128 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Subgenus Parvilucina Dali, 1901. 
Phacoides tenuisculptus Carpenter, 1865. 
Plate 15, fig. 6, and plate 33, figs, la, lb. 
Suppl. Rep. Brit. Assoc., p. 642. Proc. U. S. N. M., 23; pi. 40, fig. 5. 
Shell small, orbicular, deeply convex, thin; umbones prominent, cen¬ 
tral; surface sculptured by numerous fine, concentric lines and radiating 
striae; lunule prominent, the greater part being in the right valve; cardinal 
teeth small, laterals prominent; anterior muscle-impressions not as elon¬ 
gated as in P. acutilineata and others. Length, 2-5 mm. (Arnold.) 
Type in U. S. N. M. Type locality, Vancouver Island. 
Range. Nunivak Island, Bering Sea, to Coronado Islands, Lower 
California. In the Pleistocene at San Pedro and San Diego and the 
Pliocene at San Diego Well. 
Phacoides approximatus Dali, 1901. 
Proc. U. S. N. M., 23 :828; pi. 39, fig. 4. 
Shell small, tumid, nearly equilateral, white with a yellowish perios- 
tracum; beaks high, full with a rather emphatically depressed lanceolate 
lunule; sculpture of numerous fine, rounded, usually entire riblets sepa¬ 
rated by narrow sulci on the disk, but absent from the dorsal areas; 
concentric sculpture of low, feeble, distant, elevated lines which become 
feebly lamellose on the dorsal areas; hinge, especially the laterals, strong, 
normal; muscular scars as usual; basal margin conspicuously crenulated. 
Length, 6.3; height, 6.5; diameter, 4 mm. (Dali.) 
Type in U. S. N. M. Type locality, Gulf of California? 
Range. Monterey, California, to Panama. 
Genus DIVARICELLA Martens, 1880. 
Valves suborbicular, convex, subequilateral, with inconspicuous beaks, 
no dorsal areas, two cardinal teeth in each valve, the laterals variable, the 
posterior distant, usually obsolete; the anterior feeble, adjacent; ligament 
and resilium set in a groove, but not internal, the excavated striae forming 
an angle on a line radial from the beaks. 
Type. Lucina ornata Reeve. 
Distribution. Practically universal. 
Range in time. From the Eocene. 
Divaricella perparvula Dali, 1901. 
Proc. U. S. N. M., 23 :815; pi. 39, fig. 8. 
Shell small, globular, with rather sparse external sculpture, more 
tumid than the young of D. eburnea . A new name for D. pisum Philippi. 
(Dali.) 
