318 MAZATLAN UNIVALVES 
other seas; these, from the sponge of commerce, and from the 
tsle of France (Bean) appear distinct ; those from “Singapore” 
(among Chame and Plicatule, P. P. C.) offer no grounds of 
specific separation. I have not however ventured to insert 
them in the habitat, asa larger series of perfect shells may 
shew distinctive characters. From Mazatlan traces were found 
(including varieties) of 51 specimens, of which about 20 were 
perfect, and 4 possessed their opercula. 
The smallest measures long. ‘047, lat. °O17. 
The longest 4 » °145, ,, °015—'025. 
The largest 4 SHA) oy aa OD <5 or: 
Hab.— Mazatlan ; very rare, off Chame, Spondyli, Xe. ; 
_L’pool Col. 
Tablet 1518 contains 7 specimens varying in age and sculp- 
ture, witha fragment having C. firmatum interwedged.—1519, 
1 fresh sp. with operculum ; ribs close and deeply chiseled. 
Var. TENUILIRATUM ; f¢. liris crebris, tenuibus ; apice parum 
prominenti. Tablet 1520 contains 1 specimen. 
Var. sUBoBsoLEetuM ; ¢t. albd, alabastro simili; liris paucis 
interdum vix monstrantibus. Tablet 1521 contains a young 
and an adult specimen. 
Var. suBcoNicUM ; ft. septo maxime elevato, subconico. Tablet 
1522 contains a perfect, and a Worn specimen. The latter 
appears to have its apex subcentral, and may be distinct. The 
value of the several distinctions above named cannot be tested 
till more specimens are procured. 
Among all the specimens of Mazatlan Ceca, only one was 
found with its spiral apex. It was so extremely frail that (not 
however until after careful observation) it dropped off on touch- 
ing with a camel hair pencil. This portion possessed two whirls, 
of somewhat irregular flattened growth, differing in texture 
from Vitrinella, and much smaller, measuring only *006 by *004. 
About half a whirl however remained on the shell, separated 
from the normal part by avery distinct suture. On removing 
this, it was found that no plug had yet been formed. The 
species is therefore indeterminate, as the shell is in the main 
smooth, with extremely faint traces both of concentric and long. 
itudinal sculpture. It is placed provisionally under C. lirato- 
cinctum. The normal part measures long. ‘028, lat. *0045—' 002. 
Tablet 1523 contains the specimen. 
