A. FE. Verrill on Shells from the Gulf of California. 221 
teeth nearer the cardinal, and the latter more crowded and 
stouter. 7. radiata is less regular in form than TZ. elegans, with 
much smaller sinus and broader and stouter hinge, a much 
longer ligament, sharper lateral tooth, and more numerous and 
more divergent cardinal teeth, the posterior ones being much 
more elongated. 
he name, Jrigona (Meg., 1811), is not only later than Tivela 
(Link, 1807), but was previously used among Hyemenoptera 
(Jur. 1807). It has also been used in Crustacea (Latr., 1817). 
Venus tsocardia, sp. nov. 
A large, rounded, thick, and swollen species, cordate in front, 
with a broad deeply excavated lunule; with the sculpture 
entirely concentric,—the stout, elevated, rather close, slightly 
recurved and flattened ribs separated by deep interstices in whic 
there are'several very thin, crowded, slightly elevated lamelle. 
mboes prominent, swollen, the beaks much recurved, not 
marginal; dorsal outline convex, broadly rounded and a little 
produced posteriorly ; evenly rounded ventrally; anterior end 
short, deeply indented by the very broad and sunken lunule, 
which is smoothish and surrounde by a distinct groove, broadly 
cordate, extending between the beaks. Ligamentary area nar- 
row, smooth on the left valve, the concentric sculpture extending 
over it on the right valve, which overlaps beyond the ligament. 
larger, slightly bilobed; rior one much elongated, and 
strong. ~ the left valve there is a small, conical, tubercular, 
anterior tooth ; first cardinal elevated, stout triangular; followed 
Y astout strongly bilobed one; posterior one confluent with 
the ligament plate, long and curved, less elevat 
lunule -68; length of palial sinus ‘60. : 
Near La ala ee . Pedersen. ‘Two fresh specimens. 
L is ma 
which it re 
Separated from the ligament plate, there being only a shallow 
groove between. 
Exteriorly more or less stained and blotched with brownish ; Z 7 : 
