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Show 374 MR. W. F. LANCHESTER OX THE [Dec. 2, than the capitulum, white and semi-transparent; in both, however, it is thickly studded with minute chitinous papillae (as in D. warwickii). The 1st cirrus is only | of the length of the 6th, is distant by tbe thickness of its own pedicel from the 2nd, and has its rami equal; the rami also of the other cirri are equal. The caudal appendage is exactly as long as the pedicel of the 6th cirrus, but appears longer to the naked eye owing to the presence, at its tip, of numerous hairs as long as the joint itself. As regards the mouth-parts, the outer maxilla; are ovoid, with their inner sides folded over outwardly and their outer surfaces covered with longish hairs; the inner maxi!he each present an incision on their border by which are formed two low step-like projections, the inner being the smaller, and each bears 13 spines, of which the one at the inner angle is much stouter than the rest. The mandibles have 5 teeth, the strongest of which forms the inner angle. The palpi are bluntly conical, with hairs along their outer edges. The penis is lather thick, and only begins to taper just before its distal end ; along its length are several exceedingly short hairs. This species seems to me to bridge over the narrow gap between the genera Dichelaspis and Pcecilasma, in relation on the one side with the Dichelaspids generally, and on the other side with Pcecilasma tridens Auriv. in particular. My grounds for placing it in the former of the two genera are (a) the connection between the two portions of the scutum, and (b) the extension of the carina between the terga; these two points clearly bring it within Darwin's definition of his genus. At the same time, the bridge of tissue connecting the two parts of the scutum is extremely narrow, so that I was, for some time, for considering the two portions as separate valves and for referring the species to the genus Pcecilasma; while, on the other hand, the carina in Pcecilasma tridens also extends between the terga, though only by ^ of its length. This species, moreover, has a point in common with those of Pcecilasma, and differing from those of Dichelaspis, namely, the close apposition of the valves. But its relationship with both these genera is clearly shown, on the one hand, by the yet present connection between the two parts of the scutum and the extension of the carina between the terga; and, on the other hand, by the almost complete severance of the scutal segments and the close apposition of the valves. And though its possibly closer relationship to one of these genera relieves me of the responsibility of uniting two genera which Darwin separated after the study of a greater number of species, still I feel that there can be little doubt but that the tie between these genera is exceedingly close. There are also some specimens taken from the extreme base of the chelipedes and from the long epipodite of the 3rd maxillipeds of Neptunus gladiator. On the same crab were the specimens of the species next described. |