Alepas minuta. Philippi. Enumeratio Mollusc. Siciliæ, 1836, Tab. xii, fig. 23.
—— —— —— A. Costa. Esercitazione Accadem., vol. ii, part I, Naples, 1840, Pl. iii, fig. 5 (secundum Guerin in Revue Zoolog., 1841, .)
—— —— —— Chenu. Illust. Conch., Pl. iii, figs. 8-10.
A. aperturâ non prominente, capituli longitudinis vix tertiam partem æquante: scutis corneis, pæne absconditis: longitudine totâ ad quartam unciæ partem.
Orifice not protuberant, one third of the length of the capitulum: scuta horny, almost hidden. Total length quarter of an inch.
Outer maxillæ, with the spines in front continuous; posterior cirri, with several long spines arranged in a transverse row on each segment; caudal appendages longer than the pedicels of the sixth cirrus.
Sicily; attached to a Cidaris: island of Capri (A. Costa).
I am greatly indebted to Professor J. Müller, of Berlin, for kindly lending me specimens.
Capitulum oval, blending insensibly into the peduncle; moderately flattened; composed of thin structureless membrane, with the exception of two horny, almost quite hidden scuta. Orifice situated near the summit, and in a line, which is oblique to the longitudinal axis of the peduncle; much wrinkled; barely one third of the length of the whole capitulum.
The Scuta, consist of yellowish, transparent, horny, laminated chitine, without any calcareous matter; externally covered by the common integument of the capitulum; these valves are placed very near to each other, close under the orifice, and therefore high up on the capitulum; the membrane between them is smooth and unwrinkled; they are formed of two rather acuminated lobes, joining each other at above a right angle; one lobe (the longer one) stretching nearly transversely across the capitulum, the other running down parallel to its rostral margin: in shape and position they resemble the scuta of Conchoderma aurita; and if another lobe had been developed it would have run along the orifice, and then these valves would have resembled the scuta of Conchoderma virgata. In a specimen with a capitulum 2/10ths of an inch long, the scuta from point to point were 1/20th of an inch in length.
Peduncle, much wrinkled, about one third in diameter of the capitulum, and shorter than it; at the base it is generally expanded into two or three finger-like projections. Length of the largest specimen, about one fourth of an inch. Colour, according to A. Costa in the work above cited, “rufo-flava vittatâ;” but after spirits the whole becomes uniformly yellowish.
Filamentary Appendages, situated beneath the basal articulation of the first cirrus, on the posterior edge of the usual enlargement; acuminated, about two thirds of the length of the shorter ramus of the first cirrus.
Prosoma well developed.
Mouth. — On each side there are two slight prominences; one under the mandibles, the other transverse nearer to the adductor muscle.
Labrum, placed near the adductor muscle, with the upper part not more bullate than the lower part; crest with a row of blunt teeth, and many fine bristles growing chiefly outside the teeth; there are many fine bristles on the inner or supra-œsophageal fold of the labrum.
Palpi not nearly touching each other, pointing towards the adductor: much hollowed out on their inner sides, hence narrow and acuminated, with doubly serrated bristles.
Mandibles, with three teeth and the inferior angle ending in a single sharp spine; whole inferior portion narrow; first tooth as far from the second, as the latter from the inferior angle; owing to the presence of short thick spines projecting from the sides of the jaw, the lower edges of the second and third teeth appear pectinated.
Maxillæ, nearly two thirds of the width of the mandibles; beneath the three larger upper spines there is a considerable notch, and the whole lower part is very slightly upraised; edge irregular, with obscure traces of either two projections, or perhaps of four steps.
Outer Maxillæ, with bristles in front continuous; exteriorly there is a slight prominence near each olfactory orifice, with a tuft of long bristles.
Cirri not much elongated; first pair placed not quite close to the second; five posterior cirri nearly equal in length; pedicels long, with irregularly scattered spines, — those on the pedicel of the first cirrus beautifully and conspicuously feathered. The segments of the three posterior pair are not very short or broad; very slightly protuberant, each with a long transverse, crescentic, narrow brush of bristles, which stand two or three deep in the middle, but on the sides are single: dorsal tufts long, and in the upper segments the spines are thick and claw-like. This structure is common to all the cirri. First cirrus with the rami unequal in length by two segments; from the shortness of the pedicel, this cirrus is much shorter than the second, but its rami are about two thirds of the length of those of the second cirrus. Second cirrus (and in a less degree the third cirrus), with the anterior ramus a shade broader than the posterior ramus, and rather more thickly covered with spines than are the three posterior cirri. Fifteen segments in the sixth cirrus; nine in the longer ramus of the first cirrus.
Caudal Appendages, rather longer than the pedicels of the sixth cirrus, composed of seven cylindrical, tapering segments, each with a circle of very fine bristles on its summit.
The acoustic (?) sacks are situated some way below the basal articulations of the first cirrus.