oiuding examples of the Section Lsevigati. This sub-zone is f ^^J *W>looU oatalogueB this spectei ftrom Newfoundland as ooourring in hii zone A at Manuel Brook, but the ipeoiei quoted by him at aiioolated with it there, are of the next lub-ione. fl have ipoken of this horlson being preient there (Tram. Roy. Soo. Can., Vol. IV., p. IM) at Ch&pel Arm, but the preience of Anopolinui seemi rather to Indicate the next lub-ione. In Mr. Waloott'i Zone B. of the Manual Brook Section there is a mix- ture of the ipeoiei of the teriond and fourth lub-cone, but the preience of ipeciei of the intermediate cone doee not dlitiucily appear. TRAinACTiONi N. Y. Acad. Set., Vol. XV., Slg. 18, Auguit 4, 1896. |PW!W"iW"i«!rwiB«"«*»WB?»wwwnr«'« 1896.] NEW TORE ACADBMT OF SCIENCES. 194 t >»j well marked in Wales, where the species P. Davidis was discov- ered, and it is fully represented in Sweden. The other two sub-zones of the Paradoxides beds are not known to be represented in America, and so far as the author knows, have not been recognized outside of Scandinavia. That of P. For- chammeri is contained in the Andrarum limestone, a very rich repository of Cambrian forms, where the Paradoxides fauna may be said to h^ve culmihated. The higher of these two sub- zones contains only the dying remnants of this fauna and is known as the Zone of Agnoatua laevigatua. Rare remains of a Paradoxides related to P. Teasini have been found in it. I. D. Wallerius has lately described a number of new genera, speciest and varieties ftom this sub-zone in Sweden. The following is in brief the range of the American subfau- nas of Paradoxides so far as known : Sub-zone of P. lamellatus — New Brunswick only. Sub-zone of P. Eteminicus — New Brunswick, Newfoundland and Massachusetts. Sub-zone of P. Abenacus — New Brunswick and Newfound- land (doubtfully in the latter province). Sub-zone of P. Davidis — Newfoundland only. >• Descriptions of genera and species. Phyllopoda ? As compared with the Phyllopod crustacean of the Olenus and higher zones the fossils described below are very small. Their minuteness is an obstacle to the study of their characters, for there has been sufficient molecular movement in the shales in which they are imbedded to obscure the surface markings of such delicate fossils as these. They are supposed to be crusta- cean on account of the long, straight hinge line and weak um- bones and their defined bordering rim. • Lepiditta.* Obliquely semi-circular or semi-elliptical bivalves, wide on the anterior half of the valve and having a long, straight hinge line ; umbones in fVont of the mid-length of the hinge, low or but moderately elevated. Lepiditta alata (Plate XT., figs, la and 16). Lepiditta a/a^a. Trans. Boy. Soc. Can., Vol. III., pt. iv., p. 61, pi. vi., figs. 16, 16a. * Trans. Roy. Soo. Can., Vol. III., pt, Iv., p. 61. .\ 195 TRANSACTIONS OF THE [may 18, Valves obliquely semi-elliptical, about one-tbird longer than wide; binge line straight, umbo less than one-third from the ftont of the valve. Tumid part of the valve occupying about one-third of its length and about one-half of its width ; valve flattened toward the anterior and posterior ends. A faint nar- row rim is traceable around the outer edge of the valves. The cast of the right valve has a triangular umbonal promi- nence, about one-third from the A'ont ; the prominence is lim- ited in front by a sharp and deep fhrrow, placed at right angles to the hinge line, and extending thence toward the base of the valve ; the umbonal elevation is somewhat hollow in the middle, where it bears a sharp, narrow ridge, which is directed toward the posterior margin, at an angle of 50° from the hinge line ; a faint Airrow connects this ridge with the point of the umbo. The outer surface of the valves of this species is marked by numerous concentric striae, and by two faint radiating furrows^ extending on each side of the tumid part of the valve to the basal margin. The sharp median ridge and connected furrow, seen in the cast of the right valve of this species, are similar to those on the dorsal valves of some Brachiopods, but the position of the umbo separates it from that class of molluscs. Length, 1 mm. Width, | n^m. Horizon and Locality. In the fine, gray shales of Div. 1. c, at Hanford Brook, St* Martin's. Infrequent. f Lepiditta curta (Plate XV., fig. 2). Lepiditta curta, Trans. Roy. Soc. Can., Vol. III., pt. iv., p. 61, pi. vi.,flg. 17. Obliquely semi-elliptical and about two-sevenths longer than wide ; hinge line nearly straight ; umbo depressed, less than one quarter from the front of the valve. Valves fiattened toward the base and posterior end, the anterior margin has a flattened^ depressed rim ; and the front of the rim in the two valves was apparently connected by a triangular piece not bounded by dis- tinct sutures. The interior of shell has roughened zones or undulations con- centric to the umbo. This organism is not unlike the crustaceans of the genus Eatheria, but its resemblance to the preceding species, in form and hinge characters, indicates a generic relation. Length, 1^ mm. Width, 1;^ mm. Horizon and Locality. In the fine dark shales of Div. l.d^, at Porter's Brook, St. Martin's. Rare. 4fc jiiiwr^ifj'iirTii'iTr n immmw 1896.] NEW YORK ACADEMY OF SCIENCES. 196 Lepiditta auriculata (Plate XV., figs. 3a and 36). Lepiditta auriculata, Trans. Roy. Sec. Can., vol. xi., pt. iv., p. 99, figs. 2 a and b. Only a mould of the left valve is known. This is purse-shaped and has a short ear at each end of the hinge line. There is no marginal rim. Two grooves in the mould at the hinge line show, that the hinge had two oblique plates towards the posterior end. The surface of the ttiould is highest a short distance below the hinge, whence it descends gradually to the posterior margin, where the valve is nearly flat. This mould also shows faint, parallel ridges, concentric to what is supposed to be the anterior end. Faint lines mark off three quadrate spaces, near the hinge, parallel to the long plate, and corresponding in position to the upper seal-like marks of L. sigillata of the Protolenus Zone (Div. 1 6. 3). Size. — Length, 4 mm. ; width, 3^ mm. ; height of one valve, about ^ mm. Horizon and Locality. — In the fine olive gray shale of Div. 1 o at Hanford Brook, S. Martin's. This species is something like that which Mr. C. D. Walcott refers to Nothozoe Vermontiana, but has a longer hinge line and is more triangular in form; it is also much flatter than that species. Its long hinge line and hinge plates s^ow it to be of the genus Lepiditta. Ostbacoda. After the abundance of individuals and tlie variety of form in the Ostracoda of the Protolenus Fauna, the few found in the Paradoxides bed is somewhat of a surprise. Perhaps the Agnosti so common in the flne shales of bands c and d usurped the place of the Ostracoda. Primitia, Jones. This genus is represented by more than one species in the rocks of the St. John group, and the author proposes to describe here a very tumid form, of which a few individuals have been found. ' Primitia Acadica (Plate XV., figs. 5a-c). Primitia Acadica, Trans. R03'. Soc. Can., vol. iii., pt. iv., p. pi. vi.. figs. 22. 22 a and b. Outline of the valves elliptical.oblong, with but very slight >\ 197 TRANSACTIONS OF THE [mat 18, projection at the extremities of the hinge line. The valves slope down in all directions to the margin, and the form is so symmetrical that it is difficult to ascertain which is the upper and which the lower side of the valve ; but the side on which an obscure marginal fold is found, is supposed to be the lower side. It is also difficult to say which is the anterior and which tlie posterior end of the valve ; one end has a low tubercle and a shallow pit, while the other end is plain ; this distinction may be used for the purpose of locating the chara^pters of the inner sur- face of the test, as seen on the mould of the valve. The center of the valve is marked by a distinct circular depression, apparently a perforation of the test : from this point a faint medium furrow extends toward the tuberculated end, where it fades out in the shallow pit existing at that end of the valve; this pit is larger than the circular depression at the center of the valve, but difflers from it in having no defined margin ; beside this larger pit, but nearer to the margin of the valve, is the tubercle above referred to; it is low, somewhat pinched up at the sides, and elongated in the direction of the larger axis of the valve. The slope of the sides of the valve near the margin is nearly vertical, and the marginal fold is very feeble and obscure. The surface of the valve is 'granulated, but the granulations are more distinct on the inner than the outer surface ; the inner surface is more brilliant than the outer. This Primitia resembles in form and size the Silurian P. tran- siens, Bar.; its apparently perforated disc recalls another Bohe- mian species, P. perforata, Bar.; in this species the perforation and tubercle are situated near the hinge line, but in ours near the axis. Length, 3^ mm.; width, 2 mm. Horizon and Locality. — In the conglomerate-limestone band, Div. l.c% at Porter's Brook, St. Martin's. In his article on the Olenellns Fauna, of Washington county, New York,* Mr. C. D. Walcott has described a peculiar En- tomostracan with a flexible test under the name of Leperditia (/.) dermatoidea with the remark, " It may be that this spt^uies should be referred to a new genus." This fossil resembles one which the author has had in his hands for some time, unde- scribed. The peculiar wrinkling of the test (under pressure ? ) separates these fossils from all other Cambrian Ostracoda. and they are here placed in a new genus. /• •Fauna of the " Upper Taconlc " ol Emmons, in Washington county, N. Y., by C. D. Walcott. Am. Joar. 8ci., vol. xxxiv., Sept., 1887. •npr^wwn"P»p* 1896.] NEW YORK ACADEMY OF SCIENCES. 198 ' V Aluta, n. gen.* Small bivalves similar in form to Aparchites (oval or ovate), but having a soft, flexible test, and a fine somewhat dii^tinct punctation of the surface. There is no marginal fold or a very narrow one. Aluta Flexilis, n. sp. (Plate XV., fig. 4.) Oval about one-half longer than wide, and having a very nar- row rim. At the anterior upper corner is a tubercle (ocular?) enclosed by a shallow furrow. Towards the back on the upper part of the valve (in the only example known) is a broad, shal- low, circular pit ; irregular undulations impress the surface of the valve elsewhere. Sculpture. — Minute, rather distinct punctures. Size. — Length, 3^ mm.; width, 2^ mm. Horizon and Locality. — A calcareous band in Div. 1. c'^ at Porters Brook, St. Martin's, N. B. Scarce. ' This species in the position of the ocular (?) tubercle resem- bles Primitia oculata of the Protolenus Fauna, but the ^orm of the shield is different. The species ;« also near '/alcott's Leperditia rfermc'^trfes, which, although figured as ovate (if one may judge by tue description), include oval forms as well • thii t ♦he author makes no referciice to an ocular tubercle, so we find it necessary to made a specific description. The flexible wrinkled tesLcause/this fossil to be overlooked as the embryo of some trilooite, but there is no trace of an axial ridge. CiRRIPEDIA. V» «. While skeletons of creatures referred to this group of crus- taceans have been found in considerable numbers in the Ceno- zoic and Mesozoic rocks they are in lessened numbers in the earlier deposits ; and they are more difficult to recognize on ac- count of their wide departure in the detai^^of structure from existing types. Nevertheless we now find Cirripedes recognized as members of all the great faunas from the Ordovician onward, but the writer is not aware that any remains referable to these creatures have been reported from faunas antecedent to the Ordovician ; he, however, believes that such remains are present in the Cambrian rocks and proposes to describe herein such as appear to have belonged to Cirripedes. None of these occur contiguous to each other as to suggest the remains of one individual such as enabled Dr. Henry Wood- * Aluta^leather. ■ttb^iirfiliu^^a^HR^ - 199 TRANSACTIONS OF THE [may 18, ward to describe Turrilepas, or J. M. Clarke. Strobilepis, or C. L. Faber. Lepidocoleus, or J. Bairande.Plumulites, but when r^iinilar objects are found in the Cambrian system no doubt tliese genera will throw light upon them. The remains found in the Cambrian rocks of eastern North America are only scattered plates of the exoskeleton, and they are described largely with the object of inviting attention to the plates of this kind, not at all rare in some layers of the fine shales of the Lower Cambrian, which appear to be referable to Cirripedes. Of the genera mentioned above Plumulites appear to be recognizable in certain plates found in the Paradoxides beds of Newfoundland. Plumulites Barrande. In 1846 Barrande observed in the Ordovician rocks of Bohemia some peculiar plates of sub-triangular form and strongl}' ribbed transversely, which he called Plumulites. Eleven j-ears later he found plates of this kind grouped together in such a way as to show the kind of animal to which the}' had belonged. In 1864 Prof. Reuss, in connection with a memoir on the Lepadidre of the Oligocene of Germanj' and chalk of Qallicia, took occasion to point out that the Plumulites of Barrande were remains of Cirripedes.