ABNOLD — THE PALEONTOLOGY AND STRATIORAPHY OF SAN rEDRO. 333 



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

 body-whorl 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 nim.; lat. 6.5 mm.; body-whorl 5 mm.; aperture 3.5 mm.; dcfl. 

 75 degrees. 



This variety is distinmiishable by its simple conical shape, flat whorls, and 

 nodose ridges. It may grade into the turbinated, convex-wliorled variety, M. knechti, 

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

 pronounced a variety of -1/. optabiiis by Dr. Dall. 



Found in the lower San Pedro series of San Pedro and Deaduian 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. 



Plate V, Fio. 16. 



Gibbula 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-whorl rounded, and ornamented by fine spiral 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 San 

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



Pleistocene. — San Pedro (Arnold). 



389. Margarita pupilla Gould. 



Plate X, Fio. )5. 



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



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

 Margarita pupilla Gld., = M. calostoma A. Ads. (^fide Cpr., Brit. Assn. Rept., 1863, p. 653). 



= M. salmonea Cpk. {^fide 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 vShells, 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 slightly above, forming 

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



