ANATIFA SULCATA. _Quoy et Gaimard._ Voyage de l"Astrolabe, Pl.
xciii, figs. 18, 20.[28]
[28] I may add, that I have received many specimens incorrectly labelled _A. striata_, which is properly a synonym of _L.
anserifera_.
_L. valvis tenuibus, cra.s.se sulcatis, saepe pectinatis; scutorum crista prominente ab umbone ad apicem juxta marginem occludentem pertinente: furcae carinalis cruribus inter angulos 135 et 180 divergentibus._
Valves thin, coa.r.s.ely furrowed, often pectinated. Scuta with a prominent ridge extending, from the umbo to the apex, close to the occludent margin; fork of the carina with the p.r.o.ngs diverging at an angle of from 135 to 180.
Filaments absent, or only one on each side.
Var. (Pl. I, fig. 3 _a_), upper part of the terga (bounded by the two occludent margins) produced and sharp; surface of all the valves often coa.r.s.ely pectinated, and with the carina barbed.
Atlantic Ocean, from the North of Ireland to off Cape Horn; common, under the tropics; Mediterranean: attached to wood, cork, charcoal, sea-weed, a reed-like leaf, spirulae, cuttle-fish bones, to a bottle together with _L. anatifera_; to a ship"s bottom, Belfast, (W. Thompson.) Often a.s.sociated with _L.
fascicularis_. Montagu states ("Test. Brit.," p. 18) that this species is sometimes attached to the fixed _Gorgonia flabellum_.
_General Appearance._--The capitulum varies considerably in length compared to its breadth, caused chiefly by the greater or less production of the occludent portion of the terga; valves thin, brittle; the furrowed surface varies much in character, narrow and broad ridges often alternating; frequently each ridge (but more especially the ridge running from the umbo to the apex of each scutum, and sometimes that alone,) is covered with prominent, curled, flat, calcareous spines, giving the sh.e.l.l an appearance like that of many mollusca. Other specimens show no trace of these calcified projections. From the thinness of the valves and the depth of the furrows, the margins of the valves are sinuous. _Scuta:_ the ridge running from the umbo to the apex is unusually prominent and curved; it runs very close to the occludent margin, so that, differently from in all the other species, only a very narrow s.p.a.ce is left between this margin and the ridge. Internal teeth, under the umbones, either sharp and prominent, or mere k.n.o.bs; sometimes that on the right side is much larger than that on the left; sometimes they are nearly equal; sometimes that on the left is scarcely distinguishable. Internal basal rim absent, or barely developed.
_Terga:_ these valves have a conspicuous notch to receive the apex of the scuta; the two occludent margins either meet each other at a rectangle, or at a much smaller angle, causing the portion thus bounded to vary much in outline, area, and degree of prominence. This at first led me to think that the _P. spirulae_ of Leach, in which the point is very sharp and prominent, was a distinct species; but there are so many intermediate forms, that the idea must be given up. I may remark, that in all the species of Lepas, the upper part of the tergum seems particularly variable. The degree of ac.u.mination of the basal portion of the tergum also varies; the internal surface sometimes has small crests radiating from the umbo.
_Carina_, broad, within deeply concave; edges sinuous, externally sometimes strongly barbed; narrow above the fork, which latter is wider than the widest upper part of the valve; p.r.o.ngs sharp, thin, diverging at an angle of from 135 to 180; the rim connecting the p.r.o.ngs not, or only slightly, reflexed.
_Peduncle_, narrow, shorter than the capitulum.
_Filamentary Appendages_, none, or only one, short, obtuse projection on each side, on the posterior face of the swelling under the first cirrus.
_Mouth._--Mandibles, with the inferior point produced into a single pectinated tooth, rarely into two pectinated teeth; on one side of one specimen, there were only four instead of five teeth. Palpi very narrow.
