ARNOLD — THE PALEONTOLOGY AND STRATIORAPHY OF SAN PEDRO. 173 



This sjiccies is distinguisliablc from var. miHoUi h_y its small sizo, fragile shell, 

 more posterior umbo, aiul sharper, narrower, siiorter, and more nearly perpendicular 

 interior callus. Dr. Dall in his paper on the Solenidse says that Carpenter (Brit. 

 Assn. Rept., 1808, p. ()34) and Gabb (186S) have confounded tlie young of S. nutialH 

 with this species. A large series of S. Iticida from the Pleistocene shows the above 

 mentioned differentiating characteristics to be constant. Specimens identified 

 by Dr. Dall. 



Kather rare in the lower San Pedro series at Deadman Island and San Pedro; 

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

 Pleistocene at Twenty-sixth Street and Spanish Bight, San Diego. 



Living. — Monterey to San Diego (Dall). 



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



123. Siliqua patula (Dixon) var. nuttalli Conrad. 



Soleatrtiis w?^//a/// Con. , Jour. Phil. Acad. Sci. , Vol. \'II, 1S37, page 232, PI. XVII, fig. 9. 



Mac har a patula, not of Dixon, Voy. Around the World, p. 335, fig. 2, 1789. Carpenter, Brit. 



Assn. Rept., 1863, p. 638 (in part). Gabb, Pal. Cal., Vol. II, p. 89, 1869 (in part). 



Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 248 (in pari). ? Keep, West Coast 



Shells, p. 201, fig. 171, 1892. 

 ? Siliqua patula DixoN, Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 185. 

 Siliqua nuttalli Coti., ^= S. califoniica CoN. (yfide Dall, Trans. Wagner Inst. Sci., Vol. Ill, Part 5, 



1900, p. 956). 



Shell large, oblong-oval, compressed, thin, fragile; umbones a little over one-fourth length 

 from posterior end, minute; anterior end more acutely rounded than posterior; ligamental area 

 prominent, projecting beyond an equally long depression in the anterior dorsal margin; cardinal 

 teeth in right valve, four in the left; a strong, elevated callus extends over half way across the in- 

 terior of the shell from the umbo at nearly right angles with the dorsal margin. 



Dimensions. — Long. loi mm.; alt. 39 mm.; diam. 14 mm. 



Distinguishable from B. lucida by larger, heavier shell; distinguished from 

 Tagelus californianus by the posterior position of the beaks, and by the more rounded 

 extremities. Specimens identified by Dr. Dall. 



Rare; a nearly perfect pair from the upper San Pedro .series at San Pedro. 

 Found also in the Pleistocene at Spanish Bight, San Diego. 



Living. — Mouth of the Columbia River (Conrad). 



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



Pliocene. — ? Localities. 



Miocene.— 1 Localities. 



