LIBRARY OF THE UNIVERSITY OF CALIFORNIA. BIOLOGY class LIBRARY G *L _ A _ . / Jl_f-v* A. RA or THE UNIVERSITY PAPERS READ. ON SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM COLLECTION. BY W. M. BALE, F.R.M.S. (PLATES XII.-XXI). The species of Hydroida treated of in the present paper were (with one exception) included in a collection sent to me by Dr. Ramsay, from the Australian Museum, about theendof the year 1886. Besides a number of new species there were represented several which had previously been very imperfectly known, for one of which the Ceratella fusca of Gray- I have found it necessary to constitute a new family. Among the other specimens were a number of Dr. von Lendenfeld's types of the species described by him in the Linnean Society's Proceedings, several of which prove to be identical with species previously known. I have to thank Mr. T. Whitelegge, of the Australian Museum, for forwarding me addi- tional specimens of some of the species, and also for notes of his examination of some of those in the Museum. The type specimens from Dr. von Lendenfeld's collection, include the following the references being to the Proceedings of the Liniieau Society of N.S. Wales, Vol. IX. SERTULARELLA MICROGONA, von Lendenfeld. P.L.S.N S.W. IX., p. 416, PI. VII., figs. 1-3. (See page 763). DIPHASIA SYMMETRICA, von Lendenfeld. I.e. p. 414, PI. VIII., fig. 7. This is identical with Sertutaria bispinosa, Gray. 1 42022 746 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, SERTULARIA FERTILIS, von Lendenfeld. I.e. p. 406, PL VII., figs. 4-5. This supposed species is founded on specimens of a Thuiaria (T. sub-articulata, Cough trey), from which the brittle hydrothecse have been broken away. The portions figured as hydrothecae are not really such, but only the projecting portions of the hydro- caulus on which they have been supported, and the apparent teeth on the outer margins are merely remnants of the front of the hydrotheca, which are frequently left adhering when the rest of the cell is lost. I figure on Plate XVIII., fig. 8, a fragment of one of Dr. von Lendenfeld's type specimens, in which one of the hydrothecse is preserved. I have another specimen from New Zealand, differing from Dr. von Lendenfeld's in the much lighter colour, and in this also most of the hydrothecse are lost or injured. Professor Allman describes T. sub-articulata (under the name of T. bidens) as having two teeth on the inner side of the hydrotheca and the rest of the margin smooth, while Mr. Coughtrey says that there are two teeth on the outer side, in addition to the inner two. The outer teeth are present in all the cells which I have seen, but it is often difficult to distinguish more than one tooth on the inner side. PLUMULARIA GRACILIS, von Lendenfeld. l.e. p. 476, PL XIV., fig. 17 ; PL XVII., figs. 28-29. The type is a specimen of P. Ramsayi, Bale. Neither the detailed figure nor the description agrees with the specimen, which does not possess a mesial sarcotheca above the hydrotheca on the same internode, as represented. PLUMULARIA RUBRA, von Lendenfeld. l.c. p. 476, PL XIII., figs. 11-12; PL XIV, fig. 15. (See page 778). BY W. M. BALE. 747 PLUMULARIA TORRESIA, von Lendenfeld. Ic. p. 477, PL XIII., figs. 13, 14 ; PI. XIV., fig. 16 ; P. campa- nula, Busk. (See page 776). PLUMULARIA TRIPARTITA, von. Lendenfeld. I.e. p. 477, PI. XII., figs. 8-10. =P. setacea, Ellis. (See page 778). PENNARIA ROSEA, von Lendenfeld. l.c. p. 594, PI. XXIV., figs. 4042. This species is, as Mr. Whitelegge has pointed out to me, identical with the P. australis of the Catalogue of the Australian Hydroid Zoophytes. I have described this species as having 7-12 filiform tentacles, and 9-14 capitate ones, while P. rosea is stated to have 30-40 and 20-30 respectively. The discrepancy (especially in the number of the filiform tentacles) is very great, and I cannot account for it. I have examined many hydranths (including terminal ones) both from my original specimens and from Dr. von Lendenf eld's types, and have not succeeded in finding any with a larger number of tentacles than I have recorded, except in one or two cases where the number of capitate tentacles reached about 17. Mr. Whitelegge has kindly examined a number of specimens with the same result. The figure which accompanies Dr. von Lendenfeld's description shows a hydranth with not more than 10 or 12 capitate tentacles. I have not found the proboscis or oral portion separated from the rest of the body so sharply as shown by Dr. von Lendenfeld.* P. australis is very closely allied to P. symmetrica, Clarke, the polypary especially so ; but the hydranths of P. symmetrica are ovate, not flask-shaped, and have about 30 capitate and 14-18 filiform tentacles. *Dr. von Lendenfeld has a note, to which reference is wanting, at the foot of the page containing his description of P. rosea, referring to page 45 of the "Catalogue " (the description of P. australis] ; it is evident, there- fore, that he intended at first to refer his specimens to that species, where they undoubtedly belong. 748 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, OBELIA AUSTRALIS, von Lendenfeld. I.e. p. 604. (See page 753). DIPHASIA RECTANGULARIS, von Lendenfeld. I.e. p. 914, PI. XLL, figs. 6-8. This is synonymous with Idia pristis, Lamx. Fig. 7 shows part of a pinna with the hydrothecae separated, but there is nothing of the kind in the type specimens, which are quite similar to that figured in the " Catalogue." The gonothecae also agree with my former specimens, and not with Dr. von Lenden- feld's figure. EUCOPELLA CAMPANULARIA, von Lendenfeld. (See page 751). A few other species were represented, but the specimens were too fragmentary, or not sufficiently well preserved, to be of much value. CERATELLID^E. Hydranths naked, sessile on processes of a chitinous reticu- lated polypary, tentacles all capitate, scattered irregularly over the body. Gonosome unknown. CERATELLA FUSCA, Gray. Hydrophyton forming a much ramified compressed structure, resembling a Gorgonian coral ; polypary chitinous, of a dark brown colour, and of a finely reticulated structure, the main stem finally becoming very thick and irregular in form ; branches gradually smaller towards the ends, very numerous and crowded : hydro- phores (bracket-like projections of the hydrocaulus, which support the hydranths) arranged in a somewhat irregular sub-spiral manner round the branches, formed by slightly radiating ribs united by perforated laminae, the ribs projecting at the outer margin ; meshes of the polypary filled with ccenosarc. ttydranths ovate, sessile BY W. M. BALE. 749 on the hydrophores, erect, armed with a number (about 8 or 10) of short capitate tentacles, which are scattered over the body without definite order. Additional localities Off Port Jackson Heads : Broughton Islands. Mr. Brazier has already recorded in the Proceedings of the Linnean Society of N. S. Wales for 1886, page 575, the occurrence of C. fusca (not previously recognized since its original discovery by Gray) at various localities near Sydney, including Bondi Bay, where it was first obtained. Mr. Whitelegge informs me that it is found on Laminaria-roots. From examination of a specimen which had been preserved in spirit, I find that the hydranths are not formed on the same type as those of Hydractinia (in which there is a single circle of fili- form tentacles surrounding the base of a conical proboscis), but are armed with capitate tentacles only, which are distributed irregularly over the body. Ceratella must therefore be removed from the Hydractiniidse, to which family it was assigned by Mr. Carter, in the absence of the hydranths, and must form the type of a new family the CERATELLID^: -allied to the Corynidse by the structure of the hydranths, and to the Hydractiniidae by their sessile condition and by the character of the polypary. This how- ever is not quite the same as in Hydractinia, being distinguished by its free and erect growth, as well as by other peculiarities. The basis of the structure (as seen in the new extensions at the ends of the branches), is a reticulated chitinous tissue, so like the skeleton of some of the horny sponges that a portion broken off and examined separately might well be mistaken for sponge-tissue. As growth proceeds this substance becomes denser and closer, and the superficial fibres in some parts usually run parallel, so as to leave channels between them. This is especially the case with the under side of the projections on which the hydranths are supported, to which I have applied the term " hydrophores," originally used by Professor Allman for the calycles of Halecium. These are formed by a number of longitudinal ribs which run along the 750 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, branch for some distance, and are continued outwards in a bracket- like form, spreading somewhat apart and united by chitinous matter which forms a sort ot web with numerous perforations, so that the outer or lower side of the hydrophore presents the aspect of a number of channels bounded by the ribs, and having perforated or reticulated floors. On the upper side of the hydro- phore