208 MAZATLAN UNIVALVES 
?+ Patella Nuttalliana, Rve. Conch. Ic. pl. 30, f. 81, a, b. 
?+ Patella Cumingii, Rve. Conch. Ie. pl. 16, f. 37, a, b.—(Val- 
paraiso, Cuming.) 
? + Patella diaphana, Nutt. non Ave. (v. supra, p. 203.) 
= Lottia pintadina, (pars,) Gould, loc. cit. in p. 203. 
Comp. Patella clypeater, Rve. (as of Less. Voy. Cog. p. 419) 
Conch. Ic., pl. 16, f. 37, a, b. (Valparaiso, Cuming.) 
I have the authority of Mr. Nuttall, after a careful collation 
of his specimens and those of Dr. Gould, for placing together 
his species above quoted. The ordinary form of the shell 
greatly resembles A. mesoleuca, but without the green tinge. 
The pattern, which distinguishes many of the above species, 
often changes in the same shell. Whether the shells of N. 
and S. America are the same, is not yet decided. The extreme 
form is a large solid white shell, with a broad black rim. To, 
this belong the only two specimens found in the Mazatlan 
collection. Mr. Reeve, who most obligingly named the Maz- 
atlan lhmpets according to his monograph, affiliated these, and 
some of the dark-margined specimens of A. mesoleuca as their 
young, to P. striata, Quoy & Gaim. Their species is different ; 
but the young are most probably his own P. striata, sp. 99, from 
the Gallapagos. The A. scutum of Esch. is quite different 
from the large flat shell with a rich metallic lustre, which often 
goes by that name in collections; this occurred in abundance 
at S. W. Mexico, P. P. C., and is from Monterey, Mus. 
Cum.— The largest Mazatlan specimen measures Jong. 1°5, 
lai. 1°23, alt. °57. 
Hah.—Sitcha, Eschscholtz, Wosnessenski—Kenai Bay, do.— 
Aleutian Is., Unalashka, Kastaljski—Tugur Bay, Schantar 
Is., Middendorff—California, passim, Nuttal/.—Monterey, 
San Diego, Lieut. Green —Mazatlan ; 2 fresh sp. ; L’pool 
Col.—(?) Chili, Bolivia, Peru, D’ Orbigny. 
Tablet 1007 contains the most characteristic specimen. 
266. Acmma PERSONA, Esch. 
Esch. Zool. Atl. p. 20, pl. 24, f.1,2.—Mid. Mal. Ros. pt. ii. 
wp i. 1.3. 
+Jun.=A. radiata, Esch. loc. cit.. p. 20, no. 8, (teste Mid.*) 
+A.ancylus, Esch. loc. cit. p. 20, no. 10, pl. 24, f. 4 bis, 6. (do.) 
* Philippi however (loc. cit. supra) regards A. radiata and A. ancylus as 
forming a different species not from N. America, but from Chili, 