* In 1865 Dr. Woodward referred the valves from the Silurian beds of Dudley, Eng.. which de Koninck had called Chiton Wrightianiis to the Cirripedes lunder the name of Turrilepas. Thun b}' degrees the proper zoological position of these peculiar valves or plates, usually found loose and scattered in the shales of the Paleozoic rocks, came to be recognized. Barrande's description of Plumulites is somewhat dift'use, and has been summarized by Zlttel as follows :f Body elongated, resembling a pine cone, clothed with 4-6 (or more) longitudinal series of scaly plates. The plates are covered by strong trans- verse striae, somewhat in relief, and have a triangular form ; the median series are ordinarily distinguished from the lateral by their more convex form, and by the presence of a median keel. Barrande also found a peculiar, more oval valve in which the striju encircled the upper end, which valve he called valve fenl'$- trL Plumulites has been found in the Ordovician (where it was first recognized) of Bohemia and Ohio, and similar plates in the Silurian of England and the Devonian of New York ; it has not hitherto been reported from the Cambrian. The presence of so highly differentiated a class of Crustaceans •Syst. Sllur. UohOrae vol. 1., Sujip. p, .Viii. t Tratti^ du Puluuntoluglu. Zlttel iiud Uurrols. vol. it., p. :m. XMliP itmm^^immKmmmmmmw' ■ tm » u in 1896.] NEW YORK ACADEMY OF SCIENCES. 200 1 almost at the beginning of Cambrian time is a proof, if any were wanted, of the very earl^' origin of the Crustacean stem; and the rarity of plates that are found in the Paradoxides beds are sufficient to show that we are as yet but very imperfectly ac- quainted with these ancient tj'pes of Cirripedes. Barrande found the triangular valves of Plumulites three- lobed, by zones diverging from the apex, each having its peculiar sculpture. In describing these valves we propose to follow his nomenclature, the two slopes being designated respectively the convex and concave sides, and the third side (by which the valve was attached) the base. Plumulites Manuelensis, n. sp. (Plate X|V. fig. 7.) A triangular plate with curved sides, one concave, the others convex, rather blunt at the apex, somewhat straight along the base. A band difl'erent in elevation from the rest of the surface of the plate traverses it from apex to base and is nearest the concave side. There are about fourteen strongly marked trans- verse ridges traversing the plate, parallel to the base. Sculpture. — Fine striae (about four to a ridge) on the trans- verse ridges. Size. — Length, 4 mm. ; width, 3^ mm. Horizon and Locality. — Soft gray shales of Div. 1 d^, at Manual Brook, Conception Bay, Newfoundland. Scarce. This resembles in shape Barrande's P. compan of the Ordovi- cian of Bohemia, but is straighter along the base and more strongly arcuate in outline above the base. It is with great hesitation we refer the following genus to the Cirripedes as possibly representing the terminal plate of some such form as Strobilepis, or anchylosed plates similar to the terminal pair in Lcpidocoleiis ; but it seems as likely a relation as any other that has been suggested. Stenotheca Salter. This genns was proposed by Mr. J. W. Salter (published by Dr. Henry Hicks, in 18T2), to include a minute corrugated shell, found in the Menevian group in Wales. It vas described as n *' curved shell, a small wide form, with lines ot j^vowth strongly marked on its surface." The only species figured is S. cornn- i'opin. The genus is represented in the St. John (Jroup at one locality by numerous examples from the horizon Id? in a fine, dark shale. The little foiies of tills genua are always flattened, inequilateral, and usually have u more oi' less rigid band aloug ■Si 3S 201 TRANSACTIONS OF THE [may 18, the back. Though shorter and wider these objects are not unlike plates of Plumulites, not only do they have the same sharp, transverse ridges, but a similar arched band extends across the middle, from the apex. This genus when described was placed by its author among the Pteropods, but if I am right in having referred to it certain small fossils of the Para- doxides beds, there would seem to be features indicating affinities with the Crustaceans, and especially' with the ancient Cirripedes, rather than the Pteropods. J Stenotheca had thin calcareo-chitinous shells similar to the CUA.y^^ tests of trilobites;|( sharply raised ridges parallel to the lower border ; the apicai angle was bounded by two sides, one of which was convex and the other concave. The convex side is called dorsal, and the concave ventral, the third side is the aperture or base. Stenotheca concentrica. (Plate XIV., fig. 1.) Stetiotheca concentrica, Trans. "Roy. Soc, Vol. III., pt. iv., p. 59, pi. vi., flg. 11. Amended description. Outline of the compressed fossil rudely lenticular, the dorsal and ventral slopes being together equal to the strongly arched apertural margin. The apex varies from a bluntly rounded form to one which is prolonged into a short triangular point. For about one-third from the apex the sur- face has irregular undulations, about seven in number, concen- tric to the apex, and the rest of the test on the ventral slope about eight strongly marked ridges, concentric to the apex ; these ridges are increased on the dorsal slope to the number of twelve or thirteen by the intercalation of additional ridges in the dorsal third. Sculpture. The surface appears to have minute pores and is ornamented with linear ridgclets which have a roughly parallel and sometimes anastomosing arrangement. The most typical form of ornamentation is a chevron or zigzag arrangement of minute ridges, visible only with a lens, and most marked on the outer part of the shell ; these chevron lines sometimes cross two of the concentric ridges before turning and usually run angling across tlie ridges. The chevron sculpture varies to an irregular wavy arrangement of ridgelets, and ihat to a more or less linear grouping, which is the usual appearance of the ornamentation at the apex : occasionally straight lines on the primary ridges, alternate with wavy or somewhat zigzag lines in the hollows between. Another occasional variety of the sculpture is that of irregular wavy ridgelets crowned by little tubercles along the summit of the ridgelets; this gives the ettt'ct of a cancellated surface. i', phhm mtmmrnmffimmmmmrww^ 1896.] SEW YORK ACADEMY OP SCIENCES. 202 Size. — Height of tlie summit of the dorsal curve above the aperture, 3 mm. Length of chord of dorsal curve, 3^ mm. Length of aperture, 4^ mm. Horizon and Locality. — In the fine, dark gray shales of Div. 1 d.*, at Porter's Brook, St. Martin's. Not infrequent. This species may be compared with S. Cornucopia Salt, of the Menevian Qroup, in Wales ; it differs in having a wider aper- ture and more strongly arched dorsal slope. Six years ago a close examination of the surface characters led the author to refer this object (and its genus) to the Crus- tacea, chiefly from its punctate surface and from the fact that the sculpture showed more distinctly on the inner surface than the outer. The shell substance was also found to be calcareo- corneous, like that of the trilobites and other Crustaceans. Var. Radiata. (Plate XIV., fig. 2.) Stenotheca radiata. Trans. Roy. Soc. Can., vol. iii., pt. iv., p. 57, pi. vi., fig. 12. Outline lenticular, more strongly arched on the apertural than the dorso-ventral side ; dorsal slope about three times as long as the ventral ; apex larger and more prominent than in the type ; ventral slope more concave ; a sulcus about one-third from the dorsum, arching from the apex to the base, usually delimits the dorsal zone from the rest of the plate. There are about five irregular, concentric ridges on the apical part and ten more dis- tinct and regular ones on the rest of the plate. Sculpture. — Differs from that of the type in the general ab- sence of the chevron pattern (though in a band extending along the middle and at the outer margin this pattern sometimes ap- pears), but generally the arrangement of the ridgelets is irreg- ularly linear. Size. — Usually somewhat smaller than the type. Horizon and Locality. — In the gray shales of Div. 1 c at St. John; rare; also in the dark gray shales of Div. 1 d^,a.t St. Martin's ; more common. The example of this variety from Div. 1 r is smaller than those from Div. 1 rf*, and has strire radiating from the apex. A comparison of these little plates with the triangular plates of Plumulites will show that they are much alike, the essential differences being the doubling of the plate in Stenotheca, its broader aperture and tlie insertion of additional ridges near the dorsum. The Cambrian fossils have the same sharpness and close opposition of the ridges, and in a less distinct degree the radial banding from the apex. Though we noted the points of iSB 203 TRANSACTIONS OF THE [may 18, resemblance in composition and sculpture between these plates and the tests of trilobites some years ago, we did not then suspect them to be parts of Barnacles, and it was only after find- ing the plates of another species (S. triangularis) in intimate relation to the detached plates hereafter described as Cirripo- dites that we were led to suspect that they might be parts of Barnacles, and possibly such a hollow caudal plate as Dr. Clarke figures for Strobilepis. If we admit this, however, we must also be prepared.to allow that while this caudal plate was of calcareo- chitinous composition the lateral plates of the same creature were thicker and calcareous. Another possible explanation of these little plates is that they correspond to the dorsal row of small conical plates such as is seen on Strobilepis, but this seems less likely on account of their comparative thinness and flexibilit3'. Among the fossils of the St. John group which the author in previous papers has assigned to Stenotheca there are two types, that just described and another chiefly characteristic of a lower horizon. It is true that all these minute fossils have certain characters in common, as the compressed conical form, the strong ribbing of the surface and the thickened dorsal band. But they have also points of difference, for in the forms de- scribed below the ribs (exceptiin one) do not increase in number on the dorsal side ; they are more distant from each other, and there are pores or perforations at their extremities; these pores or holes form a row along the dorsal ridge and sometimes also along the ventral. The acquisition of better examples of Stenotheca triangu- laris than were in hand when this form was described, has led the writer to conclude that there are important differences be- tween it (and some others described with it) and the typical Stenothecre, enough to constitute specific, if not generic differ- ences between them, if they were complete organisms ; but as they are possibly onlj' parts of organisms it is unnecessary to make an}' generic distinction until the general structure is known. In the first examples studied it was not observed that the sur- face visible was not the outer surface of the test, but the surface of the mould of the interior, and the " long cylindrical apex '^ described and figured is really an internal tube in the apex of the cone. Stenotheca triangularis. (Plate XIV., figs. 4a and 4b.) Stenotheca triangularis, Trans. Roy. Soc. Can., vol. iii., pt. iv., p. 58, pi. vi., figs. 6 and bn, Stenotheca triangularis^ Trans. Roy. Soc. Can., vol. viii., pt. iv., pp. 133,134. '' mmm 1896.] NEW YORK ACADEMY OF SCIENCES. 204 Amended Description. — Form conical with an oval base and bluntly pointv- a apex. Viewed laterally the cone has a dorsal edge moderately convex, and a ventral edge slightly concave ; the base is straight for two-thirds of its length and turned up at each end. The orifice of the cone is a flattened oval twice or three times as long as wide ; the side of the cone is encircled by about six undulations of growth which arch upward around each end, corresponding to the curving basal margin. The cone has in its apex a short, annulated tube, about as long as the space between two of the transverse ridges of the surface. The upper two-fifths of the cone is thickened, and between this part and the base the cone has four perforations along the dorsal slope^ and there are perforations (four?) also along the ventral slope. On the inner surface of the cone there are sharp, engirdling grooves corresponding to the rounded ridges on the outside, and opposite the dorsal and ventral perforations these grooves, where they meet from the opposite sides of the cone on its inside, are enlarged into a cup-shaped cavity. Sculpture. — The rounded ridges of the surface are each tra- versed lengthwise by about six strite, visible only with a lens. Size.