further reticulations exist. When the polypary with the eoenosarc is examined by reflected light the whole mesh of the polypary is seen to be tilled with the whitish ccenosarc, with the edges of the superficial fibres everywhere showing as a fine brown reticulation. The hydranths are stout ovate bodies like those of the genus Coryne, very little narrowed below, and seated directly on the hydrophore. I found a difficulty in counting the exact number of tentacles, owing to the specimens being imperfectly pre- served, but there appeared to be usually about eight or ten, four or five of which generally surrounded the oral extremity, while the others were variously scattered over the body, one or two being often found quite close to the base. The capitula are large and globular, with such short stems that they appear almost sessile, but this may be caused by the contraction of the tentacles after death. The eoenosarc contains numerous thread-cells, somewhat similar to those of Hydra, but larger. The polypary generally attains a height of about three inches, and is sometimes slender throughout, arid beset with hydrophores for most of its extent, but in other cases the stem and principal branches are very thick and without hydrophores. Doubtless as the organism increases in growth the older portions become enveloped in fresh layers of ccenosarc, covering the hydrophores and forming a thick trunk as in the ordinary fascicled hydroids. The newly-formed terminal portions of the branches are compressed in a plane at right angles to that of the whole polypary. BY W. M. BALE. 751 EUCOPELLIN^E. EUCOPELLA CAMPANULARIA, von Lendenfeld. (Plate XIIL, figs. 9-15). This hydroid is no less remarkable for the structure of the trophosome than for the nature of the medusan gonozooid. I received portions of two gatherings, both from Bondi, but differing considerably in the form of the hydrothecse. The hydrorhiza is remarkably broad, with a much thickened perisarc^ giving off branches at right angles. The peduncles, which vary from the length of a hydrotheca to four or five times as long, are straight, and very thick and massive ; but the perisarc is thinned away at the base down to its junction with the hydro- rhiza, at which point the external diameter of the peduncle is but little more than that of the cavity which runs through it. The peduncle is rounded off at its summit, at which part the cceno- sarcal tube is somewhat enlarged, as it is also at the base. A single spherule intervenes between the hydrotheca and the peduncle. The hydrothecae are remarkable among the Campanularians by their bilateral symmetry Those of the variety which corresponds most closely with the type specimens are, as seen in their broader diameter, semi-ovate, with one of the narrower sides cut down a little lower than the opposite one, and the broader sides elevated. The margin is not everted nor toothed. There is no cavity corresponding to the external shape of the calycle, but the interior is filled up with a solid chitinous mass, leaving only a wide shallow depression at the top, and a narrow tubular passage to the base of the calycle. The hydnmth is therefore not retractile, but rests on the calycle, which furnishes a slightly concave support for it. The solid pait of the calycle is clear and transparent, yellowish in colour, and almost homogeneous. In the other variety the calycles are similarly solidified, but the lower part appears as if condensed and shrunken ; and the trans- parent homogeneous structure has given place to a woody-looking 752 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, tissue, with irregular superficial ridges running from the base upwards. The two narrow sides of the calycle-margin are curved outwards, so as to form thick solid everted lips, one of which is higher than the other. In Dr. von Lendenfeld's type specimens some of the hydrothecse are more deeply excavated, and he states that deep-water speci- mens have thick hydrothecae, while those from the harbour have thin ones. The specimens which I have described are, however, from the harbour. CAMPANULARIID^E. OBELIA GENICULATA, Linn. Additional locality. Middle Harbour, Port Jackson OBELIA ANGULOSA, n.sp. (Plate XII., fig. 3). Hydrocaulus monosiphonic, 1-2 inches in height, usually with numerous sub-erect branches given off from the main stem ; stem and branches more or less zig-zag, with a few rings or spiral turns (mostly 3-5) just above the origin of each peduncle ; peduncles ringed, those on the upper portions of the hydrophyton consisting of 2-4 i-ings, those on the lower portions often twice the length of the calycle, usually having the central part smooth ; hydrothecse alternate, funnel-shaped, generally slightly constricted at the level of the " floor," which is some distance above the base, and situated somewhat obliquely ; margin slightly everted, not toothed, somewhat uneven. Gonothecse urn-shaped, mostly very long and slender, with an elevated neck ; peduncle with about 3-5 rings ; upper part of the capsule often marked with faint, not prominent rings. Ova variable in number (often about 15), in two or three rows, or irregularly arranged. Gonozooids not observed. Hob. Parramatta River. BY W. M. BALE. 753 This species is found growing in tufts, tke largest of which among my specimens is about 1J inch high. Branches are given off, sometimes profusely, from the main stem, but no secondary branchlets were to be found, though possibly such might be produced on older specimens. Each internode of the hydrocaulus springs from a point immediately below the origin of a hydrotheca-peduncle, forming a rather sharp curve upwards ; and the upper part of the internode is very slightly curved outwards in the opposite direction, so that the stem or branch acquires a slightly zig-zag form. Thus instead of the peduncle of the hydrotheca being given off at an angle with the stem- internode which bears it, the peduncle is continuous with its internode in a direct line, and the next internode springs off at an angle. The hydrotheca when immature is entire, the summit being crowned with a watch-glass-shaped cap, which ultimately falls off, leaving the margin of the hydrotheca rather irregular or ragged-looking. The rings of the hydrocaulus are very distinct and regular, sometimes spiral, at other times simply annular. When the peduncles of the calycles are longer than would be equal to the width of nine or 10 rings, the central part is smooth. The gonangia are remarkable for the length they usually attain, compared with their small diameter, being often less in width than an average calycle, and more than three times its length. OBELIA AUSTRALIA von Lendenfeld. (Plate XIL, figs. 1-2). Primary shoots monosiphonic, about 1-1J inches in height, sometimes with a few small branches, stem and branches flexuous, with a few rings or spiral turns (mostly 3-5) just above the origin of each peduncle ; 8 or 1 rings usually at the base of each stem and branch ; peduncles ringed, those on the upper portions of the hydrophyton consisting of about 4-10 rings, those on the lower portions longer, often with 10-20 rings, or with the central part smooth. Hydrothecae alternate, somewhat obconical, or with the upper portion almost cylindrical ; not noticeably constricted at the 754 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, level of the " floor," which is a little above the base, and situated obliquely ; margin very slightly everted, not toothed, somewhat uneven. "The gonophores have the ordinary elongate shape At the time of liberation the medusa is similar to a newly-born 0. geniculata" (Von Lendenfeld). Hob. Eist coast of N. Zealand, Larninarian Zone. Dr. von Lendenfeld says of this species : " The stem of this Obelia is creeping, adnate to foreign bodies, to which it clings like a hydrorhiza. The stem bears hydranths on very short annulated stalks, and also a few very short branches with nearly sessile hydrothecse. These creeping stems are short, and take their origin from a distinct hydrorhiza, which differs from the creeping stem by the much greater thickness of its perisarc, and by the numerous anastomoses which cause it to attain a reteform appearance." I have not been able to verify this description, nor distinguish the " creeping stems " from a true hydrorhiza, but in any case the stems which bear the hydranths and short branches are not the " creeping stems," but the erect shoots. Dr. von Lendenfeld refers to this species (but apparently not with absolute certainty), an adult medusa which he found in large numbers in Port Jackson. The tentacles are said to be from 30 to 40, and the umbrella always in a reverted position. This is not the case with the young medusa3 which were obtained with the trophosome.