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Show 372 MR. W. F. LANCHESTER ON THE [Dec. 2, longish, stiff' hairs, the apex with the usual bundle of short bristles. This species, which Mr. F. F. Lairllaw kindly brought to my notice on an Enhydris which he was examining, is possibly identical with one of which Darwin had only a single young and imperfect specimen, taken off Borneo, from the skin of a sea-snake. It agrees in the presence of the " two or three very distinct ridges on each side of the midrib" internally; but I have been unable to satisfy myself, in these small specimens, of the existence of any pores in the parietes, so that an identification with Darwin's form must remain a matter of doubt. It is clearly marked off from the other two species described by Darwin-(a) from P. bissexlobata by the subequality of the rami of the 1st cirrus, and (b) from P. decorata by the very moderate convexity of the basis. Moreover, to judge from Darwin's figures, the shell and opercular valves would seem to be considerably thinner in our species. * XIII. Genus I b la Leach. 26. I b l a q u a d r iv a l v is Cuvier. Anatifa quadrivalvis Cuv. Mem. pour servir . . . Mollusq. figs. 15-16 (1817). Ibla quadrivalvis Darwin, ‘ Lepadidae,' p. 203, pi. iv. fig. 9 (1851). Loc. Pulau Bidan, Penang. Numerous specimens. XIY. Genus Lepas Linn. 27. L epas an se r if e r a L in n . Lepas anserifera Linn. Syst. Nat. (1767); Darwin, ‘ Lepadidae,' p. 81, pi. i. fig. 4 (1851). Loc. Patani. Two specimens. XV. Genus D ich e la sp is Gray. The following key to the species of this genus is partly based on that given by Hoek in the Report on the Cirripedia collected by the ‘ Challenger,' and amplified by Stebbing in the ‘ Annals and Magazine of Natural History,' (6) xv. p. 21 (1895); but I have modified it somewhat in Group B, owing to the relatively larger number, namely eight, of new species which now have to be included in that group. A . Carina terminating in a disk. Basal segment of scutum narrower than occludent Tergum axe-shaped. Edge crenate .................................................... Edge smooth .................................................... Basal segment twice as broad as occludent............... Basal segment thrice as broad as occludent. Tergum narrowing anteriorly ............................. Tergum widening anteriorly................................ D. grayii Darwin. I), pellucida Darwin. D. warwickii Darwin. Z). antigum Stebbing. I), hoeki Stebbing. |