ARNOLD— THE PALEONTOLOGY AND STRATIGRAPHY OF SAN PEDRO. 141 



74. Cardium (Laevicardium) elatum Sowcrby. 



Plate XX. 



Cardium e/atum S^\'., Conch III, Vol. I, 1838. Reeve, Conch. Icon., PI. VIII, fig- 41. Valen- 

 ciennes, Voy. Venus, PI. XVII, fig. r, 1846. 



Liocardium elatum Sby., Carpenter, Brit. Assn. Rept. , 1863, p. 642. Cooper, 7th Ann. Rept. Cal. 

 St. Min., 1888, p. 246. Keep, West Coast Shells, p. 181, 1892. Williamson, Proc. 

 U. S. Nat. Mus., Vol. XV, 1892, p. 190. 



Lcsvicardium elatum Sby., Gabb, Pal. Cal., Vol. II, p. 99, 1869. Dall, Trans. Wagner Inst. 

 Sci., Vol. Ill, Part 5, 1900, p. 11 11. 



Shell large, oval, oblique, elongated, equivalve, somewhat inequilateral ; surface sculptured 

 by numerous faint, squarish, radiating ribs, and fine, wavy incremental lines; inner surface of margin 

 corrugated ; hinge strong, with one prominent cardinal and one prominent anterior lateral tooth in 

 each valve ; muscle-impressions distinct. 



Dimeyisions. — Long. 144 mm.; alt. 167 mm.; diam. 136 mm. 



This is the largest of the Gardiidm, and is easily recognizable by its immense 

 size and nearly smooth surface. A tine pair of this species, described above, and 

 figured, was found in the upper San Pedro series at the north end of the San Pedro 

 bluflf. Another specimen was obtained by Dr. A. A. Wright and Mrs. Oldroyd in 

 tlie upper San Pedro deposits of Los Cerritos. This species is one of the typical 

 southern forms found in the upper San Pedro series. 



Living. — San Pedro to Mazatlan (Cooper). 



Pleistocene. — San Pedro (Cooper; Arnold): San Diego (Gabb; Dall). 



75. Cardium (Laevicardium) substriatum Conrad. 



Cardium substriatum Con., Jour. Phil. Acad. Sci , Vol. VII, 1837, p. 228, PI. XVII, fig. 2. 

 Liocardium substriatum Coti , ^= cruentatum Gould, {Jide Carpenter, Brit. Assn. Rept., 1863, 



p. 642.) Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 246. Keep, West Coast 



Shells, p. 181, fig. 154, 1892. Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, 



p. 190. 

 Lcsvicardium substriatum Con., Gabb, Pal. Cal., Vol. II, p. 99, 1869. Dall, Trans. Wagner Inst. 



Sci., Vol. Ill, Part 5, 1900, page mi. 



Shell small, obliquely ovate, ventricose, thin ; surface smooth, except for minute incre- 

 mental lines and nearly obsolete radiating striae ; one small sharp cardinal tooth in each valve ; two 

 narrow elongated lateral teeth in each valve, the posterior one in the left valve not prominent ; 

 interior of margin finely crenulated. 



Dimensions. — Long. 17 mm.; alt. 18 mm.; diam. 13 mm. 



Distinguishable by its small size and smooth surface. Specimens identified 

 by Dr. Dall. 



Rare in the lower San Pedro series of Deadman Island and San Pedro, and 

 in the upper San Pedro series of Deadman Island, San Pedro, Crawfish George's, 

 and Los Cerritos. Found also in the Pleistocene at Twent3r-sixth Street, San Diego. 



Living. — Monterey to South America (Cooper). 



Pleistocene. — Santa Barbara; San Pedro; San Diego (Cooper): San Pedro 

 (Arnold): San Diego (Arnold). 



