284, MAZATLAN UNIVALVES 
1409, 1 sp. finely developed, with coloured rays, lamine con- 
eentrically striated. 
Aberrant specimens. Tablet 1410 contains 1 sp. longitudin- 
ally ribbed (from adherent surface.) — 1411, 7 sp. margin 
irregular.—1412, 3 sp. margin curved.—1413, 3 sp. flat and 
recurved, form of C. unguiformis.—1414, 6 sp. posterior margin 
expanded.—1415, 3 sp. subspiral, approaching C. aculeata.— 
1416, 1 sp. deck elongated.—1417, 3 do. deck very short.—1418, 
3 do. colour developed inside, brown passing into green.—1419, 
1 sp. shewing under layer of deck, striated.—1420, 1 do. dis- 
eased.—1421, 1 do. deck solid, as in C. onyx.—1422, 1 do. flat, 
concentric strie conspicuous.—1423, 3 do. longitudinally cor- 
rugated. 
Tablet 1424 contains a portion of Spondylus ealcifer, pre- 
sented by R. D. Darbishire, Esq. containing in situ 4 sp. 
Petricola robusta, 1 Cumingia, 2 Lithophagus plumula, 1 Gas- 
trochena truncata, and 1 Crepidula nivea. This is greatly 
elongated, 1°55 by *72, much arched, and with very numerous 
layers. Its position in a burrow of Lithophagus has preserved 
the apex from detrition.—1425, 1 sp. still more elongated, from 
the burrow of a Lithophagus in Chama, closely resembling 
C. explanata, Gould. 
Specimens shewing deck margin. Tablet 1426 contains’ 3 sp. 
sinus slight, center more or less. deeply angulated.—1427, 6 sp. 
sinus deep, center nearly straight, more or less angulated or 
sinuated.—1428, 1 sp. with abnormal central ridge. 
, Tablet 1429 contains 2 young shells which probably belong 
to this species, though the apex has been rubbed smooth. 
342. CREPIDULA PUNGUIFORMIS, Lam. 
Patella crepidula, Linn. Syst. Nat. p. 1257, no. 752.—Dillw. 
Deser. Cat. p. 1021, no. 13. 
Crepidula unguiformis, Lam. An. s. Vert. vol. vii. p. 642, 
no. 4.—Brod. Proc. Zool. Soc. 1834, p.39.—C. B Ad. Pan. 
Shelis, p. 230, no. 350.—(Ianacus u.) H. & A. Ad. Gen. 1. 
p. 370. 
Crepidula Italica, Defr. Dict. Sc. Nat. vol. xi. p. 397. 
Crepidula plana, Say, Journ. Ac. Nat. Se. Fhil. vol. ui, p. 226. 
(teste Gould & C. B. Ad. non Desh.) 
Comp. Patella Goreensis, Gimel. p. 3694.—Dillw. Deser. Cat. 
p. 1020, no. 12.—(Crepidula G.) Desh. in Lam. An. s. Veré. 