— Height 4^ mm ; length of base 5 mm. Horizon and Locality. — Fine grey shales of Div. 1 c', at St. John and Hanford Broolc, St. Martin's. Infrequent. This fossil has a thicker and firmer test than the two preced- ing kinds. The perforations recall those seen on the appendages of crustaceans as for instance those of Phyllopods, figured by Barrande,* and it appears probable that they are the points of attachment of mobile spines. Clarke figures a row of such in Strobilcpis, but not as being connected with the terminal plate. Stenotheca nasuta. (Plate XIV., figs. 6a and 66.) Stenotheca nasuta, Trans. Roy. Soc. Can., vol. iii., pt. iv., p. 68, pi. vi., fig. 13. Amended description. — Conical, subtriangular in side view, with deeply concave ventral slope and convex dorsal slope. Orifice of the cone strongly arched. As preserved in the shale there is a smooth raised band both on the dorsal and ventral slope, that on the former being wider ; in the space between are about six rounded concentric ridges, parallel to the base. Sculpture. — The surface is smooth, or nearly so, except on the dorsal band, where a number of faint striie, concentric to the apex, are made visible by a lens. Size. — Height, about 2^ nim.; length of base, 8^ mm. *8yitome Silurien de Boheme, vol. i., supp., pi. 10, flg«. il, 8, 10, &o. 1^ 205 TRANSACTIONS OF THE [may 18, & A^i^^^-t/,^ . 1896.] NEW YORK ACADEMY OF SCIENCES. 206 Type A, Plate XIV., Figs, a and 6. Ova) plates, usually rather flat, having a strong ridge length- wise, and often a more obscure, obliquely transverse ridge. The form is not a true oval, and is usually more angulated on one side than the other. Size. — Length, 6 to 8 mm. ; width, 4 to 6 mm. Type B, Plate XIV., Figs, c and d. Semi-ellipsoid plates. These also are nearly flat and have a slight furrow along the straight side. From near the center at one side faint furrows radiate toward the rounded margin. Some of these plates have two long sides nearly parallel. Size. — Length, about 8 mm. ; width, about 4 mm. Type C, Plate XIV., Figs e to h. Roughly semi-circular plates, with or without a flange on the straight side. Between the flange and the body of the plate is a deep furrow; body of the plate elevated and having an umbo which overhangs the furrow and from which a low ridge extends toward the rounded, often emarginate or obtusely pointed oppo- site margin. Usually the plate is depressed on one side of the keel and elevated on the other, and there are sometimes obscure subsidiary ridges radiating from the main keel or ridge. The flange is usually wider at the sides, and reflected backward, or emarginated in the middle. These resemble the peripheral plates of Trocbocystites, Barrande. Size. — Length, parallel to the furrow, 5 to 8 mm.,; width, 3 to 6 mm. . Type D, Plate XIV., Fig. i. Ovate plates with pointed end. These have a distinct furrow along the axial line; they are convex all around, and have a short ridge inside near the apex. Size. — Length, 6 mm. ; width, 5 mm. Rare. Type E, Plate XIV., Fig. k. Triangular plate rather flat, having ridges diverging toTttird the rounded corners ; ridges increasing in width and more prominent toward the outer ends. This plate may belong to a Cystidian. Size. — Length and width, 5 mm. Rare. Type F, Plate XIV., Figs. I and m. Sub-triangular plates, rather flat, with curved margins, one concave and the other convex. An arched furrow, nearer one margin than the other, traverses them Cirripodites cambrenais. Type G, Plate XIV., Fig. n. Triangular plates of high relief, sometimes showing facets of contact on the sides next the pointed end. One side of the plate rounded. Size. — Length, 4 to 5 mm. ; width, 8 to 4 mm. 207 TRANSACTIONS OF THE [may 11, Sculpture. — All these forms of plates, except for the keels and furrows described, have a comparatively smooth surface, there being only obscure lines of growth, and these not usually seen except toward the edges of the plates, and to these edges the lines are parallel. Horizon and Locality. — Gray shales of Div. 1 c at St. John and Hanford Brook, St. Martin's. Somewhat rare. The reference of these plates to Cirripedes is largely a matter of conjecture. As oval and circular plates have been found to occur along the dorsum of several genera of fossil Cirripedes plates of the type L and D may have had such a position, those of tj'pe B are evidently lateral, though the elongated form is unusual. Plates at the type O are more plentiful than the others and have the appearance of overlapping lateral plates. I have seen plates from the crown and lateral edges of a Trochocystites that resemble these, with similar flange and furrow. Plates of the type F more nearly resemble the opercular armature of modern Cirripedes, and seem to be^he representatives in the old rocks of the conical plates of Plumulites,'*' and are perhaps scutal plates, while the type O is analagous to the laterals of such a genus as Scalpellum.f The longitudinal curved ridge of type i^is com- parable to those figured by Barrande. Hall and J. M. Clarke.;]: The broad sub-semicircular 6r subtrapezohedral form of many of these plates may seem unusual, but is not without a prece- dent in extinct genera, as Archseolepas and Loricula, which have rows of similar broad plates on the peduacle.§ In the shales which contain Plumulites Manuelensis at Man- uel Brook, Newfoundland, are casts of calcareous plates which are similar to the above, thus resembling the coronal plates of Trochocystites ; but they are different in form from those of the Eteminicus z^*") at St. John ; the commonest form has a very heavy keel or furrow and is truncated at each end. The mate- rial is insufficient to determine the nature of these plates, which are sparsely scattered over layers in which Microdiscua punc' tatua abounds. TRILOBITA. AoNOSTUs, Brongniart. This is the most aberrant of all the primordeal trilobites of common occurrence, and the most difilcult to associate with the *SyBt. Stlur. Bohem., vol. i., Supp. pi. 20, flgs. 7, 8 and 9 b. Pal. N. York, vol. vli., pi. xxxvl., flgB. 1 and a. fTralt^ de Paleeontologie, Zittel & BarroiB, tome ii., p. 536. tSyst. Sllur. Bohem. vol. i., Supp. pi, 20, flgg. 22, 1 a and 6 h; also Pal. N. Y., vol. vil,, pi. xxxvi., flgs. 10, 11 and 16. ijTi niid de Paleeontologie, Zittel and Barrois, p. 538 and 634, ■PV^P«n (I II immmm iMV 'f^Km, 1896.] KEW YORK ACADEMY OF SCIENCES. 208 others by features held in common. The abortion of the pos- terior lobe of the glabella, the absence of the occipital ring, the immutable number of two joints in the thorax, all show the divergence from the common type ; and also there is seldom seen on an Agnostus the proof of that development and ex- pansion of the pygldlum which can be traced in the moulding of the surface of this shield in most other primordeal trilobites. Nevertheless there are some indications of a closer resem- blance between Agnostus and its allies in the earlier stages of growth than appear in the adult trilobite. Owing to the min- uteness of the shield in the j'oung of this genera, it is difficult to make out the outline and contour of the test in the early stages ; but it may be said that the pygidium is proportionately broader and both the marginal fold and furrow wider than is found to be the case at a later period ; in the early larval stages it thus approximates more in form and contour to other trilobites than at a later period. By comparing different species of Agnostus, and by a close examination of the surface features of the tests, we arrive at a few indications of the process by which this peculiar self-con- tained genus has been developed. To look at some Agnosti (e. g. Regii*) one would hardly suspect thatthere are more than two lobes in the glabella, but on examining others (Fallaces and Longifrontes) it will be seen that there has been an abortion of the true posterior lobe (called " basal lobes"), so that in the Regii it has become a mere ridge. The so-called posterior lobe of the glabella is also itself in some species seen to be indented by two pairs of furrows ; hence there are normally five lobes in the glabella. The abortion of the true posterior lobes of the glabella (the '• basal lobes ") is the fixation of an early larval condition in Agnostus. This lobe in Agnostus never becomes an integral part of the glabella, but consists of two small triangular lobes (sometimes nearly' obsolete) below the level of the glabella and connected behind it by a narrow thread-like ridge. The trian- gular form of these lobes is not erabr3'onic, it shows a larval development up to a certain point ; but its sub-ordination to the glabella and its separation from it, is evidence of subse- quent arrest of growth. The suppression of the occipital ring reduces the cephalic somites in Agnostus to five, which is the complete number in many trilobites which have this ring. In most species of Agnostus the occipital ring is not recognizable, hence the first *The several Rectioas Into whtoh the Kenua Agnostas has been divided by Tnllberg are described at page4iMr * -^ 209 TRANSACTIONS OF THE [MAY 18? joint of the rachis has no protecting cover, except in so far as the attenuated posterior lobe (basal lobes) of the glabella may assume that office, an unusual condition with trilobites. A. regulus is the only species known to me that has an occipital ring. Agnostus is the sole genus among the early Cambrian trilo- bites, except Microdiscus, in which the pleural groove runs for- ward in going outward toward tlie extremity of the pleura, and in association with this we find the point of the pleura in most Agnosti turned forward,* this is especially plain in Longi- frontes. In Fallaces the pleural groove on the posterior seg- ment lies along the front of the pleura, but on the anterior segment at the back ; hence the pleura in this group is inflated in the middle and tubercle-like ; on the anterior segment there are really two grooves, of which the anterior affords an inter- locking edge with the marginal fold of the head shield when the body if folded together. The long pygidium of an Agnostus assures us that this part has undergone very considerable changes from the early larval moults, but the proof is not often apparent ; an examination of the tests of two species (A. Acadicus var. declivis and A. Nathorst%) give an inkling of the way in which the changes have £ome about — those which resulted in the three-lobed rachis of the early Agnosti. In A. Nathorsti and other Lonlgi frontes the attenuated and de- pressed end of the rachis is the original pygidium, the front of this part is marked by a minute tubercle (to be found only in well preserved tests) ; in a rare example of the p3'gidium of de- clivis three pairs of scars behind this tubercle point out the existence of three somites here ; two pairs of scars in front of this little tubercle indicate the presence of two more somites, which complete the posterior lobe of the rachis ; these two som- ites swell out to greuvcr width and height than those behind ; the anterior of these two somites is also sometimes further marked off by a pair of furrows, one on each side of the rachis corresponding to the oblique furrow on each side of the anterior lobe of the adult rachis ; in Regii these furrows are so strongly developed that this somite was counted by Barrande as a part of the middle lobe of the rachis. The middle lobe and the anterior lobe of the rachis form another enlarged pair of somites with a tubercle or spine at the back, and correspond to the two front somites of the posterior lobe. We thus see that by its pygidium Agnostus shows three stages *An exception to this almost universal rule Is A. granulattu Barr., but it is one ut the few Ag:nosti ttiat tiave genal spines. NoTK-204 of last line p. 20H. slionld be 210. Transactions N. Y, Acad. 8ti., XV., Sig. II, August 14, WOO. y i "¥9 1896.] NEW YORK ACADEMY OF SCIENCES. 210 of development : 1. The early larval stage — non-agnostiform — when it possessed about 1-3 somites ; 2. The later larval stage — agnostiform — when it had about 4-5 somites ; 3. The adult condition, when it had about 6-7 somites, and the three main lobes of the rachis were developed with 4-5 somites in the pos* terior of the three. The above remarks are based wholly upon the three types of Agnosti that appeared in Europe and America simultaneously in the first sub-fauna of Paradoxides. To us the special features of the other two sections of the genus are of less moment, as they appear to be simply a progressive effacement of those that are found in the earlier types ; and it is in accordance with this that they appeared later in time, the Parvifrontes in the third sub-faunaof Paradoxides, the Lsevigati scarcely before the fourth, while these latter culminated in the sixth, seeing that the beds are called the zone of Agnostus Isevigatus. In these later types of the Paradoxides beds both the glabella and the rachis are effaced, so that scarcely any means remain of distinguishing the heads from the tails in these smooth tests. Nevertheless it is not such aberrant types that carry on the genus Agnostus to a later time, but modifications, more direct, of the primitive types ; for though the Regii disappeared from the stage of life in the early Cambrian time, Fallaces and Longi- frontes survived in the Ordovician seas, and the former lived on to its close. Thus this tj'pe which was the most abundant when the Agnosti appeared in the seas of Sweden, Wales and eastern Canada was the last to disappear when the genus was finally ex- tinguished at the close of Ordovician time. Tullberg, in his classical memoir on the genus Agnostus',* divides it into four groups, distinguished by well marked and easily recognized characters.f The arrangement is such as to greatly aid in determining the species of this large genus, so cbaracterisfic of all parts of the Cambrian from the Olenellus zone upward. The greatest development of the genus is in the Paradoxides zone, and especially the upper part. The following are TuUberg's sections : Longifrontes. " Distinguished by a manifest extension of the glabella and rachis, which commonly is rather long. Test some- times smooth, sometimes the cheeks are furrowed, sometimes the test both on the cheeks and pygidium is studded with elevated points. The marginal fold is generally narrow. The cheeks in *Otn AKnoBtUB arterna 1 de Cambrlska aflagrlngarne vid Andrarutn. S. A. Tullberg, Stockholm, 1880, fit may also with propriety be divided into Ave sections as the Limbati contains two very distinct types. 