ARNOLD — THE PALEONTOLOGY AND STEATIGEAPHY OF SAN PEDRO. 339 



397. Fissuridea murina {Carpenter) Dall. 



G typhis dcnsiclalhraia var. imiritta Cpr., mss. 



Fissurida: murma (Cpr.) Dall, Proc. U. S. Nat. Mus., Vol. VIII, 1885, p. 543; Vol. XV, 1892, 



p. 197. 

 Glyphis deyisiclathrata RvE., Tryon, Man. Conch., Vol. XII, p. 215, PI. XXXIX, fig. 81, 1890 (pars). 



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



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

 ridge.s numerous and smooth, e.xcept for line incremental lines; inner margin of shell quite evenly 

 crenulated; color white. 



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



Distinguishable from F. aspera by lack of coloration, finer and more numer- 

 ous ribs, more central ;ui(l more nearly roniul apical hole. Smaller than tlie latter. 

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

 calling Glijphis densiclnthrafa,hut that it is not the same as Reeve's G. dent^idnthratd. 



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

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

 lower San Pedro series at Deadman Island. 



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



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



Genus Clypidella Sivainson. 



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

 subcentral, or somewhat anterior, 



Clypidella pustnlata Lam. is a characteristic species. 



398. Clypidella bimaculata Bull. 



Clypidella (f) bimaculala Dall, mss., in CooPER, Geol. Cat. W. C. Shells, No. 470, 1866. 

 Fissurellidiea 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., 1S88, p. 235. 

 Megatebeniius bimaculatus Dall, Tryon, Man. Conch., Vol. Xll, p. 183, PI. XLIV, fig. 94, 1890. 



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



Shell resembles C. callomarginaia. 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. callomarginata. 



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). 



