492 MR. H. K. RIDLEY ON THE 



former* that T. cyclostoma, T. niilila, T. ci/linch-acea, and the 

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



25. Ianthina fragilis, Lamarck. 



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

 identified as Lamarck's I. fragilis (Couch. Icon, pi ii. ft". 6^, G^) 

 closely resembles the shells from Ternaudo Noronha. They have 

 the same perpendicular columella and the same divisiou of colour, 

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

 jjeriphery. 



26. Cerithium atratum {Born). 



Hah. West Indies, Peruambuco, and Eio Janeiro {Brit. Mus.). 



I regard the C. caudatiim of Sowerby as undoubtedly belonging 

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

 ' Thesaurus Couchyliorum ' and in Eeeve's ' Conchologia Iconica ' 

 to C. atratum, is evidently incorrect. 



27. MiTRULARIA ALVEOLATA {A. Adams). 



Calyptraea alveolata, A. Adams, Reeve, Con. Icon. vol. xi. pi. 3. tf. 8 a-b. 



Hah. Gralapagos Islands {Beevc); 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 Noronba, assigned with doubt to M. 

 uncinata, lieeve, by Watson f, in all probability belong to the 

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

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

 more difficult. 



28. HippoNYX ANi'iQUATUs {Llnue). 



Hipponyx antiquatus (L.), Fischer, Journ. cle Conch, vol. x. ]). 5, pi. ii. 

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

 Bldtt. vol. xxiv. p. 98. 



Hah. AVest Indies ; islands of 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. 



* Conch. -Cab., Solaritiin, p. 20. 

 i' ' Challenger ' Gastropoda, j). 461. 