211 TRANSACTIONS OF THE [may 18, front of the glabella and the side-lobes behind the rachis of the pygidium are divided by an indented line."* This group, both in Sweden and eastern Canada, was one of the first to appear, and it proved also to be one of the most persist- ent. The following species and varieties may be referred to it : Agnostus obtusilobus. A A A A A A A Davidis, Hicks, gibbus, Linrs. var. partitus. var. acutilobus. - Nathorsti, Brogg. and var. confluens, n. var. - flssus, Lundg., and var. triflssus, n. var. ■ - punctuosus, Ang. Limbati. TuUberg divides this group into two sections, viz., Regii, of which A. rex, Barr, is the type, and Fallaces, with P. fallax, Linrs., as the type. Both sections are old, being found in the earliest Paradoxides beds both in Europe and America. This group (Limbati) has the following characters: "A shield which is generally more quadrate in form than the Longifronles; the head shield has a broader marginal fold ; the basal lobes of the glabella are more prominent ; the cheeks in front of the gla- bella are not separated by a furrow, and they are smooth, and the pygidium commonly has a pair of spines at the back margin." " The section Begii is distinguished by its broad marginal fold, by the reduced cheeks and reduced side lobes of the pygidium ; also the glabella, especially at the front part, is broad, and the third joint of the rachis of the pygidium is shortened." The Regii have been found in America in the first and third sub-faunas of the Paradoxides zone. Only two species are known. Agnostus regulus, and A Rex, Barr., var. transectus n. var. The section Fallaces has the following characters : " The head shield is smaller, the marginal fold not so broad, the cheeks are larger, the basal lobes of the glabella rather large, and the third joint of the rachis of the pygidium is the largest." The following species are found in eastern Canada and Nt v- foundland : Agnostus fallax, Linrs., var. vir. A var. concinnus. A var. trilobatus n. var. A Acadicus, Hartt. A var. declivis. * The last character is not constant as regards the pygidium,— G. F. M. mmm 1896.] NEW YORK ACADRMT OF SCIENCES. 212 Parvi/rontes. " This group is distinguished by the incom- plete development of the glabella, which is not divided into lobes." In eastern America this group appears first with the Abenacus sub-fauna, and has the following species : Agnostus parvifrona. A • var. tessella. A var. truncatus. A umbo. Leevigati. " This group is distinguished by the more or less complete etfacement of the glabella and the rachis of the pygi- dium.* The test is always smooth and shining, sometimes with traces of furrows. The marginal fold has a tendency to disap- pear from the head shield, but becomes broad on the pygidium." The group has been found in the Paradoxides beds of America, chiefly in those of Newfoundland. It comes in freely with the Davidis sub-fauna. The following species occur : Agnostus lavigati ^, Dalm., var. terranovicus n. var. A var. i :ceroides n. var. A var. mammilla n. var. ?A nudus Beyr. In describing the following species the author has not followed Tullberg's arrangement entirely, because he has found Longi- frontes rare in the first sub-fauna, their great development was in the third, fourth and fifth sub-faunas. On the other hand, the Regii appear to have been verging towards extinction, as in America they disappear with the advent of the Abenacus ^third) sub-fauna. The arrangement adopted is Regii, Fallaces, Brevi- frontes, Longifrontes, Lievigati. The Agnosti of the American Paradoxides beds have a definite order of succession, corresponding nearly to that observed in those of Europe, viz. : In the P. lamellutus sub-zone are the following: Regii. A. regulus — Fallaces. A. fallax,and var. vir.,and var. trilobatus — Longifrontes. A. gibbus and var. partitus. In the P. Eteminicus sub-zone. — Fallaces. A. fallax and A. AcadicuB. In the P. Abenacus sub-zone. — Regii. A. rex var. transectus — Fallaces. A fallax var. concinnus. A. Acadicus var. de- clivis — Parvifrontes. A. parvifrons and var. tessella and var. truncatus and A. umbo — Longifrontes. A. obtusilobus. A. gibbus var. acutilobus, A. Nathorsti and var. confluens, A. flssus and var. 3-fissus. *ThiB last (the effacement of the racliia) is not a constant feature. 213 TRANSACTIONS OF THE [may 11, In the P. Davidis sub-zone. — Fallaces A. Acadicus var. de- clivus — Parmfrontes. A. parvifrons — Longi/rontes. A. Davidis, A. fissus, var. trifissus, A. punctuosus — Lsevigati. A. Isevigatus var terranovicus, var. ciceroides and var. mammilla, A. nudus? Agnostus requlus. (Plate XVI., figs, la, 6 and c.) Agnostus regulus. Trans. Roy. Soc. Can., vol. iii., pt. iv., p. 67, pi. vii., figs. 1 a-c. Amended Description. — Body elongate-elliptical, with straight sides and semi-circular ends. Cephalic shield elongate, semi-elliptical: posterior contour broken by the projecting glabella and narrow occipital ring. Width and length of the head shield nearl;, ^qual. Dorsal fur- row distinctly but not deeply impressed. Marginal furrow and fold are sharply defined, and the latter diminishes toward the posterior angles of the shield. Glabella large, consisting of two lobes ; the anterior semicir- cular, wider than the posterior lobe, elevated above the general contour of the surface, and in some examples undulate with broad furrows, spreading from the back of the lobe ; posterior lobe flati,ened-cylindrical, with a broad, faint transverse furrow, one-third from the front, interrupted at the summit of the gla- bella by a small tubercle, elongated on the line of the axis. Basal lobes obsolete, being merged in the posterior marginal fold. Occipital ring minute, narrowly lenticular, concealed be- low the projecting obtusely angular end of the glabella. The cheeks are narrowed in the middle, there being a crescent-shaped limb in front of the anterior lobe of tl»e glabella, and a broad rectangular limb on each side of the posterior lobe of the gla- bella. The thorax consists of two segments ; the anterior subarcuate and marked by five lobes that are bounded by furrows radiating backward ; the inner pair of lobes are larger than the outer. The posterior segment of the thorax is unknown. The pj'gidium is elliptical, with straight sides, and is trun- cated in front of the side lobes ; it is widest at the anterior angles. The rachis is large, high, obtusely clavatc, constricted in the middle, and divided into three lobes; the anterior lobe is narrow, especially in the middle; the middle lobe is short and sublenticular in form and bears an elongated ridge like tubercle on the apial line that projects backward across the anterior seg- ment of the third lobe; the third lobe is subpentngonni in form and has a pair of side furrows in the widest part. The lateral lobes of the pygidium are narrowed opposite the posterior part of the rachis and meet behind it. 1896.] NEW YORK ACADEMY OF SCIENCES. 214 Size. — Length, 6 mm. ; width, 2^ mm. Horizon and Locality. — Found in the fine gray shales of Div. 1 c* at St. John and at Porter's and Hanford Brook, St. Mar- in's, N. B., but nowhere plentiful. This little species is remarkable for the large size of the gla- bella and the rachis ; in these features and in the expanded an- terior end of the glabella it resembles A. rex, Barr. and A. regiiis, Sjogr., but there are no raised lobes on the cheeks similar to those species, and the proportions of the glabella, etc., differ. It is nearest the latter species. Agnostus rex, Barr. var. transectus n. var. pi., xvi., fig. 2. This form difl'ers from the type as described and tigureJ by Tullberg in having the first and second segment divided com- pleteij' ; for there is no continuous ridge on the rachis from the front to the middle of the shield, as in the type ; but the ridge arises toward the back of the middle lobe, and thence stretches nearly across the anterior segment of the posterior lobe. It also differs from the type in the proportionately longer rachis, and in the narrowness of the raised area which encloses the end of the rachis ; here the rachis almost touches the flat- tened band which runs around the shield within the margin. Size. — Length of pygidium, &l mm ; width, 6 mm. Horizon and locality. — Dark gray shales of Div. I cP, at Por- ter's Brook, St. Martin's. Rare. Agnostus fallax, Linrs. pi. xv., figs. 8ft and b. (fj^'^t^ Agnostus fallax Linrs. Om Vestergot. Cambr. och silur- aflngr., p. 81, tab. ii.. figs. 54, 55. Agnostus fallax, Brogger, Om/Paradoxid. skifr. vecl/Krekling, Nyt. Mag., "Cliristiania, 1878, i).' 64, tab. vi., fig. 1, 1 a. Aqnoslus fallax, Liinvs. Ony faun, i lagr. med Paradox. QiJIand. Geoiog. foreiiin, Stockholm, 1877, p. 371, pi. 15, fig. 7. Ae caudal shield, about 3 mm. Horizon and Locality. — Fine grey shales of Div. 1 c.^. St. John. Scarce. This pygidium is of considerable interest because it represents in the adult condition a larval phase of Agnostus. It is instruc- tive to compare it with the 1 mm. larval form of vl./a//aa7 (type) (pi. XV., flg. Sh) which shows a similarly, but more impeiUjttl} , segmented rachis. This pygidium is the only one of the Fallax section which is distinctly segmented ; it thus expresses a con- dition of that shield quite common in the Longifrontes, and partly for that reason was at first thought to li)e the caudal shield of A. parlitutt ; the general facies however, is that of a Fallax. i AoNosTUS AcADicus Hartt. pi. xv., figs. lOra and h. A(i)WKiii)^ Acadicus Ilartt. Acad. Geol. 2d ed. p. 665. flg. 229, U. S. Geol. Surv. Bull. 10 p. 22, pi. ii., figs. 2a, h and c. Trans. Roy. Soc. Can. vol. iii., p. 70, i)l. vii , figs. 5a and h. Head minute, transversely elliptical, or subcirctilar, breadth and length about equal, convex but very depressed, outlines in front and on the sides slightly straightened. A narrow, flat- tened and but very slightly elevated border goes round the front and lateral margins. This is so|)arated from the rest of the shield by a narrow, shallow, flat space, or groove, which on going posteriorly along the lateral margins loses gradually in width towards the posterior angles of the shield, which are rounded. Glabella a little less than two-thirds of the length of the shield, long elliptical, depressed convex, but more elevated than other parts of the shield, about twice as long «s broad, bounded anteriorly auvl laterally by a sharp but rather deep groove concentric! to the outer one above described. A well marked transverse furrow arching backward separates the an- terior third of the glabella as ii sul)circular lobe, Posterior part of the glabella rounded, but impressed on each side by a little lOMi 1896.] NEW YORK ACADEMY OP SCIENCE I. 218 lobe situated in tlie angle between the cheek lobe and the gla- bella. These little lobes [basal lobes] are about one-quarter of tliesizeof the anterior glabellar lobe ; cheeks of the same width throughout, and uniting in front of the glabella, being bounded by the two concentric grooves above mentioned. Posteriorly they are rounded ; in width they are rather greater than the gla- bella. They are convex, more elevated along their inner mar- gin, but sloping outward roundly and evenly. Glabella with its lobes project considerably beyond the posterior margin. Sur- face' smooth. " Pygidium of this species (?) of about the same outline as the cephalic shield. The posterior and lateral margins have a slight, raised border, separated from the lateral lobes by a shallow but well marked groove, running parallel to the margin. This groove widens at the point, where it bends to go forward .along the sides in such a way as to encroach on and tliin out the marginal fold, and just before reaching the anterior margin it narrows itself from the inner side, so as to cause the lateral lobes to widen somewhat anteriorly. Tj^ese are narrow, flat- tened, about half as wide as the middle lobe, narrowing to a point just behind the middle lobe, where they do not unite. The medial lobe is about (Ive-sixtlis of the length of the pygidium, shield-shaped, flattened, convex, more elevtited than the lateral lobe. Its anterior border is slightly concave in the middle. The lateral angles are rounded, and the lobe is contracted a little anteriorly. It is bounded by two deep and well marked furrows, which join one another in the middle of the marginal furrow, forming a pointed arch; median lobe projecting farther forward than the lateral ones. A little spine is situated on its mesial line ; about one-fourth of its length from its front, surfaco smooth." Mr. Walcott remarks : "After a careful study of all the speci- mens in the collection, flfteen in number (Ilartt's collection at Cornell University), I am unable to make out suflicient difl'er- ence between the form described as A. Acadiux and that given as .1. Himilia, to establish two species. There is a certain range of variation in the specimens, as pointed out by Mr. Ilartt, but that is so variable and owes its origin so largely to the con- ditions of preservation of the various specimens that it is not evident that the two species are typifled." After examining much larger collections of the Agnosti of Piv. 1 (• (the horizon of the St. John group from which Prof. Ilartt's collections came), than Walcott had under review. I am not altogether satisfled with the the above determination, though it appears to be the best solution as to the use of Ilartt's names. 