* 0. australis is somewhat coarser and more rigid than 0. angulosa. It maybe distvguished from that species by the internodes of the stem, which are not abruptly curved outwards at their origin, but are more or less curved alternately in opposite directions through- out their whole length, so that the stem is flexuous. The hydro- thecse are less conical than those of 0. angulosa, without the distinct constriction at the level of the floor, which is also nearer the base of the cell, and rather more oblique. *On p. 920, Vol. IX., Dr. von Lendenfeld says, "I have described this species from the polyp-colonies and the young larvae which I obtained in Port Jackson." In the original description, however, the only locality men- tioned is the East coast of New Zealand. BY W. M. BALE. 755 CAMPANULARIA CALICULATA, Hincks. (Plate XIII., tigs. 1-3). Two gatherings of this species have been obtained from Port Jackson, iii one of which the calycles are for the most part wholly without the thickened wall which usually characterizes the species; occasionally however they conform to the type. In the other specimens, the calycles agree pretty closely with those figured by Mr. Hincks, and vary to about the same extent. The peduncles are exceedingly variable in length, sometimes being 16-18 times the length of the calycle. They may be closely undulated through- out, or almost smooth, the latter condition occurring principally in the longer peduncles. The gonangia contain two sporosacs, and are borne in extraordinary profusion, their number often greatly exceeding that of the hydrothecae. CAMPANULARIA CALICULATA, var. makrogona, von Lendenfeld. (Plate XIII., figs. 4-8). In this variety the hydrotheca-wall is thickened throughout, but more particularly at the base, and at the upper portion, where the chitinous substance forms an external band encircling the upper ^ or J of the calycle, very thick in the centre, and gradually thinned away above and below. In most of the hydro- theca? the cavity is exactly cylindrical, with a flat floor, but in some of them the internal diameter slightly diminishes downward. The margin is somewhat everted, and often becomes doubled or trebled by successive circles of growth. The peduncles are stout and usually very strongly undulated. I am not aware whether the very large gonangia characteristic of this variety are always associated with the peculiar form of hydrothecse which I have described ; if so, it may be questioned whether there is not sufficient ground for separating this form as a distinct species. 49 756 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, CAMPANULARIA (?) SPINULOSA, n.sp. (Plate XII., tigs. 5-7). Hydrorhiza slender, climbing ; hydrocaulus about -J inch high, slender, unbranched or with numerous sub-erect branches ; stem and branches nearly straight, with a few rings or spiral turns (mostly 4-6) just above the origin of each peduncle, 6-12 rings usually at the base of each stem or branch ; peducles ringed, those on the upper parts of the hydrophyton consisting of about 5-6 rings, those on the lower portions often with 8-10. Hydrothecse alternate, sub-cylindrical in their upper half, tapering below, slightly constricted at the " floor," which is a little above the base, and somewhat oblique ; margin armed with a number of minute slender compressed spines (usually 20-24) arranged in pairs, the margin very slightly sinuated between the two spines of a pair, more deeply sinuated (almost semi-circularly) between the pairs ; hydrotheca marked with faint longitudinal lines, one between every two pairs of spines. Gonosome unknown. Hob. Port Jackson, on a Tubularia. In the form of the hydrothecae, and the arrangement of their marginal teeth, this species is similar to a hydroid described by Clarke under the name of Obelia bidentata* but that species is polysiphonic and grows to the height of six inches, while the specimens of C. spinulosa, which I have examined, are of delicate growth and not more than half an inch in height. It is possible, though perhaps not probable, that the present species is a young form of 0. (?) bidentata ; at present it may be provisionally regarded as distinct. Most of the shoots exhibit the rudiment of a polysiphonic structure, consisting of a delicate stolon which originates from an aperture formed at the outer side of the base of the most proximal peduncle, and grows downward along the * Descriptions of new and rare species of hydroids from the New England coast. (Transactions of the Connecticut Academy of Arts and Sciences, Vol. III., Part I.) BY W. M. BALE. 757 original stem. When it reaches the object on which the zoophyte is growing it becomes attached thereto, and assuming the character of the hydrorhiza, gives off fresh shoots. In nearly all my specimens the downward growth of the supplemental tube was arrested by the death of the organism before it could reach the base of the stem, leaving it with an obliquely truncated extremity. CAMPANULARIA (?) SERRULATA, n.sp. (Plate XII., fig. 4). Hydrorhiza slender, climbing ; hydrothecae borne on long peduncles, which spring either directly from the hydrorhiza or from the side of other peduncles ; peduncles slender, with about 8-16 rings at the base and a less number (mostly 2 or 3) at the summit, smooth throughout the rest of their length. Hydrothecae large, campanulate, constricted at the " floor," which is raised above the base so as to enclose a nearly cylindiical cavity ; margin not expanding, armed with about 10-14 rather large, triangular, pointed teeth. Gonosome unknown. Hob. Port Jackson, on a Tubularia. This is a delicate species, with no proper stem, but the primary peduncles generally give origin to secondary ones exactly resembling them, the habit in this respect being similar to that of G. mar- ginata, a species otherwise very different to the present. The rings of the peduncles are distinct and regular, as in C. spinulosa. The specimens were less than half an inch in height. CAMPAXULARIA COSTATA, Bale. Near Peel Island, Moreton Bay, parasitic on Pasythea hexodon. (Mr. J. D. Ogilby). The aperture is more or less oblique in most of the specimens. Perhaps this species might best be placed in the genus Lafoea. 758 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, CAMPANULARIA MARGINATA, Bale. Bondi ; Coogee (plentiful), (Mr. T. Whitelegge). I have mentioned in the " Catalogue " that some of the hydro- thecae of this species have the remains of an operculum visible, but in these specimens the structure alluded to is not present. It is a very delicate membrane, and in the few cases where I have met with it was incomplete. It may probably be a temporary structure like that which covers the immature hydrothecae of various species of Obelia. LAFOEID^E. LAFOEA SCANDENS, n.sp. (Plate XIII., figs. 16-19). Hydrophyton parasitic on other hydroids ; hydrorhiza slender ; hydrothecee springing directly from the hydrorhiza, tubular, straight or slightly curved, rounded below to the level of the "floor," basal portion short, contracted, pedicle very short; aperture simple, margin very slightly everted, often double or triple. Gonangia about double the length and diameter of the hydro- thecse, tapering downwards in the lower half ; with more or less distinct transverse undulations; margin with three or four shallow emarginations ; summit of the blastostyle forming a trumpet- shaped expansion ; gonophores two, both on the same side of the blastostyle. Hob. Port Stephens; Port Jackson; mostly on Sertularella divaricata, var. sub-dichotoma. The specimens of Sertularella divaricate from Port Stephens were quite overrun by this species, its hydrothecae in some, paits equalling or even exceeding in number those of the Sertularella. So far as I am aware, it is the first species of Lafoea in which the gonosome has been observed. The gonothecse were fairly BY W. M. BALE. 759 plentiful, and in various stages of development ; those which were entire und unopened contained a slender blastostyle bearing two gonophores. The summit of the blastostyle is trumpet- shaped and apparently open, bnt no tentacles are present. The terminal portion appears to fall off before the maturity of the second gonophore ; at least it was absent from those capsules from which the primary gonophore had been extruded. The gonophore seemed to contain three or four large ova grouped above a stout spadix, but the specimens were not sufficiently well preserved to place the structure beyond doubt. The aperture of the ripe gonotheca, with its three or four emarginatious and corresponding opercular divisions, strongly resembles the aperture of the hydrothecse in some species of Sertularella. HALECIIDJE HALECIUAI GRACILE, n.sp. (Plate XIV., figs. 1-3). Hydrophyton slender, monosiphonic, attaining a height of about ^ inch ; hydrorhiza climbing over other hydroids ; branches some- what straggling, variable in length, stem and branches slightly flexuous, divided into moderately long internodes, by twisted oblique joints which slope alternately in opposite directions, each internode bearing a calycle close to its upper extremity. Calycles alternate, varying from almost tubular to funnel-shaped, and often with other calycles springing from within them ; margin expanding, strongly everted ; basal part of the calycle sometimes ringed. Gonothecse, female, large, ovate, compressed, sporosac decidedly narrower than the capsule, with a space at the upper part not occupied by ova : male smaller, club-shaped in outline. Hab. Port Stephens, on an Aglaophenia ; Port Jackson, on