284 MAZATLAN UNIVALVES 



1409, 1 sp. finely developed, with coloured rays, laminae con- 

 centrically 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 striae conspicuous. 1423, 3 do. longitudinally cor- 

 rugated. 



Tablet 1424 contains a portion of Spondylus calcifer, pre- 

 sented by B-, D. Darbishire, Esq. containing in situ 4 sp. 

 Petricola robusta, 1 Cumingia, 2 Lithophagus plumula, 1 Gas- 

 trochaena 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 shelving deck margin. Tablet 1426 contains 3 sp. 

 ainus slight, center more or less deeply angulated. 1427, 6 sp. 

 sinus deep, center nearly straight, more or less angulated or 

 sinuated. 1423, 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. CEEPIDULA PTJNGUIFOBMIS, Lam. 



Patella crepidula, -Linn. Syst. Nat. p. 1257, no. 752. Dillw. 



Descr. Cat. p. 1021, no. 13. 

 Crepidula unguiformis, Lam. An. s. Vert. vol. vii. p. 642, 



no. &.Brod. Proc, Zool. Soc. 1834, p. 39.-* C. B Ad. Pan. 



Shells, p. 230, no. 350. (lanacus u.) H. & A. Ad. Gen. i. 



p. 370. 



Crepidula Italica, Defr. Diet. So. Nat. vol. xi. p. 397. ^ 

 Crepidula plana, Say, Journ. Ac. Nat. Sc. Phil. vol. ii. p. 226. 



(teste Gould fy C. B. Ad. non Desk.) 

 Comp. Patella Goreensis, Gmel. p. 3694. Dillw. Descr. Cat. 



p. 1030, no. 12. (Crepidula G.) Desk, in Lam. An. s. Vert. 