219 TRANS ACTIONS OF THE [may 18, 111 ,1 '!r It appears strange that while A.fallax and its varieties are by far tiie most common Agnosti of that horizon, Hartt should de- scribe only spineless pygidia ; these I find comparatively rare at this horizon, though they become plentiful in Div. 1 d (whose fauna Hartt did not have;. And then the description of A. Himilis more nearly accords with that of A. fallax than does that of A. Acadicus. Size. — Length of each shield, 5 mm.; width, 5^ mm. Horizon and Locality. — Grey shales of Div. 1 c at St. John, Radcliff's stream, etc. Vai*. DECLivis. pi. XV., figs. 1 la to d. Agnostus Acadicus var. declivis, Trans. Roy. Soc, Can. vol. iii., p. 70, pi. viii., figs 6a and b. This form is closely allied to A. Acadicus, but presents the following ditterences : It has a narrower border fold and smaller basal lobes, the glabella has proportionately a longer anterior lobe, and the furrow dividing it from the posterior lobe is di- rectly transverse ; the posterior lobe is strongly elevated, al- most tumid behind, and bears a small round tubercle at the middle of its length ; in front of the tubercle the lobe slopes down rapidly to the cross-furrow. Differences of equal import are found to exist between the pygidia of the tw "> forms. In var. declivis the rachis is cylindro- conical, and there are three minute lobes on each margin near the anterior end ; in A. Acadicus the rachis is more triangular in form, and both the head and tail shields are found of a larger size than those of the variety. The marginal fold is not quite even, but is interrupted not quite half-way to the back of the shield by a small, inconspicuous, knob-like spine. A pair of fur- rows just in front of the tubercle on the glabella, and snother pair a little behind it, both directed slightlj' backward, slightly indent the sides of the glabella. The thorax, of two joints, has three lobes on the axis of each joint, the mid-lobe being wider, and the side lobes lower on the posterior than on the anterior joint ; the pleura have furrows di- rected forward ; that on the hinder joint is placed on the front and that on the interior joint on the back of the pleura. This variety has tiie head of a Fallax with the tail of a Brevi- frons (e. f/.. A. parcifrons Linrs.). Development of the young. — Head shield of ^ mm. long has no visible basal lobes, but otherwise does not differ much from the adult. In a head l^J mm. long these lobes become visi- ble, but are very narrow and are confiuent with the posterior •laritinal fold. 1896.] NEW YORK ACADEMY OF SCIENCES. 220 The pygidium is more remarkable. One of | mm. has an oval form ; the anterior margin is straight and without fold, mar- ginal fold around the rest of the shield widening backward. Rachis oblaneeolate, trilobed by faintly impressed furrows, front lobe narrow, middle lobe wide but not tuberculate, side lobes with two transverse furrows, the posterior about one-third from the front. In this individual I conjecture that the anterior of the two, furrows on the side lobes, will become the anterior marginal fur- row of the pygidium, and the posterior a first furrow on the side lobe; the p3'gidium would then agree with a similar stage of Microdiscus as regards these lobes, but not as regards the rachis. This minute pygidium shows a simpler structure than the adult, which, notwithstanding that the I'achis is not segmented, is sometimes so preserved as to show the number of somites in the rachis. Thus the adult caudal shield (see pi. xv., fig. l\d) is sometimes well enough preserved to show on the cast of the inner surface a row of minute tubercles on each side of the rachis (five in number) and two on the axial line; the lateral tubercles are placed on the line between the somites, and each of the axial tubercles in the middle of a somite ; it thus appears that the somites are in pairs, one with and the other without an axial tubercle. The first and second somites correspond to the first and second lobes of a Longifront pygidium, and the re- mainder of the axis to the third lobe in the pygidium of an in- dividual of that section of Agnostus. Also we observe that while in the first larval stage there are only three somites recog- nizable in the p3'gidium, the adult caudal shield has six. Agnostun declivis may be compared with the later A.secretus Wale, of the Prospect Mountain group, which it resembles in general form as well as in having the glabella tumid behind. Neither this variety nor the type of A. Acadicus appears to have any very near allies among the jpecies of the Paradoxides beds of Sweden, known to the r.iuhor. Size — Length, about 7 mm. Width, 3 mm. Cephalic shield 8x3 mm. Horizon and Locality. — Abundant in the fine, dark shales of Div. 1 d* at Porter's Brook, St. Martin's. AoNOSTUs PARViFRONS Llnnarsson. Aqnostus parvifrons Linrs. Om. Vestergotland Cambr. o. Silu'r. aflagr., p. 82, tafl. 2, fig. 5G. 57. A(fnoi>ti(x parmfrona Tullb. Om. Agnostus-arterna, p. 34, tnfi.'ii., figs. 2fi, 27,28. PTP" 221 TRANSACTIONS OP THE [may 18, 'mI'm Test smooth. Head-shield enclosed by a marginal fold that is broader in front. Glabella small, round, not lobed. Basal lobes small. Cheeks expanded, connected in front of the gla- bella ; pygidium without spines ; marginal fold wider behind ; rachis long, almost reaching the border ; lobes sometimes obso- lete, sometimes apparent; middle joint ornamented with an elevated point; lateral lobes narrowed behind, scarcely con- tiguous. « Size. — Length and breadth of each shield, 3^-4^ mm. Horizon and Locality. — Dark gray shales of Diy. Id^ at Porter's Brook, St. Martin's, etc. Mr. C. D. Walcott has described a species of Agnostus of the parvifrons type found in the Lower Cambrian rocks of Wash- ington County, N. Y. Being claimed as a Lower Cambrian (i. e., Olenellus Zone) fossil, it is not figured here. The glabella is longer than in A. parvifrons. It may be remarked, however, that this type of Agnostus is not found elsewhere lower down than the P. Abenacits (—tessini) sub-zone. A common variety in Canada is the following : Var TESSELLA. pi. xvi., figs..a to c. Agnostus tessella. Trans. Roy. Soc. Can. vol. iii., pt. iv., p. 71, pi. vii., figs, la to c. This is a transitional form to the Limbati (Fallaces). It dif- fers from the type in having an anterior lobe to the glabella faintly defined ; this has no furrow like the posterior lobe, but is marked out by a faint thread-like line on the surface of the test. The posterior lobe is intermediate in length between the two glabellas of A. parvifrons figured by Tullberg, but rect- angular in front. The pj'gidium is similar to tig. 276of Tull- berg's plate, but the tubercle is elongated, not round as in that form ; the rachis is wider, and its middle lobe proportionately shorter. The marginal fold does not have so great a width be- hind. Size. — Length and width of the shields each 3 mm. Horizon and Locality. — Same as the preceding. Development of the Young. — A head shield ^ mm. long is nar- row, marginal fold and furrow distinct. Glabella long, front fur- row distinct, two others faintly marked by depressions crossing the glabella; basal lobes very narrow, scarcely visil.c* A head 1^ mm. has -nearly the form of the adult, slight fur- rows at the anterior corners of the glabella as in A.fissus var. •This Is In npoordance with the ohnnKos of this lobe In the Ptychoparldoc In which during the first larval satges this souilte la very narrow and weak. 1396.] NEW YORK ACADEMY OF SCIBlNCES. 9'T>> trifiasus. A head 3^ ram. shows three fore-furrows of the gla- bella as A. trijisiius, but no axial furrow of the glabella. A pygidium ^ mm. long, is wide, subquadrate, marginal fur- row distinct, not widened ; fold widened, cuspidate, rachis promi- nent, front lobe divided off by a shallow furrow, second lobe de- fined only by the axial tubercle, third lobe not defined, weak, rapidly descending below the cheek lobes, which are wide be- hind the rachis. A pygidium 1^ mm. long, is quadrate; the third lobe from the front is defined, but the little tubercle is ab- sent. Another common variety is the following : Var. TRUNCATUS n. var. ? ? Agnostus tritncatus Brogg. Om. Paradoxides skifrene ved Krekiing, p. 72, tab. vi., fig. 8. Brogger's figure, except that it is somewhat more quadrate and larger, is not distinguishable from a common variety' of A. parvifrons that occurs in the St. John group. The variety found here does not differ from var. tessella, except that the front lobe of the glabella is entirel}' suppressed, and that the individuals are found of larger size. Size. — Length and width of each shield, 4 mm. Horizon and Locality. — As the preceding. Considering these varying forms, we are impressed with the justice of Tullberg's remark that this is a variable species. In Agnostus Acadicus of Hartt we may perhaps have an ancestral form of this species ; that occurs in the sub-zone of Paradoxides Eteminicus ; then in the sub-zone of P. Abenacus we find three other forms, var. declivis of J. Acadicus, in which the front lobe begins to be depressed, var. tessella of A. parvifrons, in which the front lobe is traced out on the surface of the head-shield only b}' an impressed line, and not by furrows, and var. truncatus, in which the front lobe entirely disappears ; finally, one may add the t3'pical form of A. paruifrons, in which any suggestion of an anterior lobe is removed by the rounding of the front of the glabella. It will be noted that there is a resemblance in the pygidia of all these forms, and that A. Acadicus differs from the typical Fallaces in the absence of marginal spines to the pygidium, a feature which it possesses in common with all pnrvifrontes, AoNOSTUs UMBO, pi. xvi., figs. 4a and h. Agnostus umbo. Trans. Roy. Soc. Can. vol. iii., pt. iv., p. 71, pi. vii., figs. 8rt and h. Body elliptical, broader in front than behind, high at the inner side of the head and tail shields, descending thence to the front 223 TRANSACTIONS OF TUB [may 18, :•!! .Ill; and back. Cephalic shield broadly-transversely elliptical, high and contracted behind, sloping from the glabella in all direc- tions. Marginal fold and furrow sti'ongly marked. Dorsal fur- row deep. Glabella suborbicular, rounded in front and behind, bearing a small tubercle on the axial line, one-third from the front ; the width of the glabella is more than a third of that of the shield, and its length nearly half. The thorax is unknown. The pygidiura is semi-elliptical, with rounded anterior corners ; the width is nearly a quarter greater than the length. Both dorsal and marginal furrows are deeply impressed. The rachis is conical and is greatlj"^ elevated above the rest of the shield ; it is slightly constricted near the anterior end, and about one-third • from the front bears a small tubercle. The lateral lobes of the pygidium are rounded in at the anterior end by the rapid curve of the marginal furrow ; and at the posterior end are gradually narrowed and are separated at that end by a furi'ow which con- nects the dorsal and marginal furrows. The marginal fold is rather wide at the extremity of the pygidium, and is rounded at the anterior corners. This species is distinguished from A. tessella by the entire ab- sence of the anterior lobe of the glabella, and by the round and prominent posterior lobe, having a small tubercle in advance of the middle of the lobe. The pygidiura has a shorter, higher and more conical rachis, and the tubercle on it is round, not elongated as in A. tessella. The head shield of A. parvifrons var. mammillata Brogg re- sembles that of this species, but is longer ; the rachis also of the pygidium is more cylindrical and its tubercle further back in Broggers' variety. Size. — Length, 6 mm.? width, 3 mm. Horizon and Locality. — In the fine dark shales of Div. 1 d^, Porter's Brook, St. Martin's. First collected by Dr. L. W. Bailey. The following species are classed as Longif routes, although, from the absence of axial furrows, the one which is here first described might seem to be not properly placed there ; but the thin, flexible test, the large basal lobes and the attenuated and segmented rachis seem to point to this as the proper place for Agnostus obtusilobus^ the largest species found in the St. John group. Agnostus obtusilobus, pi. xvi., fig. 5. Agnostus obtusilobus. Trans. Roy. Soc. Can., vol. iii., pt. iv., p. 72, pi. vii., fig. 9. Amended Description. — Body elliptical oblong. Cephalic MPMI "mm 1896.] NEW YORK ACADEMY OF SCIENCES. 