268 MAZATLAN UNIVALVES 
are often by no means constant. It has been the object, in 
the following selection from the multitudes of individuals in the 
Mazatlan collection, to illustrate the variations of which each 
species is susceptible.* 
334, CREPIDULA ACULEATA, Gmel. 
Patella aculeata, Gimel. p. 3693.—Dillw. Deser. Cat. p. 1020, 
no. 11. 
Patella fornicata aculeata, Chemn. Conch. Cah. vol. x., p. 334, 
pl. 168, f. 1624-5. 
Patella fornicata, var. Schreth. Conch. vol. i. p. 338. 
La Retorte épineuse, Favanne, vol. i. p. 564, pl. 4, f. F. 2. 
Crepidula aculeata, Lam. An. s. Vert. vol. vii. p. 642, no. 3.— 
Desh. Enc. Meth. Vers, vol. ii. p. 27, no. 11.—Sow. Gen. 
f.4.—B. M. Cat. Cuba Moll. p. 33, no. 395.—B. M. Cat. 
D Orb. Moll. p. 48, no. 415.—?? Brod. in Proc. Zool. Soe. 
1834, p. 39.— Gould, ms. Cat. Cal. Shells —Dkr. Ind. Moli. 
Guin. no. 94.—Krauss Sudafr. Moll. p. 69, no. 4. 
Crepipatelia aculeata, H. § A. Ad. Gen. 1. 369. 
+Crepidula Capensis, B. M.: (?= Quoy § Gaim. Voy. Astr. 
vol. ii. p. 424, pl. 72, f. 13,14;—Lam. An. s. Vert. vol. vii. 
p. 645, no. 9:—Krauss, Sudafr. Moll. p. 68, no. 1.) 
+Calyptrea (Crepipatella) echinus, Brod. in Proc. Zool. Soc. 
1834 p. 39.—Trans. Zool. Soc. vol. i. p. 203, pl. 27, f. 1— Mull. 
Syn. Nov. Test. Viv. p. 148.—H. & A, Ad. Gen. i. p. 369.— 
(Crepidula e.) Lam. An. s. Vert. vol. vii. p. 650, no. 23.— 
C. B. Ad. Pan. Shells, p. 226, no. 344. 
+Calyptrea (Crepipatella) hystrix, Brod. Proc. Zoel. Soc. 
1834, p. 39:—TZrans. Zool. Soe. vol.i. p. 203, pl. 29, f. 2.— 
HT. & A. Ad. Gen. i. p.369.—(Crepidula h.) Lam. An. s. Vert. 
vol. vii. p. 650, no. 22. : 
+ Crepidula costata, Whe. in Zeit. f. Mal. 1847, p. 183, no. 32 : 
(non Sow. nee Quoy, nee Desh. in Lam. An. s. Vert. vol. vii. 
p. 644, no. 7.)—Id. 1851, p. 35, no. 122. 
+ Crepidula Californica, Nutt. ms. in Warrington Mus. 
= T have been compelled to unite several species usually regarded as very dis- 
tinct. On shewing a series to an author deservedly distinguished, proving that 
four species were identical which he had grouped under two subgenera, he com- 
plained that I had kept all the puzzling shells! It is easy, as one naturalist is 
recorded to have done, to smash all specimens not according with our classifica- 
tion; or as another, to pick out all the leading forms and describe them as 
distinct species, genera, or even orders, disregarding the intermediate ones which 
would have proved them identical; but the interests of science are not served by 
either one course or the other. Our object must ever be, not to make Nature 
speak our language, but to find out what is the language of Nature, 
