ARNOLD — THE PALEONTOLOOY AND STRATir.R.VPHY OF SAN PEDRO. 333 



ribs, ami also near the posterior margin of whorl, are less prominent ridges; incremental lines visible; 

 body-wliorl angular, with nodose ridge on angle; base of this whorl nearly flat, and ornamented with 

 two prominent nodose spiral ridges and several lesser ones; umbilicus deep, but not very effuse; 

 aperture ovate; inner lip slightly overlapping umbilicus; suture not impressed, indistinct. 



Dimensions, — Alt. 6.5 mm.; lat. 6.5 mm.; body-whorl 5 mm.; aperture 3.5 mm.; defl. 

 75 degrees. 



This variety is (listini^ui.shiihle by its siiuple conical sliapc, Hat wliorls, and 

 nodose ridges. It may grade into the turl)inated, convex-wliorlcd variety, M. knechti, 

 although no mutations have been foiiiul in the large series at hand. This form was 

 pronounced a variety of 31. optahilis by Dr. Dall. 



Found in the lower San Pedro series of San Pedro and Deadman Island. 

 The specimen figured is the type, which is from the lower San Pedro series at San 

 Pedro, and is now in the United States National Museum. 



Pleistocene. — San Pedro (Arnold). 



388. Margarita parcipicta Carpenter, var. pedroana, var. nov. 



Pl.\te V, Fio. 16. 



Gibbida parcipicta CpR., Brit. Assn. Rept., 1863, p. 653; Ann. & Mag. Nat. Hist., 3rd Ser., 

 Vol. XIV, 1864, p. 427. 



Shell small, thin, globular, conical; spire elevated, subacute; whorls four, rounded, tabulated 

 near posterior margin; four spiral ridges on upper whorls; suture deeply impressed and distinct; 

 base of body-wiiorl rounded, and ornamented by fine s[)iral ridges; umbilicus deep and effuse; 

 aperture subcircular. 



Dimensions. — Alt. 5.5 mm.; lat. 5.5 mm.; body-whorl 4.5 mm.; aperture 3 mm.; defl. 

 80 degrees. 



Specimens pronounced variety of M. parcipicta by Dr. Dall. 



Found in the lower San Pedro series at Deadman Island and San Pedro; and 

 in the upper San Pedro series at Deadman Island, San Pedro, and Los Cerritos. 

 The specimen figured is the type, which is from the lower San Pedro series at Saa 

 Pedro, and is now in the United States National Museum. 



Pleistocene. — San Pedro (Arnold). 



389. Margarita pupilla Gould. 



Plate X, Fig. 15. 



Trochus pupillus Gld , Proc. Bost. Soc. Nat. Hist., Vol. Ill, 1850, p. 91; Wilkes' Expl. Exped., 



Vol. XII, p. 186, fig. 208, 1852. 

 Margarita pupilla Gld., = M. calostoma A. Ans. {^fidc Cpr., Brit. Assn. Rept., 1863, p. 653). 



= yJ/. salmonea Cpr. {Jide Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 249). 



Trvon, Man. Conch., Vol. XI, p. 295, PI. XLIV, figs. 29-32, 1889. Keep. West 



Coast Shells, p. 78, fig. 63, 1892. Williamson, Proc. U. S. Nat. Mus., Vol. XV, 



1892, p. 202. 



Shell small, ovate-conic, rather solid; whorls five, convex, flattened slighdy above, forming 

 a narrow, tabulate band just below suture; body-whorl obtusely angulated; surface sculptured with 



