ARNOLD— THE PALEONTOLOGY AND STRATIGRAPHY OF SAN PEDRO. 117 



" Shell adherent, subequivalve, irregular, flattened ; hinge with two thick, divergent, elongated 

 lamella in the inferior, corresponding with two long pits in the upper valve; upper valve with only 

 two muscular impressions; the pedal scar radiately striated"; surface with incremental laminse and 

 sometimes radial ridges. 



Part of the above description was taken from Tryon. This species resembles 

 Anomin lampe, but may be distinguished by its greater size and fewer muscle-impres- 

 sions. Specimen identified by Dr. Dall. 



Rare in the upper San Pedro series of San Pedro, Crawfish George's, and 

 Deadman Island. Found also in the Pleistocene of the bluff west of the bath-house, 

 at Santa Barbara. 



Living. — Unalaska to San Diego; Japan (Cooper). 



Pleistocene. — Santa Barbara to San Diego (Cooper): San Pedro (Arnold): 

 California; Oregon; Alaska (Dall): Santa Barbara (Arnold). 



Pliocene. — San Diego well (Dall)^ 



2Iiocene. — Sooke, Vancouver Island (Newcombe). 



Genus Anomia Linne. 



Shell suborbicular, translucent, attached by a plug passing through a hole or notch in the 

 right valve ; upper valve convex, smooth, lamellar, or striated ; two byssal scars on the disk, main 

 byssal scar largest; foramen open, ample; hinge unarmed. 



Anomia ejyhijjpium Linne is a characteristic species. 



39. Anomia lampe Gray. 



Anomia lampe Gray, Proc. Zool. Soc, 1849, p. 114. Carpenter, Brit. Assn. Rept., 1863, p. 646. 

 Gabb, Pal. Cal, Vol. II, 1S69, p. 106. Cooper, 7th Ann. Rept. Cal. St. Min., 18S8, 

 p. 229. Keep, West Coast Shells, p. 163, 1892. Williamson, Proc. U. S. Nat. Mus., 

 Vol. XV, 1892, p. 194. Dall, Trans. Wagner Inst. Sci., Vol. Ill, Part 4, 1898, p. 785. 



Shell of medium size, suborbicular, thin, translucent and slightly pearly within; surface of 

 left valve sculptured with fine, irregular, concentric lamellar lines and several prominent, irregular, 

 rounded, radiating ridges; interior of this valve with submarginal cartilage pit and four muscular 

 impressions; right or lower valve concave, with a deep rounded notch in front of the cartilage process. 



Dimensions. — Long, and alt. 48 mm.; diam. 9 mm. 



This species is variable both in regard to its shape and its sculpture, but is 

 easily distinguisliable by the thin, lamellar, translucent shell. Distinguishable from 

 A. limatula Dall by its smaller size and radial ridges. Specimens identified by 

 Dr. Dall. 



Common in the upper San Pedro series of San Pedro, Los Cerritos, Long 

 Beach, and Crawfish George's; rare in the lower San Pedro series of Deadman Island 