a Tubularia. This species differs from most others in being slender and monosiphonic. Each internode gives off primarily a single calycle, 760 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, and the branches originate at the sides of these calycles. When the soft matter is cleaned away there is usually visible a circle of puncta indicating the position of the base of the hydranth, and when a new calycle is formed within an old one it originates from this part, which is but a short distance below the margin. The base of the hydranth is usually flattened, and is united by a very slender isthmus to an offshoot of the ccenosarc which occupies the centre of the lower part of the hydrophore. Sometimes the branches are all short, and somewhat pinnately arranged, but in other specimens they are larger, occasionally equalling the stem in length. HALECIUM PARVULUM, n.sp. (Plate XIV., figs 4-5). Hydrophyton about J to J inch high, branches ascending, stem mid lower branches fascicled, stem and branches flexuous in the upper portions, divided into rather short internodes by twisted oblique joints, which slope alternately in opposite directions, each internode bearing a calycle close to its upper extremity. Calycles alternate, sub-tubular, often with other calycles springing from within them ; margin expanding, strongly everted, basal part of the calycle sometimes ringed. Gronotheca, female, large, ovate, compressed, with a large concave notch at the summit, sporosac similar in outline to the capsule, and nearly filling it, ova completely occupying the interior of the sporosac : male, not observed. Hab Bondi Bay. In the form and arrangement of the calycles this species differs little, if at all, from H. yracile, but may be distinguished from that species by the compound stem and shorter internodes, as well as by the difference in the gonosome. The specimens were growing on a small sponge, and a very intimate union existed between the sponge and the hydroid, the former having grown for some distance round the basal portions of the Halecium, and the sponge- fibres being closely and firmly adherent to the latter in all BY W. M. BALE. 761 directions. Mr. Whitelegge informs me that the specimens in the Museum are all similarly attached to the same species of sponge ; it is therefore probable that the association is a constant characteristic. SERTULARIID^E. SERTULARELLA DIVARICATA, var. sub-dic/wt&ma, n. var. (Plate XVI., figs. 3-4). Hydrocaulus about 6 inches in height, straggling, ramuli similar to the stem, given off irregularly, but in the same plane ; thicker portions of the hydrocaulus sometimes supporting more than one hydro theca on an internode. Hydrothecse tubular, adnate most of their height, free part slightly bent outwards ; aperture with three teeth, the superior somewhat recurved. Gonotheca? large, obovate, strongly annulated (9-10 rings), orifice very small, infundibulate, mostly excentric. Hob. Port Jackson. The trophosome differs from that of the typical S. divaricate, only in its habit, the ramuli being given off quite ii regularly and at long intervals, while those of the type are borne, *dth some exceptions, below every third hydrothecse on each side of the stem. The gonotheca? differ from those of the type simply in the small size of the orifice, which is like that commonly found in the Bass' Straits form of S. Johnstoni. SERTULARELLA DIVARICATA, var. dubia, n. var. (Plate XVI., figs. 1-2). Hydrocaulus 1-2 inches high, ramuli similar to the stem, given off irregularly but in the same plane, thicker portions of the hydrocaulus sometimes supporting more than one hydrotheca on an internode. Hydrothecee tubular, adnate most of their height, free part slightly bent outwards, aperture with three teeth, the superior somewhat recurved. 762 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, Gonothecae large, obovate, strongly annulated, (10-12 rings), orifice rather wide, infimdibulate, mostly excentric. Hab. Bondi Bay. This form might with almost equal propriety be assigned either to S. divaricata or to the southern Australian S. Johnstoni (if indeed it be not, as appears likely, one of a series of transition forms uniting the two). In the bushy habit and the compara- tively short internodes it rather resembles 8. Johnstoni, but its hydrothacse are more like those of S. divaricata, being adnate most of their length, and only slightly projecting forward. The peristome often consists of several successive growths. The gono- thecse are a little smaller than those of the type, with closer and more numerous rings ; the aperture is precisely similar. The polypary is much shorter and more bushy than that of the variety sub-dichotoma, but the pinnae or ramuli, as in that form, are given off at irregular intervals, so that the pinnate habit is lost. SERTULARELLA LONGITHECA, n.sp. (Plate XVI., figs. 5-6). Hydrocaulus slightly branched, divided by oblique joints into internodes which bear one or occasionally two hydrothecae. Hydrothecso adnate from J to J of their length, long, narrow, tubular, smooth, curved outwards, springing from the sides of the hydrocaulus or partly from the front ; aperture not contracted, with three large teeth, one superior and two lateral. Gonothecse rather large, without annulations, somewhat widened laterally, with a shoulder at each side of the aperture ; aperture small, tubular, not expanding. Hab. Port Denison. The only specimen I have seen was 2 \ inches high, and consisted of a monosiphonic stem with live or six simple lateral branches. The hydrothecae are toothed like those of the S. Johnstoni group, but are nearly double as loug in proportion to their diameter, while BY W. M. BALE. 763 the gonaugia are of a totally distinct type. Only one of the latter was present, which was slightly distorted, so that its exact form was rather doubtful, but it appeared to have two lateral wings terminating upwards in angles at each side of the aperture. SERTULARELLA MICROGONA, von Lendenfeld. (Plate XVI., fig. 8). Hydrocaulus simple, about 1 5 inch in height, composed of long, slender internodes which are abbreviated above close to the hydrothecaB, and are undulated somewhat spirally in their lower portions. Hydrothecae barrel-shaped, rather slender, somewhat contracted towards the aperture, with about three transverse rugae ; adnate of their height or somewhat more, directed out- wards and but slightly forwards ; aperture with four teeth and a four-sided operculuni ; three internal compressed vertical teeth, two of which are within the two upper emarginations of the border, and the third opposite the inferior marginal tooth. Gonothecse 1 Hab.PoYt Phillip. This species is a close ally of the S. tenella of Hincks, and is very slender throughout. The portions of the intemodes below the bydrothecsB are slightly waved, long, and tubular, often being fully double the length of the hydrotheca. The internal teeth are three in number, and are arranged precisely as in S. indivisa ; but as S. microyoHa has four marginal teeth, the internal ones do not alternate regularly with them, the lower one being opposite a marginal tooth, while the others are between the three upper marginal teeth. A close examination of specimens of S. polyzonias from Port Phillip shows that a similar arrangement exists in that species, though the internal teeth are so delicate and transparent that they are easily overlooked. Dr. von Lendenfeld says that the gonangia of S. microgona, are without rings, but his outline figure shows them transversely wrinkled. 764 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, SERTULARELLA VARIABILIS, n.sp. (Plate XV., figs. 5-9). Hydrocaulus simple or pinnate, pinnae when present alternate,, given off just below each hydrotheca on the stem ; stem and pinnae divided by twisted joints into internodes, each bearing a hydrotheca on its upper part. Hydrothecse adnate from J to J their height, divergent, both series directed towards the front or all nearly in the same plane, with several more or less distinct trans- verse rugae, contracted near the aperture and swollen below ; aperture with three marginal teeth, one superior and two lateral, also with three internal compressed vertical teeth alternate with those of the margin, or sometimes with three teeth within the lowest side and one within each of the other two sides. Gonothecse ovate, with transverse undulations which vary greatly in number and distinctness, and are often absent from the proximal part ; summit tubular, with from two to six teeth, and a small circular aperture. Hob. Bondi ; Coogee. With some hesitation, I include under the name of S. variabilis a series of forms allied to (and partly intermediate between) the S. indivisa and S. solidula of the southern coast. The form which may be regarded as the type differs from S. indivisa mainly in having the internodes and hydrothecse stouter and comparatively shorter, so that for the most part each hydrotheca is nearly or quite in contact with the lower part of the next internode above, while in S. indivisa the intern odes are slender and elongated, with the joints consisting usually of double oblique