224 shield semi-elliptical, about one-quarter wider than long. Dorsal furrow faintly impressed. Marginal fold and furrow strongly marked. Glabella elliptical-elongate, wider behind, rounded in front, in its widest part nearly a third of the width of the shield ; narrowed at the base by two triangular lobes ; a semi- elliptical lobe at the anterior end more than one-third of the length of the glabella. Occipital ring and posterior marginal fold narrow. Cheeks continuous in front of the glabella. Thorax of two segments ; the anterior segment has five lobes, of which the outer pair are globose and the inner pair subtriangular and widest in front ; the center lobe is semi-circular, broad behind, and bears an elongate traverse tubercle in the middle. The posterior segment has three lobes, of which each of the twO' lateral ones is globose, and l)ears minute tubercles ; the central lobe is subrectangular elongate, and the middle half is traversed by an arched furrow, which begins and terminates on the pos- terior margin of the segment. The pygidium is semi-elliptical, about one-sixth wider than long, and has the anterior margin arched forward. The marginal fold and furrow are about as distinct as those of the head shield. The rachis is oblanceolate. constricted in the middle, clavate, and pointed behind, about one-third longer than wide; it is traversed by two furrows, of which the one near the anterior end arches forward, and the other, near the middle of the rachis. arches backward. At the broadest part of the axial lobe there is transverse depression. The first segment of the rachis is narrow and elevated trans- versely ; the second segment is elevated lengthwise, having an elongated tubercle at the axial line that projects backward on the third segment \ the third segment is triangular and depressed across the middle, and bears a small axial tubercle on the an- terior third. Sculpture. — The surface of the test in this species has a vel- vety appearance, and under the lens is seen to be covered with minute granulations, the surface also is rugulose or uneven, and the test thin and more apt to be distorted than those of the two preceding species. The parts of the body in this and the follow- ing Longifrontes are more frequently found connected than are those of the preceding species ; and while in the species above described the two shields are often found doubled together, in this and the following species the}'^ are frequently spread at length. This species resembles A. scarabeoides of the Welsh Cambrian rocks, but has a narrower glabella with a more obtuse front. Length, 11 mm. Width, 6 mm. Horizon and Locality. — In the fine dark grey shales of Div. 1 rf^, at Porter's Brook, St. Martin's. Infrequent. w^ 225 \ TRANSACTIONS OF THE [may 18, The pygidium of this species may be distinguished from that of A. acutilobus in the fact tiiv. Irf'. Porter's Brook, St. Martin's N. B., Canada, scarce. Tullberg remarks in his work cited above, that the shield fig- ured by Angelin as the pygidium of Agnostus exsculptus is really the head shield of this species (A. Nnthorsti). 'KlKure* lii.1t, |il. V,, rvrorrvd t().■l.«<■l«^lf<«llrlMlot of thiN»|iv('le!i, InUrepruiontiiome »prok>»of tlu' Llmlmtt Hyctloii (ii FiiUiix). 1896.] NEW yO..K ACADEMY OF SCIENCES. 230 J Some examplea from the St. John group have the axis of the pygidiiim long and a furrow behind, connecting the dorsal and marginal furrow; these agree more nearly with the European form. The following form, however, is more plentiful. Var. coNFiiUENS n. var. Plate xvi., flg. 9, a and b. This form is found in the eastern part of the St. John Basin. It does not quite agree with Broegger's species, but differs in the following respects: The iiead sliicld is less quadrate behind, the furrows on the sides of tiie posterior lobe of the glabella less undidatc, the basal lobes longer. The pygidium is more quadrate, the pos- terior margin less arched, the [msterior lobe of the rachis is shorter and wider than in the type, and the side lobes are not separated behind the rachis by a furrow. Sculpture. — The surface of the test especially in the head shield is radiall^y wrinkled. 8ize. — Length and width of each shield, about 4 mm. Horizon and Locality. — Dark gray shales of Div. 1 d'.at Por- ter's Brook, St. John county, N. B. AciNOHTiiH FiHsus, Luudgrcn. ArpiOHtuH fiHHiifi, Linrs. Om fauna i Kalkcn mcd Conoc. ex- suleiiH, p. 23, tafl. ii., fig. 34. Affnontiiit JlifHUH, Tullb. Agnostus arterna vid. Andrarum, p. 16, tafl. i., fig. 3, a to d. " Head and pygidium shorter and wider [than A. gibbim']. Test scarcely smooth, uneven, marginal fold narrow. Glabella shorter, broader, bilobed. Anterior lobe no longer than wide, more or less l)lunt in front, cleft in front by a very delicate line, equal to the posterior lobe iu width ; posterior lobe short for its width, one d('|)r"Hsion visible on each side, reaching its greatest height a little ill front of the middle of this part, where an elevated point •..M] be seen. Basal lobes small, triangular, scarcely con- nectiisK b. Nearly the same size as the preceding. It has more distinct basal lobes, but the difference is chiefly in the pygidium ; the rachis Is undivided and greaty elevated at the second somite where there is a prominent tubercle one-third from the front of the rachis ; the lateral lobes are divided by a furrow, and the posterior marginal fold is wide. Sculpture. — As the preceding but with small scattered tuber- cles on the head shield. Size. — Length and breadth of the shields, nearly 4 mm. Rachis of the pygidium : length, 2i^+rara.; width, l^+mna. Horizon and Locality. — Found with the preceding. While the head of this variety is that of a Loevigatus, the pygi- dium is nearly that of a Parvifrons ; in the latter, however, the dorsal and marginal furrows of the pygidium are confluent, in this variety they are distinct, but connected by a cross-furrow. But for the absence of glabella this variety would closely re- semble Broegger's var. mamillaliis of A. parvifrons. 235 TRANSACTIONS OF THE [may 18, In Agnostus Barrandei, Salter, of the Menevian horizon in Wales we evidently have a species of the Lsevigati section, and although Dr. Hicks' figure* does not show any rim, the descrip- tion indicates that there was one ; from this and the pygidial features this species appears to be allied to A. leevigatus, rather than A. nudus ; but judging from these features, also the two individuals figured must at least be of diflTerent varieties ; Fig. 5, if we be guided by the form of the rachis, approaches var. forfax^ and Fig. 6 var. terranovicus ; the resemblance does not establish an identit3' in either case. ? AoNOSTUS NUDUS, Beyi'ich. This species appears to be indicated by some head shields found in Newfoundland. The head shield is high at the back in the middle and arched down in all directions, and is devoid of marginal fold. Sculpture. — Smooth and shining with a minutely punctate sur- face. Size. — Length and width, 3 mm. Horizon and Locality. — Limestone of Chapel Arm, Trinity Ba}', Newfoundland. M1CRODI8OU8, Emmons. This genus, which in the small number of the pleural joints, is almost on a par with Agnostus — for the number varies from two to four for the different species — is characterized bj' certain changes of form from its earliest appearance until it died out in the later stages of the Paradoxides beds— changes which are com- parable to those in Agnostus, but on difflerent lines: one of these lines of development is the obliteration of the costj« on the side lobes of the pygidium, and the other the extraordinary develop- ment of the occipital spine. The " great nuchal spine " as Salter calls it is not merely an extension of the summit of the occipital ring, but in some species at least it carries with it the posterior part of the glabella ; hence these species have no proper occipital furrow, but the two outer ends of this furrow are seen to run a little way up the side of the spine or form a threadlike band at the the back of the spine; in such cases the main furrow seen at the base of the spine is in reality the posterior glabellar furrow, and this lighter furrow behind is the occipital furrow. The obliteration of the occipital furrow in many species of this genus leaves one less than the normal number of furrows on the axis of tlie head shield, so that usuall}' not more than three, * Quart. Jour. Geol. Soc, Loudon, May '72, p. 170, pi. V., Figa. 5 and 0. ■ MM 1896.] NEW YORK ACADEMY OF SCIENCES. 236 sometimes only two, can be discerned. All the furrows are usually indistinct or even obliterated in the later species of the Pai'adoxides Beds, in the adult shields ; but even in these there are often impressions of these furrows on the inner surface of the test. It is in the species of the Olenellus Zone that the series of fur- rows marking the somites is most clearly seen. M. speciosiis for instance has three pairs of broadly, but distinctly impressed fur- rows on the sides of the glabella and also a pair of sharply cut occipital furrows,* In M. lobatus the furrows of the glabella are not quite so obvious, and the posterior of the three is usually very indistinct, but tiie number is the same as in the preceding species. Both Agnostus and Microdiscus exhibit larval oharr^ters in the anterior lobe of the glabella, the former by the large size of the anterior lobe (as in Uegii) or its distinctness (v.s in Fal- laces and Longifrontes). In Microdiscus, however, the larval facies is maintained by the large size of the anterior lobe as compared with those behind it. The Ptyclicaridje in the Pro- taspis stage, which the author has studied, agl^e in having the somites of the cephalic axis short except the front one which is much larger and longer than the others ; as regards the length, this is a permanent characteristic in the typical Microdisci of the Olenellus zone, for in these the front lobe is nearly as long as the other three.l As in Agnostus, and in manj' other trilobites the pygidium of Microdiscus is divided into an anterior and a posterior part, the latter distinguished by the imperfect segmentation of the rachis ; this is very well seen in the section (Eodiscus) described hereafter, wherein the protopygidium is marlied by a tubercle on the summit of each ring of the rachis, while on the neo-pygi- dium there is a row of low tubercles along tlie crest of the ring, similar to those on the lateral lobes (of M. puJchelhin, etc.). The pygidium in this group by the appearance and subsequent effaceraent during growth of costie on the side lobes shows the addition of somites beyond the number of those of the early stages ; while in otiier sections as Dawsonia (see below) the sur- face moulding shows the cementing of additional segments to the front of the pygidium. | A general rule holds in the genus Microdiscus as to the in- crease of the number of rings in the rachis of the pygidium, ac- cording to the geological age of the species ; the majority of those ♦On many heads of adult examples of M. apectosus all these furrows are quite ob- literiited. t ^f. .iiteotosiis iind ^r. Inhfilun, but this Is not the case with ^f. Schucherti In which this lobe 18 short iis In the Microdisci of the riiruiloxldes beds. JSee also the pysldluni ascribed to M, prveurmv. 237 TRANSACTIONS OF THE [may 18, of the Olenellus zone have but few rings (4 to 6), but in the Paradoxides zone, species with many rings (8 to 10 or evfen 12), are multiplied. The late Prof. C. F. Hartt recognized the dis- tinction between these two sections of the genus as it occurs in the Paradoxides beds, giving to one the name Dawsonia and to the other Eodiscus. The following scheme will show how the species of Microdisous are related to each other : Lateral lobes of Pygidial rachis has. ribbed sely 4 rings i c« 1 pygidium unknown ribbed smooth tal ring obtn pointed unknown 6 rings 6 rings smooth occip 12 rings smooth 10 rings Section lobatus lobatus, Hall, 1847* Meeki, Ford, 1876 I Parked, Wale, 1886 Helena, Wale, 1889 i Section sPEciosus I speciosus, Ford, 1874 bellicinctus, Shaler& F, 1888 • Horizon. Olenellus Zone. Olenellus Zone. I: S So If ;f « ! 6 to 7 \ ' 3 s rings j 6 rings • 3& Section Dawsonia t Dawsoni, Hartt, 1868 sculptus. Hicks, 1871 Paradoxides lamellatus Sub-zone. B .5 6 rings 3 >>| 6 rings ■|5 I unknown^ Section eodiscus % Schucherti, n. sp. connexus. Wale, 1887 precursor, Matt., 1885 suecicns, Linrs., 1892 pulchellus, Hartt, 1884 punctatus, Salter, 1864§ eucentrus, Linrs., 1882 Olenellus Zone. i^lenel. z.(?) Paradoxides eteminicua^f Sub-zone. ' P. Abenacus sub-zoue. Paradoxides. Davidis sub- zone. ♦ First published ns nn Agnostus. •f Used by Hartt for .V. Dawaimt, published by Unwson, ISflS. t Name used by Htirtt (probably about 1870), not published until 1881. (I The type of the geuus. 1896.] NEW YORK ACADEMY OF SCIENCES. 