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°. 
Hab.—Mazatlan ; 10 sp. off Chama & Spondylus; L’pool Col. 
Tablet 1591 contains 4 sp. of different ages. 
386. CERITHIUM ————, sp. ind. (6.) 
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 coste. 
Hab.—Mazatlan ; 1 sp. off Spondylus ; L’pool Cel. 
387. CERITHIUM STERCUS-MUSCARUM, Val. 
Rec. Obs. Humb. & Bonpl. vol. ii. p. 278. 
Bes Sama irrézatum, Gould, Prec. Bost, Soo. Nat. Hist. 1849, 
p. 1fQ:—Evp. Shells, p. 61.—C.B. Ad. Pan. Shells, p. 154, 
no. 200. 
Cerithium ocellatum, Mike. in Zeit. f. Mal. 1850, p. 178, no. 40.— 
Sow. Thes. Conch. sp. 69, pl. 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. interruptum, 
which he attributes to Gould instead of to Menke, and to 
which it has no resemblance. JBrugiére’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; aud the entire freedom of the speciraens from the 
usual aceretions, 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. Lf 
Ss 
