MAZATLAN UNIVALVES 337 



not appear in the earliest whirls. The outlines are more or 

 less convex, according to the prominence or otherwise of par- 

 ticular keels. None of the specimens were mature, but no 

 species has been found resembling it. The smallest sp. with 

 5 whirls, measures '032 by '023. The largest, long. '122, 

 long. spir. '075, lat. '067, div. 32. 



JTab. Mazatlan ; 10 sp. off Chama & Spondylus ; L'pool Col. 

 Tablet 1591 contains 4 sp. of different ages. 



386. CERITHIUM , sp. ind. (b.) 



Tablet 1592 contains an imperfect specimen, closely resem- 

 bling a West Indian species. It is of an orange brown, with 

 not numerous radiating tri-tuberculous costae. 

 Hal). Mazatlan ; 1 sp. off Spondylus ; L'pool Col. 



387. CERITHIUM STERCUS-MUSCAEUM, Vol. 



JRec. Obs. Hwmb. fy Bonpl. vol. ii. p. 278. 

 = Cerithium irroratum, Gould, Proc. Host. Soc. Nat. Hist. 1849, 

 p. 119 : Exp. Shells, p. 61. C. B. Ad. Pan. Shells, p. 154, 

 no. 200. 



Cerithium ocellatum, Wee. in Zeit.f. Mai. 1850, p. 178, no. 40. 

 Sow. Thes. Conch, sp. 69, pi. 179, f. 59, 77. (?Non C. ocella- 

 tum, Brug. no. 43 : Lam. An. s. Vert. vol. ix. p. 303, no. 30.) 

 Sowerby strangely unites to this species the C. interruption, 

 which he attributes to Gould instead of to Menke, and to 

 which it has no resemblance. Brugiere's is probably the 

 African shell, specimens of which are in the Br. Mus. from 

 Madagascar. They most closely resemble the Pacific species, 

 and may hereafter be proved identical. Of the very numerous 

 specimens sent of this shell, extremely few were quite adult, 

 and very few young. In its ordinary state, it has a Pirenoid 

 aspect ; and the entire freedom of the specimens from the 

 usual accretions, the erosion of the apical whirls, and the dark 

 hue, would have led us to consider it a brackish water shell, 

 were it not for the contrary testimony of Prof. Adams. The 

 spire has one row of stout tubercles, but there are no granules. 

 The mouth is generally of a lustrous black, usually broadly 

 notched at the base ; when adult, rounded, with labial callosi- 

 ties bounding the notch and the short posterior canal. From 

 Sept. 1856. ff 



