AKNOLD — THE PALEONTOLOGY AND STRATIGRAPHY OF SAN PEDRO. 129 



Sliell small, subcircular, VL-ntricose, thick ; unibones slightly anterior to center, much bent 

 forward, prominent; surface sculptured by about thirteen prominent, rounded, radiating ridges, 

 which are slightly roughened by regular lines of growth; sulcations narrow; hinge area broad, short; 

 two prominent teeth in each valve, anterior short; margin clcjsely crenulated. 



Dimensions. — Long. 12.5 mm.; alt. 13 mm.; (li.im. ,S mm. 



Distinguisliahio by small size, coarse scul])tiire and heavy liinge. Common in 

 tlie Pliocene of Deadman L'sland and Timm's Point; tare in lower San Pedro series 

 of Deadman Lsland. Found also in Pleistocene of Pacific Beach, near 8an Dief^o; 

 and in the Pliocene of Packard's Hill and the Pleistocene near the bath-house, 

 Santa Barbara. 



Living. — Alaska to Catalina Island (Cooper). 



Pleistocene. — Santa Barl)ara to San Diego (Cooper): San Pedro; Santa Bar- 

 bara; San Diego (Arnold). 



Pliocene. — San Fernando; Santa Barbara to San Diego (Cooper): San Pedro; 

 Santa Barbara (Arnold). 



Miocene. — Oregon; Foxin's, Santa Barbara County; Santa Monica (Coo2)er): 

 Blakeley, near Seattle, Washington (Arnohl). 



Genus Lazaria Conrad. 



Shell transverse, oblong, inequilateral; beaks subanterior, radiately ribbed ; hinge with two 

 cardinal and two lateral diverging teeth in each valve, the posterior teeth being in each case much 

 elongated, the anterior short and more or less pointed, sublunular. 



Lazaria pectunculus Brng. is a characteristic S2:)ecies. 



56. Lazaria subquadrata Carpenter. 



Lazaria subquadrata Cpr., Brit. Assn. Rept., 1863, p. 642; Ann. Mag. Nat. Hist., 3d ser. , Vol. XV, 

 1865, ]). 179. Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 244. Keep, West Coast 

 Shells, p. 179, fig. 152, 1892. Williamson, Proc. U. S. Nat. Mus.,Vol. XV, 1892, p. 190. 



Shell small, transverse, subrectangular, inequilateral, ventricose, thick; beaks subanterior, 

 not prominent ; dorsal posterior margin long, straight ; anterior portion abruptly truncated just in 

 front of beak; surface sculptured with heavy, squamose, rounded, radiating ridges; interior 

 margin coarsely crenulated; hinge with two lateral diverging teeth in each valve, the posterior teeth 

 being in each case much elongated, the anterior short and pointed. 



Dimensions. — Long. 10 mm.; alt. 6 mm.; diain. 5 6 mm. 



Distingnishable by its small size, rectangidar outline, and coarse, squamose 

 ridges which radiate from one corner of the rectangle. 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 Crawfish George's and San Pedro. 



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



Pleistocene. — Santa Barbara (Coojier): San Pedro (Arnold). 



( 17 ) December 29, 1902. 



