CLASS PELECYPODA 
97 
Family LYONSIELLID2E. 
Genus LYONSIELLA M. Sars, 1872. 
Shell small, thin; lunule faint or none; ossicle semi-cylindrical, forked 
behind; external ligament almost none; right valve edentulous, lunular 
edge a little produced and thickened; left valve with an elongate obscure 
thickening of the hinge-margin under the beak. 
Type. Lyonsiella abyssicola Sars. 
Distribution. North Atlantic and north Pacific in deep water. 
Lyonsiella alaskana Dali, 1894. 
Proc. U. S. N. M., 17:703; pi. 25, fig. 2. 
Shell thin, large for the genus, inequilateral, the anterior end shorter 
and more vertical, the posterior end more rounded; covered with a yellow, 
silky epidermis considerably infolded around the margins of the valves; 
sculpture of fine, distant radiating, elevated threads about half a millimeter 
apart near the margin; the interspaces crossed by silky lines of growth 
which are occasionally emphasized as if at resting stages of growth; 
interior faintly pearly; hinge line edentulous, with a large lithodesma 
shaped like a flattened shell of Vaginella, with a deep sinus in the wider 
(posterior) end; beaks moderately prominent, much incurved; lunule 
larger on the right valve, small heart-shaped, polished; a narrow polished 
strip on the posterior dorsal edge of the valves may represent an 
escutcheon. Length of shell, 24; height, 24; diameter, 16 mm. (Dali.) 
Type in U. S. N. M., No. 123500. Type locality, Station 2859, in 
1659 fathoms green ooze, southwest of Sitka. 
Range. Southwest of Sitka to ofif Catalina Island, California. 
Family CUSPIDARIDyE 
Genus CUSPIDARIA Nardo, 1840. 
Shell globular, attenuated, and gaping behind; right valve a little the 
smaller; umbones strengthened internally by a rib on the posterior side; 
cartilage process spatulate, in each valve (furnished with a movable 
ossicle, according to Deshayes), with an obsolete tooth in front and a 
posterior lateral tooth; pallial sinus very shallow. 
Type. Tellina cuspidata Olivi. 
Distribution. Norway, Britain, Mediterranean, Canaries, Madeira, 
China, Chili, Moluccas, New Guinea, California, Washington, Oregon. 
Range in time. Oolite of Britain, Belgium, Italy. 
