ARNOLD — THE PALEONTOLOCiV AND STUATIliliAl'UY OV SAN PEDUO. 151 



Pliocene. — Santa Rosa; Twelve Mile House, San Mateo County; Kirkor's 

 Pass, Contra Costa County; Monterey; San Fernanilo (Cooper) ; San Diego (Arnokl). 

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



89. Tapes tenerrima Carpenter. 



Plate XIV, Fio. 6. 



Tafies tenerrima Ci'R., Proc. Zool. Soc, 1S56, p. 200; (jun.) —Venus ri^^ida G:,D., [lars. {fide 



Carpenter, Brit. Assn. Rept., 1863, p. 641.) Gabb, Pal. Cal., Vol. II, p. 97, iS6y. 



Cooper, 7th Ann. Rept. Cal. St. Min., 1S88, p. 267. Keep, West Coast Shells, 



P- 157. fig. 136, 1892. Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 188. 



Shell large and thin, oval, conve.x; surface sculptured by numerous low, sharp, concentric 



frills, and numerous fine, 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 biful; pallial sinus very deep 



and rounded; no lunule. 



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



This is the largest and finest I'apes t'omul in these deposits, and is easily 

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

 identified by Dr. Dall. 



Rather rare in the upper San Pedro series of San Pedro, I>os Cerritos, Crawfish 

 George's and Deaduiau Island. The specimen figured is from the upper San I'edro 

 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 Sau Diego (Cooper). 



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

 (Arnold). 



Pliocene. — Satita Barbara (Cooper). 



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 equal; pallial sinus large, elongated, horizontal. 



Type, Saxidomus nuttallii (Con.). 



90. Saxidomus aratus Gould. 



Saxidomus aratus Gld., Otia Conch., p. 168, 1862. Carpenter, Brit. Assn. Rept., 1S63, \>. 641. 



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



XV, 1892, p. 188. 

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

 Saxidomus gracilis, Gld., = Venus maxima Phil. (yf</<? Gabb, Pal. Cal., Vol. II, 1869, p. 98). 



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



