494 



MR. H. RIDLEY ON THE 



umbilicated than the shells figured by Eeeve * and Pischer f, and 

 also dilFer in form, being wider at the base and more shortly 

 conical. 



Pischer has already pointed out that the localities of Eeeve 

 and Lamarck, Swan Eiver and Mauritius, are probably incorrect. 



33. Trochtjs (Etjtrochus) gemmosus, Beeve. 



This I believe, as in the case of the preceding species, is another 

 instance of a wrong locality (Philippine Islands) assigned by 

 Eeeve. 



Two specimens from Ternando Noronha agree in every minute 

 detail with the types in the British Museum, and, as the sculpture 

 and lineations are so remarkable, the identity is beyond doubt. 

 The umbilicus, which is as large as that of T. jujuhinus, at once 

 distinguishes this species from T. nohilis, with which Philippi J 

 questioned its relationship. The type of Eutrochus was named 

 E. perspectivus by A. Adams ; but as that name was previously 

 used by Koch for another species belonging to the same group, 

 Pilsbury has renamed it E. Adamsi. 



34. FissuEELLA CANCELLATA, Sowerhy. 



Fissurella cancellata, Sowerby, Conch. III. sp. 38, pi. 72. f. 29. 

 Hah. "West Indies, Honduras. 



With this species I would unite Fiss. suffusa, Eeeve, and F. 

 Jentiginosa, Eeeve. A third species of the same author, F. aegis, 

 is also very similar, but the form is a little more elongate and the 

 radiating riblets are squamose at the points of intersection with 

 the concentric lirae. 



35. Fissurella alternata, Sag. 



Fissurella alternata. Say, Journ. Acad. N. Sci. Philad. 1822, vol. ii. 

 p. 224 ; Reeve, Con. Icon. pi. xii. f. 84 (probably). 

 Fissurella larva, Reeve, I. c. f 98. 

 Fissurella Dysoni, Reeve, I. c. f. 86. 



Hah. Maryland, &c. {Sag) ; Bermuda, St. Johns, Honduras 

 {Brit. 3Ius.). 



The sculpture of the three above-named forms is essentially 

 he same and the character of the orifice is similar, and all have 



* Con. Icon., Zi::yphinns, pi. 2. fig. 12. 

 t Kiener's Coq. Viv., Trochus, pi. 18. f. 2. 

 % Conch.-Oab., Trochus, p. 8G. 



