MAZATLAN UNIVALVES 481 
minute spiral strie. The operculum when perfect presenta 
the remarkable feature of a finely plaited border round the 
labral external margin. An unusually elevated specimen 
measures long. 4°23, long. spir. °36, lat. °92, div. 80°. 
Anormalsp. .,, 1°2, _ pau oe ano OG. er Choe 
A depressed sp. ,, ‘84, ie Oe tt SO) 01 gee 
Hab.—Mazatlan, 1 sp. Botta.—Charles Is., Galapagos; under 
stones at low water; Cwuming.—Taboga; very rare, same 
station, and in crevices of rocks near low water mark ; 
C. B. Adams.—Mazatlan; rare, generally encrusted with 
coralline ; L’pool Col. . 
Tablet 2252 contains an adult sp. with Bryozoa, remarkable 
_ for a shagreening of the surface, and (in this specimen alone) 
for along process from the labrum not seen afterwards. The 
normal portion displays a seulpture which may develop into 
P. muricata. 
Tablet 2253 contains 3 sp. elevated.—2254, 3 do. normal.— 
2255, 3 do. depressed.—2256, 1 sp. with operculum, and one 
separate operculum. 
Genus CUMA, Humph. 
Swains. Treat. 1840, p. 307 :—H. & A. Ad. Gen. vol. i. p. 133. 
A convenient, though not very distinctly defined group of 
Purpure auct. The plait in the typical species, Cuma tectum, 
(S. W. Mexico, P. P. C.) does not appear of more generic 
importance than the fold in Purpura columellaris. 
609. CUMA KIOSQUIFORMIS, Duel. 
Purpura kiosquiformis, Duc/. in Ann. Sc. Nat. vol. xxvi. p. 107, 
pl.l, f. 5, 1832.— Hien. Icon. Conch. p. 59, pl. 15, f. 40.— 
Desh. in Lam. An. s. Vert. vol. x. p. 96, no. 60.—Hyd. & 
Soul. Voy. Bon. Moil. pl. 39, f. 23-5 :—B. M. Cat. no. 194, 
p. 24.—Rve. Conch. Ic. pl. 7, f. 31, var.—Gray, Fig. Moll. 
An. pl. 87 a, f.6.—C. B. Ad. Pan. Shells, p. 77, no. 71. 
Var.=P. scalariformis, D’ Orb. B. M. Cat. Moil. p. 41, no. 359: 
(P=P.s., Lam. An. s. Vert. vol. x. p. 78, no. 20).—= Purpura, 
sp. ind., C. B. Ad. loc. cit. p. 78, no. 72. 
Cuma kiosquiformis, H. & A. Ad. Gen. i. 134; pl. 14, f. 3. 
This remarkably variable shell is sometimes short and angular 
| like the Turbinelloid C. tectum; sometimes with the periphery 
Feb. 1857. ss 
