Pamina. J. E. Gray. Annals of Philosophy, vol. x, (Second Series,) August, 1825.[35]
[34] The general title to the volume, containing four Quarterly parts, is dated 1818; but as in the ‘Journal de Physique,’ for July, 1817, the editor refers to Conchoderma, the Quarterly Part containing this genus must have appeared before 1818: Lamarck gives the year 1814 as the date of the paper in question, and I have accordingly followed him. From a similar reference by the editor, it appears that Schumacher’s volume appeared before the number of the ‘Journal de Physique’ containing Leach’s Paper.
[35] Under these nine generic names, the two common species of Conchoderma have received thirty-three different specific denominations, caused partly by changes of nomenclature, and partly from varieties having ranked as species.
Valvæ 2 ad 5, minutæ, inter se remotæ: scuta bi-aut tri-lobata, umbonibus in medio marginis occludentis positis: carina arcuata, terminis utrinque pæne similibus.
Valves 2 to 5, minute, remote from each other: scuta with two or three lobes, with their umbones in the middle of the occludent margin: carina arched, upper and lower ends nearly alike.
Filaments seated beneath the basal articulations of the first pair of cirri, and on the pedicels of four or five anterior pairs; mandibles, with five teeth, finely pectinated; maxillæ step-formed; caudal appendages, none.
Distribution.—Mundane, throughout the equatorial, temperate, and cold seas; attached to floating objects, living or inorganic.
The Capitulum is formed of smooth membrane, including five small valves, of which the terga and carina are often quite rudimentary or absent. Valves minute, thin, generally more or less linear, placed far distant from each other; sometimes imperfectly calcified and covered by chitine membrane, or imbedded in it. The umbones of the valves (together with the primordial valves) are nearly central, so that they are added to at their upper and lower ends; hence their manner of growth is considerably different from that of the valves in Lepas. The adductor muscle is attached to a slight concavity on the under side of each scutum, at the point whence the lobes diverge.
The Terga are placed almost transversely to the scuta; at their lower ends, there is either a very slight prominence in the capitulum, or there is a large tubular, folded appendage, opening into the sack, and apparently serving for respiratory purposes.
Peduncle, smooth, moderately long; attachment effected by the cement-stuff being poured out exclusively, as it appears, from the larval antennæ. These antennæ in C. aurita and C. virgata, resemble, in the form of the disc and in the long feathered spines on the ultimate segment, those in Lepas.