150 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
elevated; apex very prominent; beaks not oblique; color whitish, fre¬ 
quently rayed with brown; cardinal teeth very thick and prominent; 
anterior tooth elongated, thick; sinus of pallial impression angular. 
Length 7 inches. (Conrad.) 
This species has been called T. crass at elloides Conrad, 1834, and the 
above is Conrad’s description of that species. 
Type locality, California. 
Range. Santa Cruz, California, to Socorro Island, off the Coast of 
Mexico. In the Pleistocene at Santa Barbara and San Diego, California. 
Genus TRANSENNELLA Dali, 1883. 
Shell small, having the general form and coloration of Tivela, but a 
hinge with three cardinals in each valve, the middle left cardinal bified, 
and an elongated left lateral received into a socket in the opposite valve; 
the hinge has no rugosities, the lunule but not the escutcheon is defined, 
internal margins sharply tangentially grooved with numerous sulci; the 
pallial sinus angular, free, obliquely ascending. 
Type. Transennella conradiana Dali, 1883. 
Distribution. Tropical and subtropical. 
Range in Time. Miocene. 
Transennella tantilla Gould, 1852. 
Bost. Jour . Nat. Hist., 6:406; pi. 15, fig. 10. 
Shell quite small, rather solid, ovate-trigonal, inequilateral; beaks 
acute, surface smooth or faintly waved with distant concentric furrows; 
the dorsal margins are nearly straight, and meet at the apex in a right 
angle, but the posterior side is a fourth longer than the anterior; the 
anterior basal angle is well rounded, while the posterior is acute; basal 
margin gently curved. Color white, but the posterior third is stained deep 
slaty blue outside and in, the line of demarcation being quite abrupt and 
well defined; there is also a pencil of the same color inside, running from 
the beak to the anterior cicatrix; the rest of the interior is cream colored. 
Length, *4 i height, % inch. (Gould.) 
Type locality, Santa Barbara, California. 
Range. Sitka Harbor, Alaska, to Lower California. 
Genus AMIANTIS Carpenter, 1863 
Shell ovate, concentrically waved, with vernicose periostracum; lunule 
and a linear escutcheon defined; inner margins smooth; pallial sinus 
ample, anterior laterals large and strong. 
Type. Cytherea callosa Conrad. 
Distribution. California. 
