162 CALIFORNIA ACADEMY OF SCIENCES. 



posterior end indented, the posterior extremity being much projected and sharply rounded; fold very 

 prominent; ligamental area short, scooped out. 



Diinenstons. — Long. 50 mm.; alt. 32 mm.; diam. 14 mm.; umbo to anterior exremity 

 28 mm. ; to posterior extremity 22 mm. 



Resembles M. nasitta and M. kcheiji, but is distinguishable by its smaller 

 shell, jwstei'ior umboiies, indentation in ventral margin, more prominent fold and 

 more prominently projected posterior extremity. Specimen identified by Dr. Dall. 



Rare in the upper San Pedro series at Los Cerritos and San Pedro. Found 

 in the Pleistocene at Spanish Bight, San Diego. The specimen figured is from the 

 upper San Pedro series at Los Cerritos, and is now in the collection of Delos Arnold. 



Living. — Monterey to San Diego (Cooper). 



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



Miocene. — El Toro Ranch, Monterey County; Griswold's, San Benito County 

 (Cooper). 



106. Macoma inquinata Dcshaycs. 



Plate XVI, Fu:. i. 



Tellina inquinata Desh., Proc. Zoo). Soc, 1854, p. 357. 



Macoma inquinata Desh., Carpenter, Brit. Assn. Rept., 1863, p. 689. Gabb, Pal. Cal., Vol. II, 

 p. 93, 1869. Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 248. Keep, West Coast 

 Shells, p. 195, 1892. Dall, Trans. Wagner Inst. Sci., Vol. Ill, Part 5, 1900, p. 1053. 



Shell of medium size, suboval, convex, thin, equivalve; umbones subcentral ; anterior end 

 dilated, rather prominently so in front of umbo of right valve; posterior end evenly arcuate from 

 umbo and acutely rounded at posterior end about half way between dorsal and ventral margins ; 

 ligament of medium length, not prominent; two small cardinal teeth in each valve; pallial sinus does 

 not reach anterior muscle-impression in the left valve. 



Di?ne>isio7ts. — Long. 35 mm.; alt. 27 mm.; diam. 15 mm.; umbo to anterior extremity 

 16 mm.; to posterior extremity 19 mm. 



Distinguishable by medium size, short, equally convex valves, very faint or 

 obsolete fold; evenly, acutely rounded, rather than truncated, posterior extremity, 

 and disconnection of pallial sinus and anterior muscle-impression. Specimen identi- 

 fied by Dr. Dall. 



Not uncommon in the Pliocene at Deadman Island, the lower San Pedro 

 series at Deadman Island, and the upper San Pedro series at Deadmnn Island, San 

 Pedro, Los Cerritos, and Crawfish George's. Found also in the Pleistocene at 

 Twenty-sixtli Street, San Diego. 



The specimen figured is from the upper San Pedro series at San Pedro, and 

 is now in the collection of Delos Arnold. 



Living. — Alaska to San Diego (Cooper). 



Pleistocene. — Monterey to San Diego (Cooper): San Pedro; San Diego 

 (Arnold). 



Pliocene. — Twelve Mile House; San Fernando (Cooper). 