constrictions, so that the hydrothecse are more widely separated. The hydrothecse in the present form are also larger, and both series are commonly, but not invariably, directed towards the front, instead of lying in the same plane. The other principal type represented in the collection seems more apt to assume the pinnate form, and would not be suspected of any very close affinity with the first variety if it were not for the occurrence of intermediate forms. The BY W. M. BALE. 765 hydrothecse are smooth, or nearly so, and the constriction below the aperture is absent or very slight on the outer side, while it is strongly marked on the inner, so that the terminal portion of the hydrotheca has the aspect of being recurved towards the hydro- can lus, an appearance which is strengthened by the outer marginal tooth being longer than the other two. The hydrothecse in this variety are proportionately longer than in the others. Both series are strongly directed forwards, and when the pinnate form is fully developed the hydrophyton bears a remarkable similarity to that of S. neglecta, from which species it may be distinguished by the pinnae being mostly alternate instead of sub-alternate, and being given off below each hydrotheca on the pinnate part of the stem instead of below every second one on each side, by the much shorter marginal teeth ot the hydrotheca, and by the internal teeth, also by the different gonangia. While it must be admitted that the arrangement of these varieties under one species is not perfectly satisfactory, they appear to run into each other by so many intermediate forms that I have so far failed to find any distinct line of demarcation between them. It is not improbable that S. indivisa will have to be referred to the same species, and perhaps S. solidula. All the varieties possess teeth within the hydrotheca-margin, one within each of the two upper sides, and either one or three within the lower side. The hydrotheca often has two minute rod-like thickenings of the perisarc about midway down, on opposite sides. SERTULARELLA SOLIDULA, Bale. (Plate XV., figs. 3-4). A specimen from Bondi, with the ends of the hydrothecse curved outwards rather more than those of the type form. SERTULARELLA CYLINDRICA, n.sp. (Plate XVI., fig. 7). Hydrocaulus about half an inch in height, simple or slightly branched, divided by oblique joints into internodes of moderate 766 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, length, each bearing a hydrotheca on its upper part. Hydrothecie adnate nearly half their height, large, stout, cylindrical, smooth, usually somewhat rounded at the base, curved outwards ; aperture looking outwards and upwards, not contracted, margin entire, very slightly everted, peristome often double or triple. Gonothecse unknown. Hob. Port Jackson. A single specimen occurred among a mass of S. divaricata var. sub-dichotoma. It is quite unlike any Australian species hitherto known, and may be readily distinguished by the uncontracted entire margins of the hydrothecse. The latter somewhat resemble those of Sertularia patula. Busk, but are free for a much greater portion of their length. I could not satisfy myself of the exist- ence of an operculum. SYNTHECIUM, Allman. The genus Synthecium differs from Sertularia in the gonosome, the pedicels of the gonarigia having their origin within certain of the hydrothecse, where they take the place of the hydranths. The Sertularia ortkogonia of Busk, the gonosome of which has hitherto been unknown, belongs to this genus, so also doubtless does S. patula. The Dynamena tubulosa, Heller (Zoophyten mid Echinodermen des Adriatischen Meeres), is evidently a Synthe- cium. Professor Allman has remarked that Heller's figure shows a gonangium springing directly from the stem, but I have no doubt that what Heller has figured is a parasitic hydroid like Campan- nularia (?) costata. The five known species all agree in having opposite pinnse, which spring from the stem at a point where there are no hydro- thecse, also in having the hydrothecse opposite, tubular, curved outwards, and with the margin entire. Professor Allman's two species (which are probably reducible to one) have the hydiothecae very much slenderer in proportion to the length than S. ortkogonia and S. patula (which may perhaps be also united). Heller's species is likewise very similar to S. patula, and may be identical. BY W. M. BALE. 767 SYNTHECIUM ORTHOGOXIA, Busk. (Sertularia orttioyonia, Busk, "Voyage of the Rattlesnake.") (Plate XVIL, figs. 1-5). Hyclrocatilus pinnate, attaining a height of about three inches ;. iaternodes of the stem long, each bearing a pair of pinnae at the summit, and one or two pairs of hydro thecse below (except the lower internodes, which commonly bear a pair of pinnae only) ; pinnae distant, opposite, widely diverge nt, divided into internodes, each with one pair of hydrothecae. Hydrotheca* opposite, not in contact but often approximate in front, tubular, adnate most of their height, free part curved outwards more or less abruptly and often produced horizontally ; aperture circular, vertical or directed slightly upwards, margin entire, very slightly everted, usually more or less marked with lines of growth. Gonothecse large, elongated, somewhat compressed in a plane vertical to that of the hydrocaulus, with about 8-10 distinct trans- verse undulations on the broader sides ; aperture terminal, very small, without thickened border or distinct operculum. Hab.Off Ball's Head, Port Jackson. 1 have no doubt that this is the Sertularia orthogonia of Busk, though the free part of the hydrothecse is rarely produced outward to so great an extent as in the type form. This abbreviation of the hydrotheca tends to weaken the distinction between this species and S. patula, nevertheless it is still open to doubt whether they should be united. The hydrothecse of S'. orthogonia are longer than those of 5. patula, and the adnate portion is decidedly more erect, while the free part is curved outwards much more abruptly, and the aperture is nearly or quite vertical, even when the terminal portion of the hydrotheca is somewhat ascending. The margin is not noticeably sinuated at the sides, and is marked with lines of growth even in the terminal hydrothecae. In S. patula the hydrothecse are smaller and are not abruptly flexed, but are gradually curved outwards for most of their length, while 768 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, at the same time the free portion is not nearly so divergent as is generally the case with S. orthogonia. The aperture is at right angles to the terminal part of the hydrotheca, and the margin is slightly sinuated at the two sides, while it is more everted than in & orthogonia, and lines of growth seem rare. It is true that in each species calycles may be found which are somewhat inter- mediate, but there is no difficulty in distinguishing between such specimens as I have met with ; I therefore hesitate to unite them without further evidence. The gonothecse are large and compressed, so that in an ordinary view of the polypary they are seen edgewise, the transverse undulations then appearing very distinct. These undulations, however, do not run round the gonotheca, but are confined to the two broader sides, and gradually smoothed away towards the narrower sides, so that if the gonotheca be viewed in its broader aspect its outline appears smooth or nearly so. In Professor Allman's two species the undulations are continued till they meet two zig-zag median lines which run down opposite sides of the gonotheca ; the goriothecse also are much shorter than those of S. orthogonia, and apparently not so compressed. One fragment of S. orthogonia, found among the rest, has gonothecae not unlike those of Allman's species in size and shape, and showing chitinous ridges in the front view, which however do not run straight across to meet a mesial line, but form an entirely irregular network. I am not aware of the signification of these peculiar gonangia, so different from the ordinary ones, but they may be due to an accidental deformity. The hydrothecse of &. orthogonia are usually directed outwards, but in some specimens they are also turned towards the front, the opposite hydrothecae being almost in contact in the front of the polypidom. SERTULARIA GBNICULATA, n.sp. (Plate XVIL, figs. 6-11). Hydrocaulus simple, minute, with a pair of hydrothecae on each mternode, joints slender. Hydrothecse opposite, in contact with BY W. M. BALE. 769 ach other in front, separated behind, the outer side of each form- ing a strongly salient angle below the aperture ; the body of the hydrotheca projecting forward from the internode, the distal por- tion twisted upwards; aperture nearly vertical, margin without distinct teeth. Gonothecse rather small, ovate, with 5 or 6 strong transverse costae ; one only on a shoot, springing from the basal part of the proximal internode. This species, which I found running over the surface of a Flustra, is very small, none of the shoots which I observed bearing more than three pairs of hydrothscje, the peculiar twisted form of which is very distinctive. The most nearly allied