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Show 380 SIR 0. ELIOT ON NUDIBRANCHS [Mar. I, 1. On some Nudibranchs from East Africa and Zanzibar. Part IV.* By Sir C. E L I O T , K.O.M.G., late H.M. Commissioner for the East African Protectorate, F.Z.S.- Dorididce Cryptobranchiatse, II. [Received January 23, 1904.J (Plates XXIII. & XXIV.t) [The complete account of the new species described in this communication appears here; but as the names and preliminary diagnoses were published in the ' Abstract,' such species are distinguished here by being underlined.-EDITOE.] In my last paper J I discussed the Cryptobranchiate Dorids represented by such genera as Archidoris, Discodoris, Platydoris, &c. These are oval flatfish forms, mostly of sombre coloration, with a dorsal surface rarely smooth but generally granulated, or bearing papillae, warts, or tubercles. The branchiae are usually tripinnate. A labial armature is more often absent than present, there is no central tooth, and the radula consists of uniform, simply hamate teeth, rarely differentiated or denticulate. In the present paper I propose to consider some forms belonging to another group typified by Chromodoris and its allies. These Dorids are often (but not always) elongated and limaciform in shape, brightly coloured, and smooth. The branchiae are usually simply pinnate. A labial armature is nearly always present (absent only in Thorunna and Aphelodoris). In the radula a central tooth is rare, but sometimes occurs (in Cadlina, Tyrinna, and Chr. scabriuscula), and rhachidian thickenings are frequent. The teeth are generally denticulate, and the tooth next to the rhachis is nearly always different in shape from the others. The stomach is usually enclosed in the liver, and there is rarely any armature in the reproductive organs. All these characters are well seen in Chromodoris; and I am inclined to think that the following genera are more or less closely allied to it:-Casella, Ceratosoma, Thorunna, Aphelodoris, Orodoris, Sphcerodoris, Cadlina, Tyrinna, Holla §, Rostanga, and Audura. The common character possessed by all these forms is in the mouth-parts : * For Part III. see P. Z. S. 1903, vol. ii. p. 354. t For explanation of the Plates see p. 406. X Since writing the third part of this paper (cf. P. Z. S. 1903, vol. ii. p. 354) I have read the last fasciculus by Prof. Bergh which has appeared in Semper's ' Keisen ' (Bd. ix. Th. vi. Lief. i. Nudibranchiata, January 1904), and it appears to m e that the genus Percmodoris is practically equivalent to that which I proposed to call Sclerodoris, and as it has priority should take the place of the latter name. The only difference in the generic characters is that for Peronodoris is given " penis stylo amiatus." I did not see this style in any of the forms which I have described, but even if it )s present in some species and absent in others, this variation would not in m y opmion necessitate the creation of separate genera. Archidoris violacea Bergh seems nearly allied to m y A. africana, and A. nanula Eergh to my^i. minor ; but the identity of the forms, though not impossible, cannot be demonstrated from the descriptions. § [This name is preoccupied by a Polychoete worm, Salla parthenopeia A. Costa Ann. Accad. d. Asp>ranti Naturalisti Napoli, ii. p. 63 (1844).-C. C E O S S L A N D .J |
