;J22 CALirouMA ai'adkmy of sciences. 



Slicll <>l inoileratf size, conical; spire elL-vaicd, suljaculc; whorls tivc or six, llal, wiili luinnr- 

 oiis oblique, rounded, irregular, transverse ridges, with smaller ridges intercalated on luwcr pan ol 

 w hurls; siiliiri' inipifsst'd, wavy, distinct; apirture siihovatc; umbilicus obsolete; base tl.il, oi ii,uiuiilt(l 

 with several prominent, rounded, rugose spiral ritiges with squamose liruke between. 



Dimensions. — Alt. 23 mm.; hit. 25 nun.; dell. 65 nun. 



Tlii.s species resembles Pomnnln.v undosits (|iiiic c!lo.seIy, htit may he (listiiigiiisluMl 

 from tli;it species by l;iek of |ii(imincnt keel on ;iiiU'riiir niainiii of wliorl, iiilercalated 

 transverse ridges, arid |>rnmiMoiil spiral ridj^cs on base. 



Kare in upper San Pedro scries of S;ni Pedro. 



J/iriiiff. — Straits of Fiiea to < ':it;ilin:i Island (('unpcr). 



P/ehiocene. — Santa Barbara; San I'cdro (Coupcr): San I'udro (Williamson; 

 ArnoUl). 



Genus Pomaulax druij. 



Shell trochiform, elevated, conic, aiigulated and nodose at the periphery; oliliquely ribbed; 

 not unibilicated; inner lij) arcuated witli a wiile callus, which is channeled, anteriorly tiinicated. 



Type, Pomaulax undosus Wood. 



367. Pomaulax undosus Wiwd. 



Trochus undosus Wood, Index, Test. Suppi., PI. LI, fig. i, 1S28; Suppl., j). 16, PI. \', tig. i, 1S59. 

 Pomaulax undosus Wood, Cpr., Brit. Assn. Rept., 1863, p. 651. Gabb, Pal. Cal., Vol. II, p. 83, 



1869. Trvon, Man. Conch., Vol. X, p. 243, PI. LVIII, figs. 69, 70, 1S88; Syst. and 



Struct. Conch., Vol. II, p. 308, PI. LXXX, fig. 33, 1S83. Cooper, 7th Ann. Rept. Cal. 



St. Min., 1888, p. 260. Keep, West Coast Shells, j). 89, fig. 75, 1892. WilllviMSOn, 



Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 199. 



Shell large, conical; spire elevated, subacute; whorls six or seven, flat with undulating, 

 nodose keel on anterior margin; transverse ridges on upper part of whorl, with sin. ill nodes near 

 middle of shell and toward anterior margin; suture api)ressed, distinct and wavy; keel prominent on 

 body-whorl; base flat, with faint spiral sculpture; aperture subovate; columellar protuberance on 

 some specimens. 



Dimensions.— Ah. 40 mm.; lat. 45 mm.; dell. 70 degrees. 



Tbis species is characterized by the prominent nodose keel on anterior marijin 

 of wborl. Although the living specimens are common, the fossils are rare in this 

 locabty. 



Upper San Pedro series of San Pedro and Crawlisii George's. Found also in 

 the Pleistocene at Pacific Beach, San Diego. 



Living. — Santa Barbara to ("ape St. Lucas; Monterey ? (Cooper). 



Pleistocene. — Santa P>arbara to San Diego (Cooper): San Pedro; San Diego 

 (Arnold). 



Genus Leptothyra Carpenter. 



Shell small, turbinated, thick; not unibilicated; aperture circular, slightly angulated 

 anteriorly. 



Type, Lcplothyrn carpenleri Carpenter. 



