378 
/ MAZATLAN UNIVALVES 
442. TRIVIA sanGUINEA, Gray. 
Deser. Cat. p. 14, no. 119.—H. & A. Ad. Gen. i. 269. 
Cyprea sanguinea, Sow. Cat. Cypr. p. 12, no. 115 :—Conch. Til. 
pl. 6, no. 32.—Lam. An. s. Vert. vol. x. p. 570, 102.—Rve. 
Conch. Ic. pl. 23, f. 127.—Chén. Lec. Elem. pl. 10, f. 9, 10.— 
Mke. in Zeit. f. Mal. 1847, p. 183, no. 29:—1851, p. 34, 
no. 114.—C. B. Ad. Pan. Shells, p. 38, no. 12. 
+ Cyprea fusca, Gray in Sow. Conch. Ill. no. 120, f. 37.—Rve. 
Conch. Ic. pl. 24, sp. 134.—Mke. in Zeit. f. Mal. 1851, p. 34, 
no. 115. (Galapagos & Bay of Guayaquil, Cuming.) 
Comp. Cyprea rubescens,* Gray, Proc. Zool. Soc. 1832, 
p. 185.— Rve. Conch. Ic. pl. 25, sp. 141.—C. B. Ad. Pan. 
Shells, p. 38, no. 11. (Galapagos, Cuming.—Panama, C. B. 
Adams.) 
After very careful and repeated examinations of many 
hundred specimens, I feel unable to separate the C. fusca from 
the C.sanguinea. The colour varie¥ from very dark brownish 
purple, with blood-red stain on the back, to a brown with 
scarcely any admixture of purple or red; and again to a general 
reddish pink, like C. rubescens. The differences of shape, 
from a:ounded form approaching T. subrostrata to an’ elonga- 
tion approaching T. suffusa, do not accompany the differ- 
ences of colour, but are found in each state. The swelling at 
the basal margins is very variable. The sculpture is by no 
means constant, the ribs (of uncertain number) being continu- 
ous over the back, or variously interrupted ; intercalations and 
confluences frequently appearing. The columella is broadly 
indented over the whole length, with a wave in the middle. 
The smallest sp. measures long: 22ilac Lal Pe ale. 1G. 
The largest sp. w SER Ms 5 Roenremgae: i Le chsh yf ARG? Bae 
An elongated sp. i Saale” Veter Ox lars MMiey an 
A broad sp. as oP ASR As ve oy. 8 eae Nets 
Hab.— Panama and Mexico, Sowerby.—St. Elena, under 
stones, Cuming.— Panama, one dead sp. C. B. Adams. — 
Mazatlan; abundant, (generally dead ;) Z’pool Col. 
Tablet 1796 contains 5 sp. dark brownish purple, red stain 
developed.—1797, 4 do. red scarcely appearing.—1798, 5 sp. 
dark brown, red stain slight.—1799, 4 do. red evanescent.— 
* The specimens of T. fusca and T. rubescens in Mus. Cuming seem to be 
extreme varieties of T. sanguinea. Those in Mus, Gaskoin however appear dis- 
tinct, especially of the form rubescens. 
