ARNOLD — THE PALEONTOLOGY AND STUATIGKAPHY OF SAN PEDUO. "10 



Shell conical, apex erect, nearly central, rather sharp, smooth; posterior surface straight; 

 anterior slightly convex; ornamentation of fine incremental lines, giving (juite a rough surlace to 

 some specimens; aperture oval to nearly circular; rim smooth. 



Dimensions. — Long. 31 mm.; lat. 27.5 mm.; alt. 19 mm. 



Easil}' distingui.sliable by its elevated, nearly central apex, comparatively 

 smooth, light colored surface, and its size. 



Not uncommon in the upper San Pedro series of Crawfish George's. 



Living. — Sitka to San Diego (Cooper): Half Moon Bay, San Mateo County 

 (Arnold). 



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



362. Acmaea paleacea Gould. 



Acmcea paleacea Gld., Bost. Jour. Nat. Hist., Vol. VI, 1853, P- 376. PI XI\^ fig. 5; Mex. and C:il. 



Shells, p. 3, PI. XIV, fig. 5, 1853. Dall, Am. Jour. Conch., Vol. VI, i87i,p. 253. 



Tryon, Man. Conch., Vol. XIII, p. 20, PI. VI, fig. 42, 1891. Williamson, Proc. U. S. 



Nat. Mus., Vol. XV, 1892, p. 197. 

 Nacella paleacea Gld., Cpr., Brit. Assn. Rept., 1863, p. 650. Keep, West Coast Shells, p. 104, 1892. 



"Shell minute, delicate, thin, elongated, laterally compressed, so that the two sides are 

 parallel; dorsal aspect a long, narrow oval; lateral aspect low, triangular; apex at about the anterior 

 third, acute, antrorse; surface with delicate lines of growth and a few obtuse radiating ridges along 

 the dorsal slope at each end; color cinnamon brown." 



Dimensions. — Long. 7 mm.; lat. 1.5 mm.; alt. 2 mm. 



This shell has little resemblance to any of the others of its genus iound in tlii.s 

 formation, and may readily be distinguished by its small size and peculiar shape. 

 Dr. Dall identified the specimen. 



Rare in the upper San Pedro series of Crawfish George's; two specimens found. 



Living. — Santa Barbara (Jewett): Monterey; San Diego (Dall). 

 Pleistocene. — San Pedro (Arnold). 



363. Acmsea pelta Eschscholtz. 



Acmaa pelta EscH., Zool. Atl., Vol. V, p. 19, No. 5, 1833. Cpr., Brit. Assn. Rept., 1863, p. 650. 

 Gabb, Pal. Cal., Vol. II, p. 52, 1869. Dall, Am. Jour. Conch., Vol. VI, 1871, 

 p. 246, PI. XIV, fig. 6. Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 228. Tryon, 

 Man. Conch., Vol. XIII, p. 17, Pi. VIII, figs. 86-95, 1891. Keep, West Coast Shells, 

 p. 102, 1892. Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 197. 



Shell depressed, rounded, with few prominent bulging ribs, which are not developed in the 

 yoving shell; ape.\ smooth, obtuse, and anterior to center. 



Two specimens sent to Dr. Dall were identified by him as the young of 

 this species. 



Rare in the lower San Pedro series of Deadman Island; and upper San Pedro 

 series of Los Cerritos and San Pedro. Found in the Pleistocene at Pacific Beach, 

 San Diego; and at Barlow's ranch, Ventura. 



