Pollicipes cornucopia. Leach. Encyclop. Brit. Supp., vol. iii, 1824.
—— —— — Smythii, var. Leach. Ibid.
Lepas Pollicipes. Gmelin. Systema Naturæ, 1789.
—— —— — gallorum. Spengler. Skrivter Naturhist. Selskabet, Bd. i, Tab. vi, fig. 9, 1790.
P. capitulo, valvarum duobus aut pluribus sub-rostro verticillis instructo: valvis albis, aut glaucis: pedunculo, squamarum densis verticillis symmetricè dispositis.
Capitulum with two or more whorls of valves under the rostrum; valves white or gray; scales on the peduncle symmetrically arranged in close whorls.
Maxillæ with three tufts of fine bristles, separated by larger spines: segments in the first cirrus less than half the number of those in the sixth cirrus: caudal appendages multi-articulate: filamentary appendages attached to the prosoma.
Coast of Portugal; mouth of the Tagus. England, Ireland, and the Frith of Forth in Scotland. Mediterranean (according to Brugière): Teneriffe: Mogador, Africa.
This species is said by Montagu (‘Test. Brit. Supplement’) to have been found attached to drift timber in the Frith of Forth, and to the bottom of a wrecked vessel towed into Dartmouth. According to Mr. W. Thompson (‘Annals of Nat. Hist.’ vol. xiii, ), it has been found attached to wood-work near Dublin.
Capitulum, obtusely triangular, massive: valves close together, rather thick, with their exterior surfaces convex, naked, except in the lower parts, where united together by tough, greenish-brown membrane, destitute of spines. The edges of the orifice are widely bordered by membrane, coloured fine crimson red. The valves, in a specimen with a capitulum above three quarters of an inch long, were 52 in number; in a specimen one fifth of an inch long, only between 20 and 30. Two whorls of valves are distinct beneath the carina and rostrum. In one specimen in Mr. Cuming’s collection, with a capitulum 1.4 of an inch long, there were three whorls beneath the rostrum, and four beneath the carina. The scuta, terga, and carina are much larger than the other valves.
Scuta, oval, the basal and tergo-lateral margins sweeping into each other, and the apex pointed; internally (Pl. VII, fig. 1 a) the pit for the adductor muscle is deep.
Terga, larger than the scuta, internally (fig. 1 a) slightly concave; carinal margin much curved and protuberant; basal angle blunt; scutal margin either curved with the upper part straight, or formed of two almost distinct lines, corresponding with the tergal margin of the scutum, and with one of the sides of the upper latus.
Carina, much curved, extending far up between the terga, internally deeply concave, widening much from the top to the bottom; basal margin highly protuberant, with a central portion either truncated and very slightly hollowed out, or bluntly and rectangularly pointed, with the apex itself rounded.
Rostrum, not one third of the length of the carina, concave, triangular, with the basal margin slightly protuberant. Of the other valves, including the sub-carina and sub-rostrum, the shape of their inner surfaces is sub-triangular, with the basal margin convex; externally the umbones are pointed, and slightly curled inwards, so as to overlap each other like tiles: the smaller valves, however, of the lower whorls (fig. 1 a) are more or less transversely elongated, so as to become almost elliptic instead of triangular. Of the latera, the upper pair, which corresponds to the interspace between the scuta and terga, is the largest, but barely exceeds in size the pair answering to the carinal latera in Scalpellum, which lie between the terga and carina: the next largest pair is the rostral, or that between the scuta and rostrum. Some, however, of the lower latera are of nearly equal size.
Peduncle, narrower, but generally longer than the capitulum; upper part encased with small calcareous scales, with their apices curved inwards, and overlapping each other. The inner surface of each scale is triangular, with the basal margin protuberant. The scales continue to grow or be added to, only in about the ten upper whorls, which form but a small part of the whole peduncle; in the lower part, the scales become further and further separated from each other. The surface of attachment, in full-grown specimens, is broad; but in two very young specimens, which I removed with great care after the action of potash, I found the peduncle ending in a filiform prolongation, such as often occurs in Scalpellum vulgare and in Lepas fascicularis. At the extremity of the pointed peduncle, there were seated the larval prehensile antennæ, of which the following measurements are given to show how minute they are.
|
|
Inch. |
|
Length, from apex of disc, to the further edge of the basal articulation |
20/6000 |
|
Breadth of basal segment, in broadest part |
6/6000 |
|
Hoof-like disc, length of |
6/6000 |
|
Ultimate segment, entire length of |
6/6000 |
|
Ultimate segment, breadth, in broadest part |
6/20000 |
The disc resembles a broad, rounded hoof, very little longer than broad, and narrowed in at the heel; the apex is not at all pointed, and bears some minute and thin spines. There is one large spine on the under side of the disc; and another on the basal segment, on the outside, in the usual position. The ultimate segment is long and thin; it has a notch on the inner side (the segment supposed to be stretched forward), bearing two or three long flexuous spines; and there are three or four other spines on the summit: altogether there is a close resemblance with the antennæ in Scalpellum, excepting that the hoof-like disc is not here pointed.
