AKNOLD-THK PALEONTOLOCi Y AND STRATIGIJAI'UY OF SAN PEDllO. 151 



Pliocene. — Siuita Uusii; Twelve Mile lluu-se, San Mateo County; Kirker's 

 Pass, Contra Costa County; Monterey; San Fernando (Cooper); San Diego (Arnold). 

 Miocene. — West of San Jose; Foxin's, Santa Barbara County (Cooper). 



89. Tapes tenerrima Carpenter. 



I'l.AiK XIV, Fio. 6. 



Tapes tenerrima Cpu., Proc. Zool. Soc, 1856, p. 200; (jun.) ^=Vciuis rigida Gld., pars. (y?</^ 



Cari^enter, Brit. Assn. Rept., 1863, p. 641.) Gabb, Pal. Cal., Vol. II, p. 97, 1869. 



Cooper, yth Ann. Rept. Cal. St. Min., 1888, p. 267. Keep, West Coast Shells, 



P- '57. fiy:. '36, 1892. Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 188. 



Shell larije and thin, oval, convex; surface sculptured by numerous low, sharp, concentric 



frills, and numerous fme, rounded, crowded, radiating; lines, these latter lines being almost obsolete 



in some specimens; margin smooth, hinge long and narrow; three teeth in each valve, the anterior 



two in the right valve and the middle one in the left valve prominently bifid; pallial sinus very deep 



and rounded; no lunule. 



Dimensions. — Long. 86 mm.; alt. 63.5 mm.; diam. 34 mm. 



This is the largest and linest 7'apes found in these deposits, and is easily 

 distinguishable by its large, thin, shallow shell and regular, oval outline. Specimens 

 identified by Dr. Dall. 



Kather rare in the upper San Pedro serie.s of San Pedro, Los Cerrito.s, Crawfish 

 George's and Deadiiian Island. The specimen figured is from the upper San Pedro 

 series at San Pedro, and is now in the collection of Delos Arnold. Found also in the 

 Pleistocene at Barlow's ranch, Ventura, and at Spanish Bight, San Diego. 



Living. — Straits of Fuca to San Diego (Cooper). 



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

 (Arnold). 



Pliocene. — Santa Barbara (Coo]ier). 



Genus Saxidomus Conrad. 



Shell transversely oval, inequilateral, solid, ventricose; without lunule; umbones tumid; 

 teeth three or four, inequal, narrow, the central bifid; ligament very thick, elongated; muscular 

 impressions oval or rounded, nearly eciual; p.dlial sinus large, elongated, horizontal. 



Type, Saxidomus mittnllii (Con.). 



90. Saxidomus aratus Gould. 



Saxidomus aralus Old., Otia Conch., p. 168, 1862. Carpenter, Brit. Assn. Rept., 1863, p. 641. 



Keep, West Coast Shells, p. 183, 1892. Williamson, Proc. U. S. Nat. Mus., Vol. 



XV, 1892, p. 188. 

 Taf>es gracilis Gld., Pac. R. R. Rept., Vol. V., p. 333, PI. XIX, fig. 20, 1853. 

 Saxidomus gracilis, Gld., ^=Vetius maxima Phil. {Jide Gabb, Pal. Cal., Vol. II, 1869, p. 98). 



Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 263. 