Maxillae highly variable; they may be described as formed of five steps, of which the two lower ones are generally united into a single one, divided by a mere trace of a notch; or with the three lower steps blended into an irregular, projecting surface, and with even the fourth step indistinct. I have seen these two extreme forms on opposite sides of the mouth of the same individual,--on one side the maxillae being regularly step-form, on the other the whole inferior part forming an almost straight edge, standing high up above the first notch or step which bears the two upper great spines.
_Cirri._--First pair rather far removed from the second pair, with the longer ramus about three-fourths of the length of shorter ramus of second cirrus; spine-bearing surfaces, hardly at all protuberant; lateral marginal spines on the posterior cirri rather long; caudal appendages smooth, rounded, extremely minute: p.e.n.i.s very spinose.
_Size._--Capitulum in the largest specimen, six-tenths of an inch long; only a few arrive at this size.
_Colours_, after having been kept in spirits,--sack and cirri, especially first cirrus, clouded with pale purple; peduncle brownish; valves appear blueish in specimens not long preserved, but in specimens kept longer they become perfectly and delicately white.
_General Remarks._--Under the head of _L. anserifera_, I have made some remarks on the diagnostic characters of this species. In the thinness of the valves,--form of the carina, with the rim connecting the p.r.o.ngs being not, or scarcely, reflexed,--and in the shortness and narrowness of the peduncle, there is some approach to _L. australis_, and thence to _L. fascicularis_. In the form of the maxillae,--in one specimen having the mandible on one side bearing only four teeth,--and in the frequent absence of filamentary appendages, there is some approach to the genus _Paecilasma_; but there is no such approach in the characters derived from the capitulum. We have seen that, as in so many other species of this genus, most of the parts are variable, and this is the case to a most unusual extent in the form of the maxillae. Dr. Leach has attached eight specific names to the specimens preserved in the British Museum.
5. LEPAS AUSTRALIS. Pl. I, fig. 5.
_L. valvis glabris, tenuibus, fragilibus; scutorum dentibus umbonalibus utrinque internis; carinae parte superiore lata, plana, supra furcam valde constricta; furcae cruribus latis, planis, tenuibus, ac.u.minatis, intermedio margine non relexo._
Valves smooth, thin, brittle; scuta with internal umbonal teeth on both sides. Carina with the upper part broad, flat; much constricted above the fork, which has wide, flat, thin, pointed p.r.o.ngs, with the intermediate rim not reflexed.
Filaments, two on each side.
Common on Laminariae in the whole Antarctic Ocean: Ba.s.s"s Straits, Van Diemen"s Land: Bay of Islands, New Zealand, lat.
35 S.: lat. 50 S., 172 W.: coast of Patagonia, lat. 45 S.: attached to bottom of H. M. S. Beagle, lat. 50 S., Patagonia: attached to a Nullipora, (I presume a drift piece,) British Museum.
_General Appearance._--Capitulum rather obtuse and thick; valves thin, brittle, approximate, either white and transparent, or dirty-brown and opaque; or sometimes tinted internally with purple (perhaps the effects of being preserved in spirits); surface plainly marked by lines of growth, rarely marked with traces of lines radiating from the umbones.
_Scuta_ with teeth on both sides, nearly equal; internal basal rim rather wide, sometimes furrowed; basal margin considerably curved inwards. _Terga_ rather wide; basal angle blunt; angle formed by the two occludent margins blunt and rounded. _Carina_ (fig. 5 _a_) with the apex blunt, flat; the middle part generally very broad; much constricted above the fork, where it is internally deeply concave, and externally carinated; fork twice as broad as the broadest upper part of the valve; with the p.r.o.ngs flat, broad, thin, pointed, diverging at about an angle of 75, with the intermediate rim not at all reflexed; the fork generally not deeply imbedded in the chitine membrane of the peduncle, so as to be quite easily visible externally; sometimes there is an internal, transverse, depressed line on the fork. In young specimens, with the capitulum about a quarter of an inch long, the fork of the carina is not developed, the lower slightly inflected portion consisting simply of an oval plate, twice as wide as the upper part. Until I had carefully examined a perfect series, showing the gradual changes in this part, I did not doubt that the young specimens formed a distinct species, and named it accordingly: the shortness of the p.e.n.i.s first made me perceive that the specimens were immature. At this early age, I may add, the filamentary appendages were not developed. _Peduncle_ either quite short, or as long as the capitulum, close under which it is considerably constricted all round.