species is perhaps the Dynamena confer ta of Kirchenpauer. SERTULARIA COMPLEXA, S. F. Clarke. (Plate XVIIL, figs. 1-4). Hydrorhiza stout, shoots simple, about half an inch in height, with a pair of hydrothecse on each internode. Hydrothecae opposite, in contact with each other in front, separated behind, long, tubular, free for about J of their length, upper portion curved outward, the hydrotheca-wall produced downwards into two points below the inner side of the base ; aperture vertical, margin with two lateral teeth or angular lobes, Gonothecse borne principally on the hydrorhiza, small, sub- globular, truncate at the summit, with 6-8 distinct annulations ; aperture operculate, margin not elevated, a few small irregular teeth within the margin. Hab. Boncii Bay : Yucatan, America (Clarke). This slender species, which is found profusely over-running leaves of Zostera or Cymodocea, very nearly resembles S. tuba in the form of its hydrothecse, but differs from that species in its simple habit and in the form of the gonothecse. The two spines which in S. complexa project downwards from the base of the hydrotheca into the cavity of the hydrocaulus are also distinctive, but are 770 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, often wanting in some of the calyeles. There is a conspicuous oblique joint at the base of the lowest internode of each shoot. Mr. Clarke's figure and description* agree with our specimens, except that he represents the teeth of the hydrotheca-margin for the most part above and below the aperture rather than at the sides ; but one or two of his figures approximate to the present form in this respect, and the other details being precisely similar, 1 have little doubt that the identification is correct. The gono- thecse were not present in Mr. Clarke's specimens. SERTULARIA ELONGATA, Lamx. Coogee. A small specimen with some of the cauline intei nodes bearing only a pair of hydrothecse and no pinnae. PASYTUEA QUADRIDENTATA, Ellis and Solander. (Plate XIV., figs. 6-7). Coogee ; Bondi. Of these specimens, that from Coogee most resembles the type, but is distinguished by the internodes being less elongated, so that the sets of hydrothecse are close together. The Bondi specimens are peculiar, a considerable proportion of the internodes bearing only a single pair of calyeles each ; indeed some of the shoots are so arranged throughout, and thus differ in no respect from a typical Sertxlaria. The apertures of the calyeles are directed more to the front than in the type, and have blunter teeth, and the hydrothecae generally, when not united in sets, strongly resemble those of some forms of S. australis and S. loculosa; and as in the latter species the joints between the internodes are in some cases simple and inconspicuous, while in others the upper internode is produced downwards to a point, and the lower is similarly produced upward behind it. I observed a single gonotheca, which was sub-globular, with about four not very prominent transverse annulations, and a large aperture with an elevated neck and an operculum. * Report on the Hydroida collected during the exploration of the Gulf Stream and Gulf of Mexico, by Alexander Agassiz 1877-78. (Bull. Mus. Comp. Zool., Cambridge U.S., Vol. V No. 10) BY W. M. BALE. 771 PASYTHEA HEXODON, Busk. Plate XIV., figs. 8-9. Hydrocaulus 1-2 inches in height, sub-dichotomously branched, with a hydrotheca in each axil ; internodes tubular, long and slender, bearing the sets of hydrothecae near their upper extremi- ties, joints mostly inconspicuous. Hydrothecee tubular, usually from six to ten in a set, often unequally arranged on the two sides of the internode, each one adnate to that next above it by a considerable part of its dorsal surface, and adnate to the hydro- caulus by its basal portion ; the two series strongly divergent, the lower ones of a set more so than the upper, especially in their terminal portions ; an angular ridge running down each side of the cell ; aperture very oblique (sloped off from below), margin somewhat expanding at the upper part of each side, with two indistinct lateral lobes. Hob. Near Peel Island, Moreton Bay (Mr. J. D. Ogilby). This species has not hitherto been recorded since Mr. Busk described it in the account of the " Voyage of the Rattlesnake." Mr. Busk says that there are six hydrothecae in a set, but in these specimens there are commonly eight to ten, and sometimes more. While P. quadridentata is closely allied to the Sertulariae, having its calycles in distinct pairs, with the two calycles of each pair in contact in front, P. hexodon, on the other hand, approximates to the Thuiarise, the hydrothecae being crowded and overlapping each other, as is so often the case in that genus, while there is no regularity in the arrangement of the two series with regard to each other. In. most cases those on the two sides of the hydro- caulus are opposite to each other, but it is quite common to find them alternate, and the set frequently contains more on one side than the other, as three to four, or four to six. The ramification is not perfectly dichotomotis, but branches are given off irregu- larly in the same plane, the axial hydrothecee being adnate for most of their length to the principal shoot. 50 772 SOME NEW AND FARE HYDROIDA IN THE AUSTRALIAN MUSEUM, THUIARIA SINUOSA, n.sp. (Plate XVIII., figs. 9-10). Hydrocaulus pinnate, stem indistinctly and irregularly jointed, fascicled below ; pinnae alternate, with few or no joints, three hydrothecse between every two on the same side of the stem. HydrothecsB opposite to alternate on the pinnse, alternate on the stem, a rather wide space between the two series ; long, sub- conical , each one curved first slightly outwards and then upwards, the extreme summit again curved outwards, adnate in their lower half to the hydrocaulus, and in their upper half to the next hydrotheca above, which they overlap ; a conspicuous triangular area below the base of each ; aperture small, semi-circular, looking directly outwards. Gonothecae borne in rows along the front of the pinnae, obovate, with distinct transverse annulations, aperture large, margin elevated : a few long crooked teeth or spines inside the neck. Hab.Port Molle. I received a small piece taken from a specimen in the Museum, which, Mr. Whitelegge informs me, is about two inches high, and incomplete. The species is allied in some respects to T. fenestrata, but the peculiar form and arrangement of the calycles distinguish it from all other known species. The stem has few joints and those indistinct ; the shortest internode has two hydrotheca on the same side as the pinna (which springs from between them and is in contact with both), and a single one on the opposite side. The longer internodes are equivalent to two or more of these with the joints obliterated. The shorter pinnae in my specimen were with- out joints, the longer ones had a single joint not far from the end. There is a thinning away of the perisarc over the triangular spaces below the hydrothecse, very much as in T. fenestrata. THUIARIA QUADRIDENS, Bale. A slender variety, from near Peel Island, Moreton Bay. BY W. M. BALE. 773 THUIARIA FENESTRATA, Bale. Moreton Bay, Queensland ; Port Phillip Heads, Victoria. This species must be added to the list of those which occur on both the southern and north-eastern coasts, as I have received from Dr. MacGillivray a fine specimen obtained at Port Phillip Heads. The shoots are very numerous, and form a densely matted tuft ; the two series of calycles are rather closer together than in other specimens which I have seen. Gonothecse were present, and differ from the figure and description given in the " Catalogue," the border being plain. In representing the gonotheca as having four emarginations of the border, I followed a drawing of Mr. Busk's taken from a hydroid in the Gay herbarium, labelled Solatia tetracyUarcij'&nd identical with his Sertularia crisioides (T. Jenestrata). The present specimens however, exhibit no trace of any toothed or emarginate state of the border. PLUMULAEIID^E. ELEUTHEPvOPLEA. AZYGOPLON, n.gen. Hydrophyton pinnate, supracalycine sarcothecae absent, mesial anterior sarcotheca not adnate to the hydrotheca, nor in contact with it. Gonosome without phylactocarpal appendages. This genus (of somewhat doubtful position) is proposed for the reception opthe species which I originally described under the name of Plumularia producta, and is characterised mainly by the absence of supracalycine sarcothecse, a feature which it exhibits in common with the genera Halicornopsis (Azygoplon, Allman) and Diplocheilus. The latter genus, however, is said to be dis- tinguished by the presence of an external calycine envelope, and the former has the anterior sarcothecee adnate to the front of the hydrothecse, as in other Statoplea; while in Azvgoplon the 774 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, anterior sarcothecse are quite disconnected from the hydrotheca?, and bear a considerable resemblance to the corresponding organs in some of the Eleutheroplea. To that section, therefore, I would assign the new genus, more especially as the only