361 



marked by exceedingly fiae, obscure, closely-arranged, concentric striae, 

 which are crossed on the posterior umbonal slopes by a few stronger 

 radiating lines, extending from near the beaks to the posterior and pos- 

 tero-basal margins. Hinge and interior unknown. 



Length and height, 0.15 inch ; breadth or convexity, 0.12 inch. 



This delicate little shell resembles Cardium suhquadrattmi of Evans and 

 Shumard, but is much more gibbous, and more rounded in outline, than 

 specimens of that species of its own size. It also differs in having much 

 more distinct radiating lines on its posterior side ; those on Cardium sub- 

 quadratum being almost entirely obsolete. In the roundness of its out- 

 line, as well as in the gibbous character of its valves, it approaches Car- 

 dium rarum of Evans and Shumard ; still, its posterior margin is more 

 truncated, and its radiating lines much more distinct. It likewise differs 

 from both of these species in being a much smaller shell than either of 

 them ; though it may be the young of even a larger species. 



Mr. Gabb has described two Cretaceous species of this group in the 

 California Geological Eeports, under the names Protocardia Placerensis 

 and P. translucida, that may, one or both, be related to this, though they 

 differ in outline. 



Locality and position. — Komooks, Vancouver's Island; Cretaceous. 



Genus CYPRIMERIA, Conrad. 

 Cyprimeria? TENUIS, Meek. 



Plate 2, figs. 5, 5 a, and 5 i. 



Bosinia? tenuis, Meek (1861), Proceed. Acad. Nat. Sci. Philad., siii, 315. 



Shell circular or slightly oval, extremely thin, and mach compressed ; 

 lateral and basal margins regularly rounded, very thin, and sharp ; 

 beaks small, compressed, central, projecting little above the dorsal mar- 

 gin ; luuule small and rather deep ; surface marked by fine concentric 

 striae. 



Length and height each 1.26 inches; convexity about 0.22 inch. 



I have merely placed this species provision ally in the genus Cyprimeria, 

 not having seen specimens showing either the hinge or other internal 

 characters. It has much the appearance of a Lucina, but some of the 

 internal casts appear to show that its anterior muscular impressions are 

 not as in that genus, while they also give indications of a double oblique 

 tooth just in front of the beaks, more nearly as "we see in Cyprimeria.* 

 It is a rather common species, and will be readily identified by its cir- 

 cular compressed form and extreme thinness. It is closely allied, so ■ far 

 as regards general appearance, to Artemis lenticularis of Forbes from 

 the Cretaceous at Pondicherry, Southern India (Trans. Geol. Soc. Loud., 

 vol. vii, pi. 18, fig. 7). 



Locality and position. — At several places near isauaimo, Vancouver's 

 Island, and on New Castle Island: Cretaceous. 



* In the cast represented^by figs. 5 a and 5 h. the tooth does not show its double char- 

 acter >io clearly as others. 



