224, MAZATLAN UNIVALVES 
_ plaited spiral frill, prickly inside. Between this and the outer 
margin are 4—6 (generally 5) fine emerald necklaces, supported 
on slender spiral ribs, with deeply channeled interspaces. The 
margin and the body of the operculum are white. The oper- 
culum of its neighbour, C. saxosum (Panama, C. B. Adams, 
S. W. Mexico, P. P. C.) is formed ona much coarser plan, 
with the central callus not covering the umbilicus, the frill 
rather granular than plaited, the three rows of necklaces close 
together, without deep channels, and with large granules on 
the margin. All the Mazatlan shells were of the typical form, 
with the spire elevated, whirls well rounded, with distant rows 
of nodules. Whether the C. f. depressum is a variety of this 
form, (as I described it in the P. Z. S., copying Reeve’s error 
in the name, and not aware that Kiener had figured it,*) 
or another species, cannot be decided without a knowledge 
of the operculum. The shell is distinguished from all varieties 
of C. saxosum, by the non-corrugation of its surface. Long. 2°56, 
lat. 2°5, div. 90°. 
Hab.— Punta St. Elena, Cwming.— Mazatlan ; abundant ; 
LI’ pool Col.—San Diego, Lieut. Green.—Sitka, Wosnessenski, 
Middendorff. 
Tablet 1081 contains the largest specimen, in its natural 
rough state.—1082, the sp. which suffered least from hot acid.— 
1083, 6 opercula of different ages, and of exquisite beauty. 
Genus PHASIANELLA, Zam. 
Lam. Phil. Zool. 1809.—Phil. Handb. Conch. p. 205. 
Kutropia, (Humph.) Gray, 1847. —H. &§ A. Ad. Gen. vol. i. 
p. 389. 
Phasianus, Montf. 1810.—Tricolia, Risso, 1826. 
283. PHASIANELLA PERFORATA, Phil. 
Zeit. f. Mal. 1848, p. 164, no. 34.—Kust. Mart. p. 20, sp. 24, 
pl. 4, f. 14: 
Comp. Phasianella tessellata, Beek, 1838, Pot. et. Mich. Gall. 
vol. i. p. 312, pl. 29, f. 7,8.—C. B. Ad. Contr. Conch. 1850, 
p. 67.—Phil. in Kust. Mart. p. 18, sp. 22, pl. 4, f. 12.—=Ph. 
minuta, Anton, 1839, Verz. p. 60, no. 2129, (non Sow.)—= Ph. 
_* I have seen no letter-press in explanation of the figure, nor are any dates 
given in Kiener’s monographs, by which questions of priority can be determined. 
