492 



MR. H. N. RIDLEY ON THE 



former* that T. cyclostoma, 1\ nuUla, T. cylindracea, and the 

 present species are mere varieties of one and the same form. 



25. Ianthina fragilis, Lamarch. 



Of the various species figured by lieeve, that which he has 

 identified as Lamarck's I. fragilis (Conch. Icon, ph ii. . 6 6 1) 

 closely resembles the shells from Fernando Noronha. They have 

 the same perpendicular columella and the same division of colour, 

 the " deep-violet " tint of the base terminating abruptly at the 

 periphery. 



26. Cerithium atratum {Born). 



Hob. West Indies, Pernambuco, and Eio Janeiro {Brit. Mus.). 



I regard the G. caudatim of Sowerby as undoubtedly belonging 

 to this species. " Sicily," the locality assigned by Sowerby in the 

 * Thesaurus Conchyliorum ' and in Eeeve's ' Conchologia Iconica ' 

 to G. atratum, is evidently incorrect. 



27. MiTRULARIA ALYEOLATA {A. Adams). 



Calyptrsea alveolata, A. Adams, Reeve, Con. Icon. vol. xi. pi. 3. ft". 8 a-h. 

 Hal. Gralapagos Islands {Beeve); St. Kitts, West Indies 

 {Brit. Mus.). 



The single shell from Fernando Noronha possesses all the 

 characteristics of the type from the Galapagos Islands. The 

 specimens from Fernando Noronha, assigned with doubt to M. 

 tmcinata, Eeeve, by Watson t, in all probability belong to the 

 same species as that collected by Mr. Eidley. They are, how- 

 ever, only young specimens, so that their determination is all the 

 more difiicult. 



28. HiPPONYX ANTiQUATUS {Limie). 



Hipponyx antiquatus (L.), Fischer, Journ.de Conch, vol. x. p. 5, pi. ii. 

 ff. 1-9 (anatomy) ; Crosse, Journ. de Conch, vol. x. p. 20 ; Morch, Malak. 

 Bldtt. vol. xxiv. p. 98. 



Hah. West Indies ; islands o£ Ascension, St. Helena, and 

 Trinidad in the South Atlantic, Peru and California {Brit. Mus.). 



The single specimen from Fernando Noronha has the spire 

 more recurved than any other specimen I have seen and it is 

 inclined to the left. 



* Concli.-Cab., Solarium, p. 26. 

 t ' Challenger ' Gastropoda, p. 461. 



