ARNOLD— THE PALEONTOLOGY AND STRATIGKAPHY OP SAN' l>KI)UO. ISl 



133. Corbula luteola C<ir/)enter. 



Pl,ATK XVII, FlC. II. 



Corbida lutcola Cpr., Brit. Assn. Rept., 1S63, p. 637. Cooper, ytli Ann. Rept. Cal. St. Min., 1888. 

 p. 236. Keep, West Coast Shells, p. 204, 1892. Williamson, Proc. U. S. Nat. 

 Mus., Vol. XV, 1892, p. 183. Dai.l, Trans. Wagner Inst. Sci., Vol. Ill, Part IV, 

 1898, p. S56. 



Shell .small, snbelliptical, jiibbose, thick; beaks, subcentral, small, inconspicuous; anterior 

 extremity evenly rounded; posterior dorsal margin slightly arcuate, .sloping down nearly to base, 

 where it turns abruptly, forming an angular e.\tremit)': ventral margin arcuate; a sharp sub- 

 marginal ridge extends from beak to lower portion of jjosterior extremity; surface sculptured with 

 line, but distinct, concentric ridges; right valve with one prominent cardinal tooth in front of 

 cartilage-pit; left valve smaller, with a projecting cartilage process; pallial sinus slight; pedal scar 

 distinct from adductor impressions. 



Dimensions. — Long. 8 mm.; alt. 5.5 mm.; diam. 3.5 mm. 



Tliis species i.s distinguishable by its peculiar shape, the sharp posterior, sub- 

 inir:;iiial ridge, and the delicate sculpture. Specimens identilied by Dr. Dall. 



Found in the Pliocene at Deadman Island; in the lower San Pedro series 

 at Dcadinan Island and San Pedro; and in the upper San Pedro series at San Pedro 

 and Los Cerritos. Also found in the Pleistocene at Twenty-sixth Street, San Diego. 



The specimen figured is from the lower San Pedro series at Deadinaii Island, 

 and is now in the collection of Delos Arnold. 



Living. — San Pedro to San Diego (Cooper). 



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



Pliocene. — San Pedro (Arnold). 



Genus Neaera Gray. 



Shell globular, attenuated, and gaping posteriorly; right valve a little the smallest; umbone 

 strcngiliened internally by a rib on the posterior side; cartilage-process spatulate, in each valve, with 

 an obsolete tooth in front, and a posterior lateral tooth; pallial sinus very shallow. 



Necera ornatissima Irb. is a characteristic species. 



134. Nesera pectinata Carpenter. 

 Pl.vte XVIII, Fui. 11. 

 Neara pectinata Cpr., Brit. Assn. Rept., p. 637, 1863. 



Shell small, globular, attenuated and gaping behind, thin; umbones anterior; dorsal line 

 straight; anterior extremity evenly rounded; posterior extremity drawn out to a very long, narrow, 

 truncated beak; ventral margin greatly arcuate; surface sculptured by twelve prominent, sharp, 

 radiating ridges; posterior elongation smooth; cartilage-process spatulate, with an obsolete tooth 

 in front. 



Dimensions. — Long. 6.5 mm.; alt. 3.4 mm,; diam. 2.3 mm.; umbo to anterior extremity 

 2.5 mm.; to posterior extremity 4 mm. 



This unique little shell is distinguishable by its |)rominent radiating sculpture 

 and wing-like posterior projection. Specimen identified by Dr. Dall. 



