ARNOLD — Tin; PALEONTOLOGY AND STRATIGRAPHY OF SAN PEDRO. 339 



397. Fissuridea murina {Carpenter) Ball. 



Glypliis densiclalhtata var. murina Ci'K., niss. 



Fissuridce imirina (Cpr.) Dall, Proc. U. S. Nat. Mus., Vol. VIII, 1SS5, p. 543; Vol. XV, 1892. 



p, 197. 

 Glyphis densiclathrata Rvi:., Tryon, Man. Conch., Vol. XII, p. 215, \'\. XXXIX, fig. 81, i89o(pars). 



Cooper, Bull. No. 4, Cal. St. Min. Bureau, Part 3, 1894, p. 27. 



Shell resembles F. aspera in general outline; apical hole nearly central, circular; radiating 

 riilges numerous and smooth, except for fine incremental lines; inner margin of shell quite evenly 

 crcnulaled; color white. 



Dimensions. — Long. 46 mm.; hit. 30 mm.; alt. 16 mm. 



Distinguishable frotn /*'. aspera by lack of coloration, finer and more numer- 

 ous ribs, more central and more nearly round apical hole. Smaller than the latter. 

 Dr. Dall says that this is the same species which Californian conchologists have been 

 calling Gbjplds densiclathrata, hut that it is not the same as Reeve's G. densiclathrata. 



Four specimens in the upper San Pedro series of San Pedro; found in the 

 saujo horizon at Deadman Island, Los Cerritos, and Crawfish George's; ami in the 

 lower San Pedro series at Deadman Island. 



Living. — San Pedro; Catalina (Williamson): Santa Barbara (Cooper). 



Pleistocene. —San Pedro (Arnold) : San Joaquin Hay, Orange County (Bowers). 



Genus Clypidella Sivainson. 



Shell oval, rugose, slightly elevated, truncated at the anterior extremity; perforation large, 

 subcentral, or somewhat anterior, 



Clypidella pustulata Lam. is a characteristic species. 



398. Clypidella bimaculata Dull. 



Clypidella (?) bimaculata Uall, mss., in Cooper, Geol. Cat. W. C. Shells, No. 470, 1866. 

 Fissurellid(sa bimaculata Dall, Am. Jour. Conch., Vol. VII, 1872, p. 132, PI. XV, fig. VII. 



Keep, West Coast Shells, p. 97, fig. 82, 1892. 

 Clypidella bimaculata Dall, Gabb, Pal. Cal., Vol. II, pp. 86, 124, 1869. Cooper, 7th Ann. Rept. 



Cal. St. Min., 1888, p. 235. 

 Megatebennus bimaculatus Dall, Trvon, Man. Conch., Vol. XII, p. 183, PI. XLIV, fig. 94, 1890. 



Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 198. 



Shell resembles C. callomarginala. Aperture and apical hole elliptical, the latter being 

 central; wide, thickened ridge on inner side of rim and on inner side of apical hole. Smaller than 

 C. callomarginala. 



Specimens identified by Dr. Dall. 



Not uncommon in the lower San Pedro series of Deadman Island and San 

 Pedro; rare in the upper San Pedro series of Los Cerritos and San Pedro. 



Living. — Farallon Islands to Santa Barbara Islands (Cooper). 



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



