COOKE : NOMENCLATURE OF BRITISH NUDIBRANCHIATA. 59 



4.— Buliminus (Petrseus) somaliensis, n. sp. 



Testa ovata, supra acuminata, umbilicata, tenuis, subpellucida, fusco- 



coinea, sericata, costellis tenuibus obliquis arcuatis 



confertis sculpta ; spira convexe conica, ad apicem 



baud acuta ; anfractus 7 convexiusculi, supremus 



Isevis, cseteri mediocriter convexi, regulariter crescentes, 



ultimus elongatus, antice oblique lente descendens ; 



apertura inverse auriformis, longit. totuis ^ fere eequans; 



peristoma tenue, marginibus vix conniventibus, rallo 



tenuissimo junctis, dextro vix incrassato, anguste ex- 



\^ , panso, columellari late reflexo, intus subplicato. Longit. 



"^"-^^-^ 18 millim., diam. 9^. Apertura 8 longa, 5 lata. 



Hah. — Ganlibah Goles Range, 5900 feet. 



Remarkable for its thin texture and the delicate unthickened lip. 

 The costulse are very fine, and gradually become more numerous as 

 the shell increases. The obsolete fold on the columella is only seen 

 when the aperture is viewed in a particular position with the outer lip 

 towards the eye. 



NOTES ON THE NOMENCLATURE OF THE BRITISH 



NUDIBRANCHIATA, WITH A DETAILED 



CLASSIFICATION OF THE GROUP. 



By the Rev. A. H. COOKE, M.A., F.Z.S., 



Felloiv and Tutor of King's College, Cambridge. 



The descriptive catalogue of the British Nudibranchiata given by 

 Jeffreys, Brifii^li Conch., vol. v, pp. 28 — 94, was prepared for him by 

 Alder (ibid. p. 27), Jeffreys himself not having made a special study 

 of the group. I have recently had occasion to examine the references 

 for the authorship of the names of the various species, as given in 

 those pages. It appeared j^ossible that the results might be of more 

 than private interest, since it is exactly 30 years since that volume 

 appeared, and the researches of Herdman, Garstang, and many others 

 have done much to call attention to a branch of our Mollusca which 

 has been strangely neglected, and which is of surpassing interest, 

 from more than one point of view, to the practical zoologist. They 

 have therefore been put into a tabular form, following the pages in 

 '■^British Cojicliologij," vol. v, with which they should be read. 