Colours. — Valves internally tinted, in parts, grey; peduncle, brown; corium of sack, purplish-brown, of peduncle, rich coppery brown; cirri, banded dorsally, and with the front surfaces of the segments, purplish-brown. Edge of the orifice of sack, fine crimson red. The specimen here described had been dried for a few weeks, and was then moistened.
Dimensions. — The largest specimen which I have seen, in Mr. Cuming’s collection, had a capitulum 1 and 4/10ths of an inch long; a fine specimen, from Teneriffe, was 9/10ths in length. In a specimen with a capitulum 1/20th of an inch long, and about the same in breadth, there were eighteen valves; so that, besides the principal valves, five pair of latera, the sub-carina, and sub-rostrum, were already developed, and on the upper part of the peduncle, there were many calcareous scales.
Filamentary Appendages. — The prosoma is well-developed, with thirteen or fourteen pair of short, blunt filaments, placed close together in two longitudinal rows; those nearest the thorax are the longest; outside this double row, on each side, there is a row of papillæ, indicating a tendency to the formation of two other rows of filaments. There is a pair of longer filaments, one on each side of the mouth, pointing upwards, and thinly clothed with long spines; at the bases of the first pair of cirri there is a second pair of filaments, shorter and bearing a few minute spines. The bottom of the sack is studded with small rounded papillæ, with roughened summits.
Mouth, not placed very far from the adductor muscle.
Labrum, highly bullate, equalling, in its longitudinal diameter, the rest of the mouth; upper part square, not overhanging the lower part; there are some small teeth on the crest.
Palpi, oval, outer and inner margins nearly alike, thickly clothed with spines.
Mandibles, with three very strong, yellow teeth; inferior point broad, coarsely pectinated. In one specimen, on one side, the third tooth was represented by two smaller teeth.
The Maxillæ bear three conspicuous tufts of fine bristles, separated by larger spines; the first tuft is placed close to the two, upper, large, but unequally-sized spines; the second tuft is placed in the middle, and the third at the inferior angle. The two latter tufts stand on prominences; between the two upper tufts there are three pair, and between the two lower tufts four or more pair of rather strong spines: (see the figure, 13, Pl. X, in the allied P. polymerus.)
Outer Maxillæ, with the inner edge divided in the middle by a conspicuous notch, and with the bristles above and below short, making two equal combs. On the exterior surface, the bristles are longer and more spread out. Olfactory orifices prominent, protected by a punctured swelling between the bases of the first pair of cirri.
Cirri, short and rather thick; the first pair is not far removed from the second. The segments of the three posterior pair are somewhat protuberant, bearing six pair of short, strong spines, graduated in length, between which there is a very thick, longitudinal brush of short, fine, straight bristles, of which the lower ones are the longest; some thick, minute spines arise from the upper lateral edges of the segments. The spines in the dorsal tufts are short, much crowded, and of nearly equal length; see figure, 27, Pl. X, in the allied P. polymerus. In a specimen in which the sixth cirrus had seventeen segments, the first cirrus had, in the shorter ramus, eight segments, of which the lower four were thick and protuberant, with the spines doubly serrated. In this same specimen, the anterior ramus of the second cirrus had twelve segments, of which the five basal ones were highly protuberant, and thickly clothed with non-serrated spines. In the third cirrus the basal segments of the anterior ramus are highly protuberant. The basal segments in the posterior rami of both these cirri, are slightly protuberant, but otherwise resemble the segments in the three posterior pair.
The Caudal Appendages (Pl. X, fig. 22), in full-grown specimens, just exceed in length the lower segments of the pedicels of the sixth cirrus; they are nearly cylindrical, bluntly pointed, with five oblique imperfect articulations; the lower or basal articulations cannot be traced all round, being distinct only on the ventral surface. There is a row of short spines round the upper edge of each segment, with a little, short tuft on the point of the terminal segment. In a rather young specimen, however, with its capitulum one fifth of an inch long, each appendage certainly consisted of a single segment, with spines only on the summit.
Penis purple, with excessively short and fine spines in tufts, chiefly near the extremity. In a specimen with a capitulum only one fifth of an inch long, the penis consisted of a mere pointed papilla, not so long as the caudal appendage, and therefore equalling in length only the lower segment of the pedicel of the sixth cirrus.
Ovigerous fræna. — I could see none, though there were two large lamellæ in the sack. The ova were flesh-coloured, but they had been dried and then placed in spirits. The ova were wonderfully numerous, oval, much elongated, and 1/100th of an inch in length.