Plumularian which is known to share with A. productum the peculiarity of possessing decumbent adnate gonothecse (namely, Plumularia filicaulis] is an undoubted Eleutheroplean. The generic name Azygoplon has already been applied by Professor All man to another hydroid, for which, however, the name Halicornopsis had priority. AZYGOPLON PRODUCTUM ( = Plumularia producta, Bale). (Plate XIX., figs. 1-5). From an examination of specimens obtained by Mr. Whitelegge at Coogee, I am able to give a more complete account of this species than has hitherto been possible, the gonangia in particular, not having been previously observed. These are given off from the hydrorhiza, and are attached to the supporting substance by the flat under side, like those of Plumularia filicaulis and the whole hydrosoma of Lineolaria. The upper side is convex, and furnished with transverse undulations, which vary in distinctness, but do not appear to be ever very strongly marked ; they are usually indistinguishable when seen from above in a fluid medium, but are readily seen by reflected light when dry. The gonotheca^ are large in size, of an irregularly ovate outline, and there is at first no trace of an aperture, but after a certain time a rather large circular area of the capsule close to the distal end appears as if bulged in, forming a slight concavity bounded by a circular ridge at which separation ultimately takes place. I have not alluded to the cauline sarcothecae in former descrip- tions of this species, as I failed to see them satisfactorily in my first specimens, owing to their rudimentary condition and the wrinkling of the delicate perisarc ; but I have been able to make them out in other cases, and particularly in Mr. Whitelegge's specimens. There are usually two at the base of each pinna, one BY W. M. BALE. 775 of which, situated in the axil, is larger than the other, and both are simply conical projections. In a specimen from Queenscliff the axillary sarcothecse have a distinct incomplete partition just within the aperture, but this bithalamic condition is absent from the others. In several specimens I could only distinguish the axial sarcothecte. Besides the sarcothecse already mentioned there is sometimes one at the summit of each stem-internode in front. The mesial anterior sarcothecse consist, in their perfect form, of a lower chamber, or protuberance of the pinna, terminating in a shallow concave or saucer-shaped receptacle facing the hydrotheca, and emarginate below, where the rim terminates at each side by becoming united to the pinna. In Mr. Whitelegge's specimens however, the wall of the upper loculus is usually cut away on both sides so that there remains only a scoop-shaped projection directed towards the hydrotheca from the top of the lower chamber, and presenting, when seen in front view, a more or less rectangular form. Some of the sarcothecae however approximate to the ordinary form, while different varieties of the species present various intermediate forms between the extremes above-mentioned. There is a striking resemblance between this species and the DiplocJwilus mirabilis of Professor Allman's " Challenger " Report, so far as the more important structural features are concerned. Both species agree in the absence of the supraca- lycine nematophores, and in having the anterior nematophore unattached to the calycle, and even the peculiar form of the nematophores appears almost alike in both species, except that those of A. productum are more erect. The only distinction of more than specific value is the presence in D. mirabilis of an external envelope surrounding the upper part of the hydrotheca, and from analogy with several other species it seems extremely probable that the external envelope is really the outer surface of a thickening of the calycle, and not a distinct structure. Such thickenings of the perisarc are by no means rare, familiar examples being the stem-internodes of Obelia yeniculata and the calycle- wall of Campanularia caliculata, while in Eucopella we have an extreme case, the hydrotheca being almost entirely filled by a 776 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, solid mass of chitinous substance. Sometimes this substance is marked by striae indicating variations of density, and proving its solidity ; but in some cases, as in 0. caliculata, it is homogeneous, so that the hydrotheca resembles an inner cup with an outer calycine envelope, the illusion being, as Mr. Hincks says, so complete that he at first described this as the actual structure. The hydrothecae of Plumularia delicatuta are considerably thickened internally at the same part where in D. mirabilis the calycine envelope is said to exist, and specimens of P. setaceoides in the present collection have an external thickening in front still more extensive. A. productum itself is frequently thickened in the same fashion, if not to the same extent. That this should be the case with some specimens and not with others is quite conformable to experience ; for example, in some forms of C. caliculata there is no noticeable thickening of the calycle, and Dr. von Lendenfeld finds a similar variation in Eucopella. When the chitinous mass is homogeneous in appearance it appears to be very incompletely solidified, so that drying it, or immersing it in a dense medium, such as Canada balsam, causes it immediately to shrink. While it would be impossible to decide absolutely, without examination, that the structure of D. mirabilis is as I have suggested, the analogy of the other species mentioned is so strong as to render such a conclusion highly probable, in which case D. mirabilis and A. productum would be clearly referable to the same genus. As regards specific characters, A. productum differs from D. mirabilis in its much smaller size, in the form of the hydrotheca, in the presence of a distinct anterior intrathecal ridge, and in some minor features. PLUMULARIA CAMPANULA, Busk. ( = P. laxa, All man ; P. Torresia, von Lendenfeld). (Plate XX., figs. 1-6). The specimens from the Museum, as well as some from Port Phillip Heads, sent me by Mr. J. B. Wilson, include the gonothecse, which I have hitherto been able to describe very imperfectly, BY W. M. BALE. 777 owing to my former specimens having been all dried, and more or less shrivelled. The female capsules are nearly three times the length of the hydrothecse, pear-shaped, slightly flattened above, and tapering off gradually below, and are provided with a pair of sarcothecae near the base, one on each side. When ripe they open at the summit by a circular operculum, the border of the orifice being very slightly thickened. Between the short pedicle and the capsule itself there is a distinct sub-globular segment. In some specimens the capsules are broader towards the summit than in others. The male gonothecse are considerably smaller, ovate, not flattened at the summit, and have only a single sarcotheca. Male and female gonothecse are borne on the same colony. Many of the pinnae of P. campanula bear secondary hydro- cladia, but the character is not constant. A single pinna may bear two or three of these offshoots arranged alternately, and occasionally tertiary hydrocladia are produced. The hydrothecal internodes vary considerably in length in different specimens, or even in the same colony, the hydrothecse varying accordingly in their distance apart, so that the superior median sarcotheca, which is normally placed some distance above the hydrotheca, may be situated almost behind the free margin. P. campanula differs from all other species known to me (except P. rubra) in the short stout lateral sarcothecse, which, moreover, are not freely moveable. The type specimens prove that P. Torresia is identical with P. campanula. Dr. von Lendenfeld represents the calycle-margin as somewhat incurved, and with a double tooth at the back, but as there is no trace of these peculiarities in his types, they are probably due to distortion in mounting. Dr. von Lendenfeld's specimens, from Torres Straits, agree precisely with those collected by Mr. Wilson at Port Phillip Heads; others from Broughton Islands have the female gonotheca somewhat narrower. 