MAZATLAN UNIVALVES 219 
which the hole preserves the normal characters, measures 
long. °48, lat. °3, alt. 15. 
The largest sp. (elongated) 5. eit ECOG: i ae 
A normal sp. 53 tE Geen ex bsOS, : 2, Ge 
A conical sp. 1°34, 96. Nae 
Hole of largest sp. °3 by ‘12. Div. 95° by 105°. 
Hab.—Mazatlan; common; L’pool Col. 
Tablet 1058 contains 8 sp. different ages, normal state.—1059, 
3sp. elongated.—1060, 3 do. smooth.—1061, 3 do. elevated, 
nodulous.—1062, 4 sp. shewing interior.—1063, 3 sp. with singu- 
lar growth of coralline.—1064, 1 do. smooth, with Acmza 
mitella in situ.—1065, 1 do. nodulous, with dried animal of 
adherent limpet.— 2066, 2 sp. hole abnormally produced, 
(div. 85°.)—1067, 3 sp. with Balani, and attachments of limpets. 
In one (empty), a young Jsognomon has taken up its abode. 
Another (spinous) has inserted a fang through the hole of the 
shell. —1068, 3 sp. distorted growth. 
Section B. Margin smooth. 
277. FissuRELLA Peruviana, Lam. 
Lam. An. s. Vert. vol. vii. p. 599, no. 17.—B. M. Cat. D’ Orb. 
Moll. p. 51, no. 432. 
+Fissurella subrotundata, Desh. Enc. Méth. Vers, vol. ii. 
p. 135, no. 11:—Lam. An. s. Vert. vol vii. p. 602, no. 26. 
Var.=Fissurella affinis, Gray, Proc. Zool. Soc. 1834, p. 125.— 
Sow. Conch. Ill. p. 4, no. 35, f. 44. 
Cremides Peruviana, H. & A. Ad. Gen. i. 446. 
Only one specimen, and that somewhat worm-eaten, was 
found of this characteristic S. American shell. Shell very 
conic, slightly ribbed, hole nearly round. anterior side pointed, 
inside white, with a sharp, non- crenated, narrow margin, 
shaded with purplish brown. Long. 1°35, lat. 1°12. alt. ‘68. 
Hab.—Peru, Humboldt §& Bonpland—Is. Mexillones, Lobos ; 
Tquiqui and Valparaiso ; Cwming.—Mazatlan ; 1 specimen: 
LP’pool Col. 
Tablet 1069 contains the specimen. 
278. FIssURELLA SPONGIOSA, 7%. Ss. 
F. t. elongatd, compressa, conicd, antice angustiore, postice 
dilatata ; superficie externd quasi spongiosa, nec liratd nee 
striata ; viridi, juniore lineis, adulté maculis castaneis radi- 