_Filamentary Appendages._--Two on each side; one long, tapering, placed on the prosoma (in one specimen represented by a mere k.n.o.b), and the second shorter, situated on the posterior margin of the swelling beneath the first cirrus.
_Mouth._--Maxillae, with three large spines at the upper angle, and with the first step distinct, but narrow; mandibles with five teeth; in young specimens the inferior point ends in a single spine; sides of the supra-oral cavity very hairy; the membrane, forming the inner fold of the labrum, yellow and thickened in the form of a spoon.
_Cirri._--In the posterior cirri there are, at the upper lateral edges of the segments on _both_ sides, small spines; the segments in the first cirrus, and in the broad anterior ramus of the second cirrus, are hemispherically and considerably protuberant. Caudal appendages smooth.
_Size._--The largest specimen had a capitulum one inch long.
The _Colours_ (after having been long in spirit) of the valves have already been given; sack and peduncle dirty yellowish-brown, with the parts corresponding to the margins of the valves much darker brown, or almost black; segments of the cirri clouded with dark brown; body and pedicels of the cirri dirty yellowish. I have reason to believe that the colours are totally different in living specimens.
_Monstrous Varieties._--Most of the specimens from lat. 50 S., on the coast of Patagonia, were more or less deformed, with the successive zones of growth overlapping each other, and forming coa.r.s.e concentric ridges. The carina in several specimens was laterally distorted.
I have already remarked that this species has some affinity to _L.
pectinata_; but it is much more closely related to _L. fascicularis_, the affinity being clearly shown by the thinness and translucency of the valves, their convexity, by the width and little ac.u.mination of the upper part of the carina, by the width of the fork, and by its not being deeply imbedded. In young specimens, moreover, before the fork is fully developed, there is a remarkable similarity between the two species, in the form of this lower part of the carina. Again, the narrowness and inflection of the peduncle under the capitulum in _L. australis_, and lastly, the lateral marginal spines on both sides of the segments of the posterior cirri, all clearly indicate this same affinity to _L.
fascicularis_.
I believe this species is confined to the southern ocean; and perhaps there represents _L. fascicularis_ of the northern and tropical seas. It must, judging from the number of specimens brought home by Captain Sir J. Ross, and from those previously in the British Museum, and from those collected by myself, be a very common species.
6. LEPAS FASCICULARIS. Pl. I, fig. 6.
LEPAS FASCICULARIS. _Ellis_ and _Solander_. Zoophytes, 1786, Tab.
xv, fig. 5.
---- ---- _Montagu._ Test. Brit. Suppl., 1808, pp. 5, 164.
---- CYGNEA. _Spengler._ Skrifter Naturhist. Selbskabet, Bd. i, 1790, Tab. vi, fig. 8.
---- DILATA. _Donovan._ British Sh.e.l.ls, 1804.
PENTALASMIS FASCICULARIS. _Brown._ Ill.u.s.t. Conch., 1844, Pl. li, fig. 2.
---- SPIRULICOLA (!) et DONOVANI (!) _Leach._ Tuckey"s Congo Expedit., p. 413, 1818.
ANATIFA VITREA. _Lamarck._ Animaux sans Vertebres.
DOSIMA FASCICULARIS. (!) _J. E. Gray._ Annals of Philosophy, vol.
x, 1825.
PENTALEPAS VITREA. _Lesson._ Voyage de la Coquille. Mollusca, Pl.
xvi, fig. 7, 1830.
ANATIFA OCEANICA (!) _Quoy_ et _Gaimard_. Voyage de l"Astrolabe, Pl. xciii.
_L. valvis glabris, tenuibus, pellucidis; carina rectangule flexa, parte inferiore in disc.u.m planum oblongum expansa._
Valves smooth, thin, transparent; carina rectangularly bent, with the lower part expanded into a flat oblong disc.