100 CALIFORNIA ACADEMY OF SCIENCES. 



occurs on the posterior margin; surface sculptured concentrically as in }'. cooperi except that this 

 incised sculpture is not in harmony with the incremental lines; hinge and teeth similar to Y. cooperi. 

 Dime7isio7is.- — Long. 20.4 mm.; alt. 10 mm.; diam. 4 mm. ; from umbo to anteriorend 9 mm. ; 

 to posterior end 12 mm. 



This delicate little shell resembles Y. cooptri \\\ many respects, but is easily 

 distinguishable by its smaller size, more delicate shell, the peculiar way in which the 

 sculpture crosses the incremental lines, and by its relatively broader anterior end. 

 Probably the Y. amygdala Yal. reported by Cooper (7tli Ann. Rept. Cal. St. Min., 

 1888, p. 270) as occurring at Deadman Island is Y. scissurata Dall. Specimens 

 identified by Dr. Dall. 



Three specimens from lower San Pedro series of Deadman Island; lare. 

 Specimens of Y. scissurata in the State Museum collection of fossils at Berkeley are 

 labeled Y. amygdnla. The specimen figured is from the lower San Pedro series at 

 Deadman Island, and is now in the collection of Delos Arnold. 



Living. — Puget Sound (Carpenter). 

 Pleistocene. — San Pedro (Arnold. 



Superfamily ARCACEA. 



Family VII. ARCID.E. 



Subfamily PECTUNCULlNyE. 



Genus Glycy maris Da Costa. 



Shell orbicular, nearly equilateral, smooth or radiately striated; umbones central, divided by 

 a striated ligamental area; hinge with a semicircular row of transverse teeth; adductors subequal; 

 pallial line simple; margins crenated inside. 



Type, Area glycymeris Linn. 



19. Glycymeris barbarensis Conrad. 



Plate XVIII, Fic. 9. 



Axi7tea barbarensis Con., Pac. R. R. Rept., Vol. VI, 1857, p. 71, PI. Ill, fig. 11; Vol. VII, 1S57, p. 



194, PI. VI, fig. 3. 

 Axinea intermedia (not of Brod. ; not of Carpenter, Brit. Assn. Rept., i86j, p. 644), of Cooper, 



in part, 7th Ann. Rept. Cal. St. Min., 1888, p. 230 (not of Keep, West Coast Shells, 1892, 



p. 169; not of Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 192; not of Dall, 



Trans. Wagner Inst. Sci., Vol. Ill, Part 4, 1898, p. 608. 



Shell of medium size, convex, thick, subcircular, with angular aspect at umbones caused by 

 the anterior dorsal margin being nearly straight; posterior end rounded; anterior end angular; sur- 

 face area between umbones and interior as in G. septentrionalis. 



Dimensions. — Long. 33.3 mm.; alt. 32 mm.; diam. 22 mm. 



Distinguishable from 0. septentrionaliii. by wider, more trigonal shell and angular 