238 The embryonic tests of individuals of the section Eodiscus uo not show an}' characters special to the genus, but these speedily appear in very small larval tests, and are first recog- nizable in the headshield. In general outline and in having costal ribs on the sides of the pj'gidium, this part of a young Eodiscus is much like that of a Ptychoparia at the corre- sponding stage, but in the later moults the distinctive features of Microdiscus appear; the rings of the axis become more numerous, the pleural lobes inflated and the form of the pygidium more elongated. In the species of this section (Eodiscus) the furrow on the pleurae (of the posterior joint at least) run forward and outward as in Agnostus; this is per- haps due to the strong geniculation of the anterior marginal fold of the pygidium, necessitating a convexit}' of the overlap- ping pleura. The genus Microdiscus serves as a link between the Paradox- ides and the Olenellus faunas, and there is a gradation of re- sembling species through two lines of development, one with few, the other with numerous joints in the rachis of the pygid- ium. Though Microdiscus is so common in the Olenellus Fauna and passes into that of Paradoxides, no example has been found in the Protolenus Fauna. H. (i p. Plate xvii., figs. 4 a and h. Microdiscus Schucherti Headshield subcircular, one-quarter wider than long, flattened in front, drawn in and upturned at the gen.il angles ; axis pro- jecting behind. Anterior mai'ginal fold enclosing a flattened area, which is indented in front of the glabella. Glabella two- thirds of the length of the shield, cylindro-conlcal, depressed in front, elevated and projecting backward behind ; three pairs of furrows faintly impressed on the sides. Occipital ring not vis- ible. Cheeks moderately arched, not meetu'^ in front of the glabella. Posterior marginal fold wide .at the outer end, shield narrower here than opposite the cheeks. Thorax not known, but the relief of the approximate mai'gins of the two shields indicates a prominent rachis and strongly' geniculate pleurie, with furrows directed forward. Pygidium longer in proportion than the head shield, and more decidedly arched. Rachis nearly three-quarters of the length of the shield ; it has about six joints, the anterior four prominent and each crowned with a tubercle. Side lobes sloping down to a flattened marginal fr!a, which is strongly genlculated in front, with an almost vertical outer slope. Sculpture. — Surface of both shields minutel.y granulate. ^. ^^^W^i-, '-iCyt~. f /yv^ ^c^A-'C^ ) 239 TRANSACTIONS OF THE [may 18, Size. — Length of P3'gicliiim, 3 mm.; width, 4 ram.; the head- shield is somewhat shorter. Horizon and Localit3'. — Limestone of the Olenellus Zone at Troy, X. Y. Collected by Mr. C. Schuchert and communicated to the author. Though this species is not of the Paradoxides Zone, I have described and figured it here on account of its resemblance to the larval stages of certain Microdisci of that zone. It differs from others with which it occurs in its short glabella and broad, depressed head shield ; in these points it is like M. Daivsotii. While the typical species of the Olenellus Zone have retained the occipital ring, it appears to be wanting or nearly effaced in this species, as in several species of the Paradoxides Zone, and in the Agnosti. The larval pygidia of the Eodisci {M. jjulchellus, etc.) resemble the adult shield of this species in contour, num- ber of rings in the rachis, etc. And it is to a fixed larval stage of this tj'pe, rather than to M. pulchellus, M. punctatus or M. DawHoni that the author would look as the source of such a form as M. connexus, Wale; for this species differs little from M. Schucherti, except in the extension of the occii)ital spine. All our examples of M. Schucherti show only the outer surface, and so it is not known whether tiie border fold of the head shield is crenulated within. Mtchodtscus precursor. Plate xvii., fig. 7. Microdiscus punctatus var. preeuraor^ Trans. Roy. Soc. Can., vol. iii., pt. iv., p. 75, pi. vii., fig. 13. Only the head shield of this species is with certainty known. It resembles M. pulchellu)^, but is more triangular in outline. The marginal rim is very narrow ; the dorsal furrow is deep and wide and connected with the marginal furrow by a shallower furrow. Glabella shows two faint pairs of furrows at the sides, Microdiscus precursor, supposeii pygidium mag. V'- (This figure should have been placal between ligs. 46 and 8rf on Plate xvii. ) on the inside of the test, smooth on the outside. The occipital ring bears a tubercle or short spine. Tiie cheeks are tumid, nearly straight on the side next the dorsal furrow, to which they descend abruptly; at the posterior inner corner is a prominence which projects toward the glabella in front of the occipital ring. 1896.] NEW YORK ACADEMY OF SCIENCES. 240 Occurring at the horizon of this species there is a somewhat long semi-circular pygidium which may belong to this species ; a young example possesses the following characters. It is one and a-half times as wide as long. Ilachis narrow and prominent, about one-fifth of the width of the shield, and three-quarters of its length; two rings are divided off the front by transverse furrows, two others are marked by side furrows, and there is a jjosterior lobe twice as long as wide, not reaching the marginal fold. The side lobes are tumid and are traversed by transverse furrows ; three in front have the appearance of anchylosed seg- ments of the thorax ; one behind is less distinct, and a fifth is faintly indicated. A low, narrow, obscure fold goes around the margin of the shield. Sculpture. — There are minute scattered tubercle on the cheeks and glabella, and minute, rather obscure crenulations on the inner surface of the test at the marginal fold. The supposed pygidium is minutely granulated. Size. — Length of the head shield, 2 mm.; width, 1^ mm. Horizon and Locality. — In the fine gray shales of Div. Ic^ at Hanford Brook and Porter's Brook, St. Martin's, N. B., Canada. This species has a general resemblance to M. acanicus of the Swedish Paradoxides beds as regards the head shield; but if the pygidium described above belongs here, the species is more nearly related to M. Dawsoni and M. Schucherti; the crenula- tions of the margin are similar to those of the section Eodiscus, but not so sharply marked or so noticeable. MicRODiscus Dawsoni, Hartt. Plate xvii.-, figs. 5 a to e. Microdiscus Daicnoni, Hartt. Acad. Geol., 2d ed., }). 564, fig. 228. Microdiavus Daivsoni, Walcott, U. S. Geol. Surv. Bull 10, p. p. 23, pi. ii., figs. 3 and 3a. Microdiscus Dawsoni, Trans. Roy. Soc. Can., vol. iii., pt. iv., p. 75, pi. vii., figs. 11, a to c. Description. — " Cephalic shield semilunar, with thickened border, crossed by numerous grooves running perpendicularly to the circumference. Glabella convex, narrow, rounded in front, conical and pointed behind, projecting beyond the posterior border, without furrows or occipital groove. Cheeks convex, no eyes and no traces of sutures, posterior angles of the shield with backwardly projecting spines. Pygidium subti'iangular, with curved outlines, rounded in front and behind ; middle lobe distinctly marked and divided into six segments ; lateral lobes also divided ; furnished Avith a narrow border." This is one of the most characteristic species of the P. lamel- .-m 241 TRANSACTIONS OP THE [may 18, ii!ii' latus Subzone. The head shields in my examples are broadly semicircular ; the glabella and cheeks slope downward in front below the level of the anterior marginal fold, which rises in front as a prominent, crenulated, transverse ridge ; the glabella ex- tends backward into a stout spine, slightly hooked downward at the extremity ; the glabella and spine form together a fusiform axial lobe tapering to both ends, and the two parts are nearly on the same plane. The thorax consists of two joints having rounded I'ings an.i the pleurje have broad furrows directed forward as in Agnostus. The pygidium is angled in front, has seven segments in the rachis and five ribs on the lateral lobes, of wiiich the posterior are strongly directed backward as on the Welsh M. sculptus, Hicks. Sculpture. — This species is closely granulated on those parts of the test that are raised above the general surface, but not in the furrows. Size. — Length of head, exclusive of spine, 3 mm.; width, 4 mm. Length and width of pygidium, the same. The occipital spine is 2 mm. long. Horizon and Locality. — Tiie fine gray siiales of T)iv. 1 c^ at St. John, Ratcliff Stream, Simonds' and Hanford Brook, St. Mar- tin's, N. B., Canada, but nowliere plentiful. Development of the Yonng. — The young head shield in this species diH'ers widel}^ from tiie adult. At the length of 1 mm. the front rim is narrow all around and no crenulation is visible ; the chei'ks are comparatively flat, ajid there is a Hattened area Avithin the rim indented with a depressed point in front of the glabella, which it touches as in M. Srhncherti. The glabella is pointed behind but bears no spine. The genal angles are some- what |)ointed. At \\ mm. length of head shieUl, the rim begins to witlen in front and shows shallow crenulations, and the flat- tened area still sliows a depression in front of the glabella. Tiie genal angles are sliarp and the posterior marginal fold broadens at tlie end and is upturned as in M. Schucherli. The glabella has a long anterior lobe, as M. >i])cciosu>i has in the adult stage. In the later moults the strongly crenulated widened margin and the development of the occipital spine easily distinguish this species from the former of those above named, and the breadth of the shield and wide anterior rim from the latter. I have not met with the genal spines described by I'rof. TIartt, but the indrawn and upturned genal angle of the head shield forcibly recall similar features in more than one species of Microdiscus of the Olenellus Zone. 1896.] NEW YORK ACADEMY OF SCIENCES. 242 Although the pj^gidium of our species and that of M. sculptus are alike, the head shields are quite different, and the number of thoracic joints differs. MicRODiscus PULCHELLUS, Hartt. Plate xvii., fig. 8 a to/. Microdiscus piinctatus (Salter) Whiteaves. Am. Jour. Sci., 3 ser., vol. xvi., p. 225. Microdiscu» jmlchellus, Hartt, Ms. in List to Sir J. W. Dawson. Microdiscus piinctatus, Walcott, U. S. Geol. Surv., Hull. 10, p. 24, pi. ii., figs. 1 a to c. Microdiscus punctatus vai*. pulchellus, Trans. Roy. Soc. Can., vol. iii., pt. iv., p. 74, pi. vii., figs. 12 a, b and a. Description (by Mr. C. D. Walcott). — " Head semi-elliptical in outline, rather strongly convex, and bordered on the front and sides by a depressed furrow and raised rim, the furrow contain- ing numerous short furrows perpendicular to the margin, as in 4/ Daiosoni, but not as strongly marked. The posterior border is strong back of the cheeks, and has the furrow continuing from the sides; a very narrow rim extends back of the glabella; eyes and facial sutures encirely absent. " Glabella elongate conical, extending backward in a strong spine, as long as the glabella in medium-sized specimens, and nearly' as broad at the base. In some examples the spine is shorter and smaller. The glabella rises above the level of the chocks, and is about three-fifths of the length of the head, bor- dered by stronjf dorsal furrows that are connected in front by a straigiit furrow with the depressed groove within the anterior marginal border, perceptibly nuirked by two pairs of oblique glabellar furrows in some examples. Cheeks convex, prominent, strongly defined by the dorsal and Vnarginal furrows. " Thorax unknown." [see below]. " The pygidium, associated with the head of this species in great numbers, has the same general outline as the head. The nil rrow. margined rim is well defined all around, widest at the sides; anterior marginal furrow very distinct; median lobe elongate conical, extending back nearly to the marginal groove ; nine anchylosed segments are indicated by eight rather strong, transverse furrows ; lateral lobes strongly convex, no furrow appearing back of the anterior marginal groove." Sculpture. — " Surface finely punctate, tiie punctre being rather large as compared with the ilepth. Size. — Dimensions of ii rather broad head. Length, ii.5 mm. (also 4^ mm.). I'ygidiuiu, length, 3.75 mm. (also 4^ mm.). 