14G CALIFORNIA ACADEMY OF SCIENCES. 



Subfamily Doainina. 



Genus Dosinia Scupoll. 



Shell orbicular, compressed, concentrically striated, pale, ligament sunk; lunule deep; hinge 

 like Cylherea; margin even; pallial sinus deep, angular, ascending. 



Dosinia discus Reeve ia a characteristic species. 



[S. D.] Dosinia ponderosa Gray. 



Artemis ponderosa Gray, Analyst, Vol. VIII, 1838, p. 309. 



Dosinia ponderosa Gray, H. & A. Adams, Gen. Rec. Moll., Vol. II, p. 432; =Cyiherea gigantea 



Sby. ^fide Gabb, Pal. Gal. Vol. II, p. 97, 1869). Cooper, 7th Ann. Rept. Cal. St. 



Min., 1888, p. 239. 



Shell large, thick, equivalve, subcircular in outline, convex; surface sculptured by many 



obsolete, concentric lamellje, and fine, incremental lines; lunule deeply impressed, small, finely 



sculptured; beaks small, not elevated; hinge very wide and heavy, with three heavy, cardinal teeth, 



the posterior one in the right valve being bifid; ligament long, narrow, sunken. 



Dimensions. — Long. 119mm.; alt. 105 mm.; diam. 55 mm.; lunule 15 mm. 



Commou in the upper San Pedro series (Pleistocene) of Twenty-sixtli Street, 

 San Diego. 



Living — West Mexican coast to Panama (Carpenter). 



Pleistocene. — San Diego (Hemjihill; Arnold). 



Pliocene. — Kirker's Pass, Contra Costa County; San Fernando (Cooper): 

 Stanford University, Santa Clara County (Arnold). 



Genus Venus Linne. 



Shell thick, ovate, smooth, sulcated, or cancellated; margins minutely crenulated; cardinal 

 teeth three in each valve; pallial sinus small, angular; ligament prominent; lunule distinct. 



Venus verrucosa Linne is a characteristic species. 



[S. B.] Venus perlaminosa Conrad. 



Mercenaria perlaminosa CoN., Proc. Phil. Acad. Sci., 1855, p. 267. Gabb, Pal. Cal.. Vol. II, 

 pp. 22, 55, 94; PI. V, fig. 38; PI. XV, fig. 14; 1869. Cooper, 7th Ann. Rept. Cal. St. 

 Min., 1888, p. 250. 



Veyms ke7inerleyi Rye., Icon. Conch. ( Venus'), PI. XII, fig. 41 {^fide Gabb). 



"Shell large, thick, rounded, subquadrate, very inequilateral; beaks anterior; anterior end 

 excavated under the beaks, rounded below; base broadly rounded; posterior end convexly truncated; 

 cardinal margin slightly convex. Surface closely marked by numerous prominent, recurved, 

 lamelliform concentric ribs. Lunule marked by an impressed line. Hinge robust. Pallial line 

 strong, sinus small, oblique, acute at base; muscular scars nearly equal in size; margin minutely 

 crenulated; the purple color between the pallial line and the base is very persistent." — [Gabb.] 



Found in the Pliocene at Packard's Hill, and in the Pleistocene at the bath- 

 house, Santa Barbara. 



