ARNOLD— THE PALEONTOLOGY AND STUATIGRAPHY OF SAM PEDRO. ISl 



133. Corbula luteola ('iir/>cntcr. 



Pi.ATK XVII, Fn;. II. 



Corbnla luleola Cpr., Brit. Assn. Rept., 1863, p. 637. Coopkr, 7th Ann. Rept. Cal. St. Min., i888> 

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

 Mus., Vol. XV. 1892, p. 183. Dall, Ti-ans. Wagner Inst. Sci., Vol. Ill, Part IV, 

 1898, p. S56. 



Shell small, subelliptical, gibbose, 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 extremity; ventral margin arcuate; a sharp sub- 

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

 fine, 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. 



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



Tliis species is distinguishable by its peculiar shape, the sharp posterior, sub- 

 rairgiual ridge, and the delicate sculpture. Specimens identified b}'^ Dr. Dall. 



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

 at Deadinan Island and San Pedro; and in the upper Sau 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 Deadinan Island, 

 and i.-^ now in the collection of Delos Arnold. 



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



Pleistocene. — 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 

 strengthened 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. Neaera pectinata Carpenter. 



PI.ATK XVIII, Fig. 11. 

 Ne^sra 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 prominent radiating sculpture 

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