243 TRANSACTION'S OF THE [may 18, Breadth, 5 mm. There is considerable variation in the propor- tion of the parts. " This is an abundant and well-marked species. The pygidium is very similar to that of M. speciosus, Ford, of the Olenellus Fauna. In event of the two forms M. punctatus and M. pulchel- lus proving distinct, I propose that Mr. Hartt's name, M. pul- chellus, be given to the American species. The following particulars may be added to the description of this form given by Mr. Walcott, in Bulletin 10. The occipital spine is much more slender in the author's ex- amples than in those figured by Mr. Walcott ; it is flattened at the sides, and frequently rises from the plane of the head shield at an angle of 45°. The slxort, transverse furrows on the marginal fold of the head shield differ from those of M. Dawsoni in being closer to- gether and at about equal distances all around the margin ; they are not on the outer surface of the fold, but only indent the inner surface of the test, hence they arc not visible from above when the test is perfect. No complete thorax has been found in connection with the shields, but the separated joints show a strong axial ring which has a row of obscure tubercles along the ridge similar to those on the posterior rings of the rachis ; the pleurne are strongly arched, and have a long and deep furrow directed somewhat obliquely backward ; they seem not very rigid and terminate in rounded points. According to Mr. Walcott the median lobe of the pygidium has eight segments, including the articulating ring, but well grown examples show nine well marked rings, and three other smaller, less distinct ones, near the end of the rachis. When one-quarter grown this species has seven distinct rings in the rachis, the number in the malure M. punctatus, according to Mr. Salter. From this species M. pulchelluK differs not only in re- spect to the number of these rings, but also in having a smaller and more erect occipital spine. Sculpture. — The test of M. pulchelhiH has been described as punctate, but this remark applies only to the head shield and thorax, for the pygidium is tuberculatc on the side lobes. It may be added that the strong rings of the rachis carry eacii a low spine at the Humniit ; but on the weak posterior rings the crest is ornamented with a row of small tubercles. Size. — The dimensions given above are of the largest shields, more frequently it is a third smaller. Development of the Young. — The change of this species as it grew from a Protaspis stage similar to that of other trilobites "Nla 1896.] NEW YORK ACADEMY OF SCIBNCES. ^44 associated with it, is partly shown by immature tests that have been observed. It acquired generic characters at a ver^' early stage so far as the head shield is concerned, but the pygidium took a longer time. The Pi'otaspis (slightly over ^ mm. in length) is remarkable for the equal spacing of the somites al- most from the first, causing the first somite to be smaller, and the first furrow further forward than usual ; while the cephalic portion of the axis is visibly segmented, the caudal is not, and the line of suture between the two shields is scarcely indicated ; the rachis almost touches a faintl}' defined rim at the back of the shield. In the ^ mm. stage of the head shield the glabella is already near the normal form in the adult, but ex- tends farther forward, and the furrow in front is short and deeply impressed, as in the young of M. Dawsoni and the adult of if. Schucherti; there is a slender occipital spine elevated at an angle from the plane of the head shield as in the adult. When the head shield is 1 mm. long the crenulation on the in- terior of the front rim of this shield becomes visible, and very short genal spines are added to tiie posterior angles. When the pygidium was ^ mm. long it had three lobos in the rachis and one rib marked off by a faint furrow at the front of the lateral lobes ; this furrow is distinct only in the middle of its length ; at this stage the shield is much flatter and wider than the adult and is bordered by a broad rim, within which is a broad rounded furrow. The f mm. shield does not differ much in form, but has four rings in the rachis, and the rib at the front of each cheek is more distinctly marked. In the 1^ mm. stage there are seven lobes to the rachis and only a fnint trace of the rib on the front of the side lobe. In the 2 mm. stage there are seven strong lobes and three faint lobes on the rachis, and no trace of the rib on the side lobe, so that at this stage the pygid- ium has nearly assumed the aspect of the adult shield. Horizon and Locality. — All parts of the St. John Basin, in the beds carrying the Abenacus Sub-fauna I)iv. 1 d*. Also in Kenncbecases and Long Reach Basins at the same horizon. MiCRODiscus PiiNOTATUs, Salter. Mc?'orfr«c«8pH)!C/a»vldiH fSub/.one, ImvlnK the surCiico tnlicrcnliito ; the species Iihh not been ilelernilnod. mk%»m- 1896.] NEW YORK ACADEMY OP SCIENCES. 246 Mag. -V. P^rom Div. 1 c, St. John, N. From Div. 1 tl\ St. Martin's, N. Fig. 2. S. concentnca var. radiata. B. See p. 202. Fkj. 3. Stenotheca Hickaiana. Mag. 4- B. Seep. 205. Fio. 4. Stenotheca triangularis, a, a cast of, showing the outline of the cone and the thickened apex, b, a cast without the outline. Both mag. f From Div. 1 c^ St. John, N. B. See p. 203. Fio. 5. Strohilepis spinigera, J. M. Clarke. Terminal plate (and penulti- mate plate in outline). Fignred for comparison from Dr. Clarke's restora- tion. Mag. f . The terminal plate is partly covered by the penultimate. Devonian species. See p. 203. Fig. 6. Stenotheca nasuta. a, small example, mag. f . b, original type mag. f Both from Div. 1 c, St. John, N. B. See p. 204. Fi(<. 7. Plumiilites Stanuelensis, n. sp, mag. f . From Div. 1 rf', Manuel Brook, Newfoundland. See p. 200. ( Misprinte From Div. 1 d\ St. Martin's. See p. 214. Fio. 3. Agnoetus parvifrona Linrs. var. tesaella. a, head shield, b, thoraz.^ c, pygidiam, Mag. f. From Div. 1 d', St. Martin's, N. B.. See p. 221. Fio. 4. Agnostua umbo, a, head shield, b, pygidiam. Mag., |. From Div. 1 d», St. Martin's N. B. See p. 222. Fio. 5. Agnostua obtuailobua. Mag. {. From Div. 1 d>. St. Martin'a N. B. See p. 223. Fio. 6. Agnostua Davidia, Hicks. Pygidiam. Mag. f . From Div. 1 d\ Manael Brook, Newfoundland. See p. ^5. Fio. 7. Agnostua gibbua, Linrs. var. partitua. Uead shield. Mag. f > From Div. 1 c«, St. Martin's, N. B. See p. 227. Fio. 8. A. gibbua var. acutilobua. Mag. f . From Div. 1 (i<, St. Mar- tin's, N. B. See p. 227. Fio. 9. Agnostua Nathorsti, Briigg, var. cot^uena, n. var. a, head shield. (, pygidiam. Mag. f . From Div. 1 d\ St. Martin's, N. B. See p. 230. Fio. 10. Agnostua flsaua, 'Landgr. var. tfiftaaua, n. var. Mag. ^. From Div. 1 rf', St. Martin's, N. B. See p. 231. Fio. 11. Agnostua punctuosus, Ang. a, head shield, b, pygidiam. Mag. f . From Div. 1 d'. Highland Cove, Newfoundland. See p. 232. PLATE XVII., AoNOSTUs and Miobodiscub. Fio. 1. Agnostua Imvigatua, Dalm., var. terranovicus, n. var. a, head shield. 6, pygidiam. Mag. |. From Div. 1 f{>. Highland Cove, New- foundland. See p. 233. Fio. 2. A, Imvigatusyat. mammilla, w.yat. a, head shield, b, pygidinm. Mag. f . From Div. 1 d*, Highland Cove, Newfoundland. See p. 236. Fio. 3. A.liBvigatus\i%r.eiceroidea,n.\Skr. a, head shield, b, pygidiam. Mag. f . Found with the preceding. See p 234. Fio. 4. Microdiacus Schucherti u. sp. a, head shield, b, pygidiam. Mag. 4. From Olenellus limestone, Troy, N. Y. See p. 238. Fio. 5. Microdiacus Dawsoni, Hartt. n, head shield, b, same in profile, c, pygidinm. Mag. f. (f, young larval stage, head shield. Mag. ^■^. e, next larval stage, head shield. Mag. '1*^ AH from Div. 1 c', St. John, N. B. See p. 240. Fio. 6. Microdiacus specioatta, Ford, head shield. Mag. f. From Olenellus limestone, Troy, N. Y., figured for comparison. See p. 230. Fio. 7. Microdiacua precursor. Head shield. Mag. f . From Div. 1 c', St. Martin's, N. B. See p. 230. Fio. 8. Microdiacus pulchelhta Hartt. n, head shield, b, same in profile, c, pygidium. Mag. f. d. embryonic or Protaspis stage. Mag. *{. e, early larval stage. /, pygidiuni of same. Both Mag. ^^. Al! from Div. Id', St. Martin's, N. B. See p. 242. -M4r- I '5!'if ill ''■".: i'i;L Div. Div. Div. Fig. Mag. |. PLATE XIV., CiRBiPEDiA, Etc. Notation of the horizons, used below : Div. Ic'. Horizon of Paradoxides lamellatus. Ic^. Horizon of Paradoxides Eteminicus. Id'. Horison of Paradoxides Abenaous. Id*. Horizon of Paradoxides Davidis. 1. Stenotheea coneentrica. Flattened and crooked along the back. From Div. 1 d', St. Martins, N. B. See p. 201. Fig. 2. S. coneentrica var. radiata. Mag. V. From Div. 1 c, St. John, N. B. See p. 202. Fig. 3. Stenotheea Hicksiana. Mag. f . From Div. 1 d\ St. Martin's, N. B. Seep. 205. Fig. 4. Stenotheea triangularis, a, a cist of, showing the ontline of the cone and the thickened apex, b, a cast without the outline. Both mag. 4. From Div. 1 c«, St. John, N. B. See p. 203. Fig. 5. Strobilepift apinigera, J. M. Clarke. Terminal plate (and penulti- mate plate in outline). Figured for comparison from Dr. Clarke's restora- tion. Mag. |. Tlie terminal plate is partly covered by the penultimate. Devonian species. See p. 203. Fig. 6. Stenotheea namta. a, small example, mag. f . b, original type mag. f . Both from Div. 1 c, St. John, N. B. See p. 204. Fig. 7. Plumulitea Mannelcnsin, n. sp, mag. f . From Div. 1 d', Manuel Brook, Newfoundland. See p. 200. (Misprinted Plate XV. on p. 200. ) Fig. 8. Cirripedian and other plates. Type A, a and b, two forms of oval plates. Type B, a, ribbed plate ; b, smooth plate. Type C, a, plate with deep furrow ; b, plate with high umbo; c, plate with eared flange ; d, plate simi- larly flanged but more regular ; these are perhaps Cystidian. Type D, sym- metrical plate, perhaps one of the axial row of plates. Type E, triangular plate with radiating ridges (possibly cystidian). Type F, triangular plate with arched keel {Cirropodites Cambrenm). Type G, triangular plate with facetted edges. All the flgures except 8 G, a, mag. <|^ 8 G, a, is mag. ^. The narrow flgures beside the larger ones are sections. See p. 200. Trans. N. Y. Acad. Sci. Vol. XV., Pl. XIV hi .-U 7 J„ ^e* ill immmmmmmmmm nn-m nwiM M w u iiH i ii [O iii lW»Ml il> «i ->wn8n»MTW lfM»" PLATE XV., OsTRAcoPA and Agnostus (part). Fig. 1. LepUUtta ulata. a, outer surface of left valve. It, cast of interior of right valve. Mag. Y. From Div. 1 c^, St. Jolin, N. B. See p. 194. Fig. 2. Lepiditla curia. Interior of left v; ^'e. Mag. ^{'. From Div. 1 dK St. Martin's, N. B. See p. 195. Fig. 3. Lrpiditta auriculata. a, left valve showing faint concentric lines and the ligamental (?) groove at the hinge, b, same, hinge line in prolile. Mag. f From shales of Div. 1 c, St. Martin's. See p. 196. Fig. 4. Aluia flexilis n. g. etsp. left valve (with lower margin restored) showing ocular (?) tubercle, Mag. f. From conglomerate limestone hand in Div. 1 c', St. Martin's, N. B. See p. 198. Fig. 5. Pn'mitia Acadicn. a, left valve. 6, longitudinal section, c, trans- verse section. Mag. f . From Div. 1 e', St. Martin's, N. B. See p. 196. Fig. 6. Agnostm f(dlax var. vir. Complete, somewhat flattened. Mag. J. From Div. 1 c\ St. John, ]*. B, See p. 215. Fig. 7. A. faltax Mir.roticinnm. «, head shield, ft, a joint of the thorax. c, Pygidiuni. Mag. f. From Div. 1 d\ St. Martin's, N. B. See p. 216. Fig. 8. Same variety, a, head shield of young larva retaining embyouic (Protaspis-like) features. Mag. -,'• ^t you"S pygidiuni showing somites and posterior tubercle on rachis, effaced in later stages. Mag. V". Both from Div. Id', St. Martin's, N. B. See p. 216. Fig. 9. A. fuUax var. trilobalus, n. var. Pygidiuni Div. 1 c', St. John, N. B. See p. 216. Fig. 10. Agnoatuit Acadicm, Hartt. i,i«liuiii. Map From Div. t (■■'. Soo p. 'Ji;{. Kid. Aijiioxtiis irx Iiiiir. var. Iniiisivtiix n. var. I'y^idiimi, Mug. I'roin Div. 1 ii\ St. Aiartin's. See j). !21 1. Fi(i. ;?, AijiioshiK piirrifioiiK Iaiuh. \i\r. (issillii. «, htwl shield. /*, thora.x. (', i>.vjii«lium, Majj. i- From Div. 1 . AifiiostiiK ohliiKilohiis. Majjf. N. 15. See p. •»»-j:5. Fill. (>. Ai/iioslitu Ihtridix, Hicks. I'.vjiiidiuni. Majj. Mannel I5rook, Newfoundland. See ]>. :i2't. uni. May From From Div. 1 .VKidium. Mag. FrcHn Div. 1 (/', St. Martin'.s, N. 15. See p. i>:5(». From Fid. 10, Ai/iionliin Jissii.i, l.undgr. var. Iiiji.i.^iin, n. var. Mag. Div. 1 il\ St. .Martin's, N. J5. See p. ',>:51. Fid, 11. Aijiioxliix piiniliiosiis, Aug. a, head fthield, /', ))ygidiiim. Mag, i'. From Div. Id', Highland Cove, Newfoundland. Seep, .'!;5',*. tJ ' .V ' l ' t 't«MI TiiANs. N. Y. Acad. Sci. Vol. XV., Pl. XVI. 11 It PffffT*^ I'L.VTM XVII., AoNosrrs and Mkjkodiscus. I'Ki. 1. .l,/,wsl,ts nrri!,„l„s, Diilin., var. tnnnionrux, n. var a |„"i.l «lnol.l. /,, p.vKi.li,,,,,. Mag. j. r,,,,,, „i,, , ,/., i,igi,ia,„l Cov,.,' Now fomullaiid. See p. 'j;{;{. I'm.:-'. .i.l!rni,„l,(x\nr. worn, nillii,u. Mix: a, Iioad .slii..],]. /,, j.ygidimi. Man. f. iMoin Div. 1 ,1', lliglilaiul Covo, Nrwroniulland. Sec p. -jri. Fi(i. :?. .(.A7r,>,/«,s.var.W(v/vm/rN, „. var. „, Load shield. //, pyKidimi. iMiiK. ,. I'oiind witli (lit> pmrdiiif-. See p -JIM. ri»i. I. Mhro,lixr„s Sr/,i,r/wrli n. sp. „, lu'a.l sliiol.l. /,, py»idim„. IMafi. |. I'rom Olonellus limos((>iu>, Troy, N. Y. Kt-i- j). 'J.tS. n.J. 5. .1//,.m//,s<'«s /)„»N„<,/, Hartt. „, lim.l shiHd. />. sjunc in pn.iil,. 'S l>VKidiun.. Ma?.-, f. ,/, .v<.miK larval sta«v, head .sl.iol,!. Ma-r i," '■. iu-.vt larval staj-o, head .shield. Mag. ',". ,V11 IV,,,,, Djv. I ,.. st ?l„hn N. I?. See p. 'JU). ' Vui. (i. Mi,r,„lisri,s s,uvi„.s,(s, \\m\. head shield. Mag. ■{ Fr„i„ OleiH'llns lin.estt.ne, Troy. N. V., lig.ired for e...ni«irison. See p. ^>:{(). I'lo. 7. Mirnxlisriis privin-sor. Head shield. Maji. «. F,.,,,,, Div 1 e^ St. Martin's, X. 15. See p. ^!;!<). ' ' I'Ki. S. Micnullsnis p„Mwllux Ilartt. „, hea.l shield. /,, .same in prolll... '■, I..vw.'liun.. .Mag. ,'. ,1, en.hryonie ..r I'n.taspis sla.-v. Ma-r -" '■, oarly larval stage. /, pygi.li,„n of s.n.e. Moth Mag-. -;'." All fnMn"I)i'v." 1'/'. St. Martin's, N. ]\. See p. '.M J. Thanh. N. Y. Acak. Sci. Vol. XV., Pi,. XVII. id 6c fid Sc Sf i