ARNOLD — THK PALEONTOLOGY AND STRATIGRAPHY OF SAN PEDRO. 339 



397. Fissuridea murina {Carpenter) Dull. 



Glyphis densiclathrata var. murina Cpr., mss. 



Fissiirida murina (CpR.) Dall, Proc. U. S. Nat. Mus., Vol. VIII, 1885, p. 543; Vol. XV, 1892, 



p. 197. 

 Glyphis densiclathrata 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. aspera in general outline; apical hole nearly central, circular; radiating- 

 ridges numerous and smooth, except for tine incremental lines; inner margin of shell quite evenly 

 crenulated; color white. 



Dimensioiu. — Long. 46 mm.; lat. 30 mm.; alt. i6 mm. 



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

 ous ribs, more central and more nearly round apical bole. Smaller tban tbe latter. 

 Dr. Dall says tbat tliis is tbe same species wbicb Californiau concbologists bave been 

 calling Glijphis densiclathrata, but tbat it is not tbe same as Reeve's Q. densiclathrata. 



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

 same borizon at Deadman Island, Los Cerritos, and Crawfisb George's; and in tbe 

 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 Swainson. 



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

 subcentral, or somewhat anterior, 



Clypidella pustulata Lam. is a cbaracteristic species. 



398. Clypidella bimaculata Dall. 



Clypidella (f) bimaculata Dall, ms.s. , in Cooper, Geol. Cat. W. C. Shells, No. 470, 1866. 

 Fissurellidaa 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. Sl 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. callomargitiata. 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 tbe lower San Pedro series of Deadman Island and San 

 Pedro; rare in tbe 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). 