778 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, PLUMULARIA RUBRA, von Lendenfeld. (Plate XX., figs. 1-6). Hydrocaulus about three inches high, stems clustered, raonosi- phonic, unbranched, bearing hydrothecae as well as pinnae. Pinnae alternate, distant, one on each internode, often supporting secondary hydrocladia, joints oblique, a hydrotheca on each inter- node, except the first on each pinna. Hydrothecsa borne at the lower ends of the internodes, set at an angle of about 40, large, campanulate, margin entire, free at the back. Sarcothecae bithalamic, canaliculate, fixed and stout at the base ; one at each side of the hydrotheca, pedunculate, one in front, one (or on the stem two) midway between every two hydrothecae, on the same internode as the lower, and one on the proximal internode of each pinna. Gonothecse female, large, pear-shaped, somewhat flattened above, tapering below, with a distinct sub-globular segment at the base of the capsule, and a sarcotheca at each side a little above the base ; a circular operculum at the summit, the border of the aperture slightly thickened : male, small, with one sarco- theca only ; both sexes on the same shoot. Hob. Port Jackson. The minute structure of this species is identical in every particular with that of P. campanula, both as regards the tropho- some and the gonosoine ; but in P. campanula the pinnate branches are borne by a polysiphoiiic stem, while in P. rubra the pinnate shoots spring directly from the hydrorhiza. A stem of P. rubra therefore corresponds to a branch of P. campanula, except that it is usually larger. PLUMULARIA SETACEA, Ellis. P. tripartita, von Lendenfeld. (Plate XX., figs. 14-18). Hydrocaulus about 1J inches in height, monosiphonic, some- times branched, pinnae alternate, not close, one borne near the BY W. M. BALE. 779 summit of each inter-node, divided into alternate long and short internodes, of which only the former bear hydrothecse. Hydro- thecse small, cup-shaped, much expanded upwards, adnate up to the margin, aperture nearly at right angles with the pinna. Sarcothecae bithalamic, canaliculate, slender at the base and moveable ; one below each hydrotheca and one at each side above it, one between every two hydrothecae, on the intermediate inter- node, one at the base of each pinna, and one on the lower part of each stem-internode. Gonothecae borne in the axils, rather slender, fusiform, with a tubular neck directed to one side. Hab. Timaru, N.Z. (Dr. von Lendenfeld) ; Port Phillip Heads (Mr. J. B. Wilson). The specimens of P. tripartite, (which are among Dr. von LendenfekTs types) do not possess any features by which they might be distinguished from P. setacea, the tripartite form of the hydranth being only an occasional feature. The hydrophyton is normally unbranched, but some of the shoots bear several lateral branches, which are very peculiar in their origin, since they commence as ordinary pinnae or hydrocladia, and only become modified into branches beyond the first internode, which bears a hydrotheca and nematophores in the usual way. Mr. Hincks mentions a branched variety of P. setacea as occurring in Britain, but does not state whether the branches are modified from hydro- cladia as in the present case. Plumularia Wattsii has hydrocladia with the hydrothecse and sarcothecae similar in form and arrangement to those of the present species, but the pinnate shoots, instead of springing directly from the hydrorhiza, are borne on a long slender jointed stem. PLUMULARIA TURGIDA, n.sp. (Plate XX., figs. 12-13). Hydrocaulus 1J-2 inches in height, monosiphonic, sometimes branched ; pinnaa alternate, not close, one borne near the summit of each intemode, divided into alternate long and short internodes, 780 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, of which only the former bear hydrothecae. Hydrothecse cup- shaped, slightly expanded upwards, adnate up to the margin, aperture at right angles with the pinna. Sarcothecse bithalamic, canaliculate, slender at the base and moveable, one below each hydrotheca and one on each side above it, one between every two hydrothecse, on the intermediate internode, two at the base of each pinna (one in front of the axil and one behind), and one on the lower part of each stem-internode. Gonosome unknown. Hab. Lyttleton, N,Z. (von Lendenfeld). This species is very closely allied to P. setacea in most respects, including the peculiar mode of branching, but is a little paler in colour, with the pinnse more lax and less divergent. The hydro- thecse are proportionately broader at the base and less expanding upwards, while the pinna is more abruptly swollen below the hydrothecse, giving the species a somewhat distinctive aspect. Another characteristic of P. turgida, is the presence of a sarco- theca behind each axil as well as in front. An American Hydroid identified by Clarke* with Plumularia setacea resembles the present species in these particulars, but is very much larger in growth, measuring sometimes as much as 300 mm. PLUMULARIA CALICULATA, n.sp. (Plate XX., figs. 9-10). Hydrocaulus monosiphonic, about J inch high, pinnae alternate, not close, one borne near the summit of each internode, divided into alternate long and short internodes, of which only the former bear hydrothecse. Hydrothecse cup-shaped, shallow, slightly expanding upwards, adnate up to the margin, aperture nearly at right angles with the pinna. Sarcothecae bithalamic, canaliculate, *Hydroids of the Pacific Coast of the United States, south of Vancouver Island, &c., S. F. Clarke. Trans, of the Connecticut Academy of Arts and Sciences, Vol. III., Part 2. BY W. M. BALE. 781 slender at the base and moveable ; one below each hydrotheca, and one at each side above it, one between every two hydrothecae, on the intermediate internode, one at the base of each pinna, and one on the lower part of each stem-internode. Gonothecse small, ovate or oblong, somewhat compressed, slightly narrowed at the summit. Hob. Bondi Bay, Port Jackson. This species differs from P. setacea in its smaller size, and in the gonothecae, which are stouter in proportion, and have no neck. As seen in side view they are nearly oblong, but in front view they are somewhat barrel-shaped. Some of them are rather abruptly narrowed towards the summit, but this is not always the case ; possibly the difference is developmental. The hydrothecae are some- what shallower in proportion to their height than those of P. setacea y and more rounded. In one of the specimens the pinnae are borne in opposite pairs at the summit of each internode, except at the upper part, where the ordinary alternate arrangement recurs. PLUMULARIA SETACEOIDES, Bale. Bondi. < Plate XX " 7 - 8 )' This is a rather small form of P. setaceoides with short pinnae, and, like the small southern variety, has the hydrothecae shallower and more expanding towards the aperture than the long slender form. They are also set at a wider angle on the pinna, and have the front so much thickened as to present the appearance of an outer chitinous investment at this part. The thickened portion shrinks when the zoophyte is preserved in. balsam, and even to some extent when in water. Gonangia are plentiful in these specimens, and agree in their general form with those of the type. The large sporosac is sometimes surrounded at the summit by a circle of highly refractive granules, which, as they are not present in all the gonothecae, would appear to belong only to a particular stage of growth . 782 SOME NEW AND RARE HYDROIDA IN THE AUSTRALIAN MUSEUM, In the absence of the gonosome, the present species may be at once distinguished from P. setacea by the calycles being free for part of their length. PLUMULARIA ALATA, n.sp. (Plate XIX., figs. 6-10). Hydrorhiza with transverse markings along the margin ; hydrocaulus minute, monosiphonic, unbranched, internodes at lower part of stem fusiform, those above more slender, cylindrical ; pinnae alternate, one on each internode of the stem, divided into alternate long and short internodes, of which only the former bear hydrotheca3. Hydrothecse tubular, slightly curved outwards, the base springing from a protuberance of the pinna ; aperture partly terminal, emarginate behind, and partly continued as a narrow sinus nearly half way down the front of the hydrotheca ; the sides of the margin forming two lobes, which are somewhat recurved towards the pinna. Intrathecal ridge anterior, projecting from the front extremity of the aperture j into the cell in a backward and upward direction ; an external narrow projecting web partly crossing the hydrotheca and pinna on each side immediately behind the lateral sarcotheca. Hydrothecal internodes with three transverse folds or constrictions. Sarcothecse bithalamic, canali* culate, slender at the base and moveable ; one immediately below each hydrotheca and two laterals behind it, one between every two hydrothecse, on the intermediate internode, two on each stem-interne de, and a number scattered over the hydrorhiza. Gonosome unknown. Hob.- (?) This is a noteworthy species for several reasons, not the least of which is its small size. Out of all the specimens examined the largest were only inch in height, or less than any other known Plumularian. The form of the hydrotheca, more especially of the aperture, is unlike that of any other species, the aspect presented in a front view being that of a narrow longitudinal opening half BY W. M. BALE. 783 the length of the hydrotheca, terminating below in a slight rounded enlargement, and above in a similar but larger extension at the end of the hydrotheca. The supracalycine sarcothecse are set behind the upper part of the hydrotheca, so that in a front view they can only be seen by focussing down through it. The possession by this species of a distinct intrathecal ridge, anterior in position, is a feature which, though common among the Australian Statoplea, has not hitherto been recorded as occurring in any member of the Eleutheroplean group, except in a single doubtful species, Azygoplon productum; the true Plumulariee which are furnished with an intrathecal ridge, as P. spinulosa, P. j'ticaulis,