AKNOLD — THK FALF.ONTOLOCY AND STKATIGKAl'HY Of SAN I'EDUO. 327 



I'lvUtocene. — Saiilu Jj;irliaia to Sail Diego (Cooper): San I'eilro; .Sail Diego 

 (Ariiolcl). 



I'liocene. — Sun Peiiro (Arnold). 



Subgenus Omphalius Philippi. 



Shell coiivex-trocliiform, umbilicated; whorls with revolving series of granules; the last 

 whorl hluntly anijulated at the periphery; umbilicus encircled by a callosity; columellar lip termi- 

 nated by a tooth anteriorly, below which are small tubercles; outer lip usually internally grooved. 



Chloroduma viriditlus Gmel. is a characteristic species. 



377. Chlorostoma (Omphalius) viridulum var. ligulatum Menke. 



Trochus ligulalus Menke, Zeit. f. Mai., 1850, p. 173. Fischer, Coq. Viv., p. 3S2, PI. CXV, fig. 5. 



Oniphaliiis lignlatus Menke, Cpr., Cat. Mazatlan Shells, p 235. 



Oiiif>/ia/ius fiiscescens Phil., Cpr., Proc. Zool. Soc, 1S56, p. 224. Ci'k., Brit. Assn. Rept., 1S63, 



p. 652. Cooper, 7th Ann. Rept. Cal. St. .Min., 1888, p. 255. Keep, West Coast 



Shells, p. 82, fig. 68, 1892. 

 Tiochiis luridus Nutt., Cpr., niss., Brit. Assn. Rept., 1856, p. 233. 

 Chlorostoma {Omphalitis) viridulum var. ligulatum Menke, Tryon, Man. Conch., Vol. XI, p. 177, 



PI. XXIX, figs. 58-60, 1889. Dall, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 200. 



Shell turbinated, thick; whorls five, conve.\ to nearly flat; body-whorl subangular at base; 

 01 naineiitation consists of seven to eight prominent nodose spiral ridges; suture distinct, sometimes 

 ([uite deeply impressed; base flat, with ornamentation same as whorls, except less prominent; 

 umbilicus deep, effuse, smooth; outer lip efl'use, denticulated on lower portion. 



Dimensions. — Alt. 17 mm.; lat. 18 nun.; defl. 80 degrees. 



Some of the specimens show the mottled coloration of the live shell. 

 Distinguishable b}' denticulation and ornamentation. 



Rare in lower San Pedro scries of Deadman Island ami San Pedro; common 

 in the upper San Pedro series of Los Cerritos and Crawlish George's; but rare in the 

 upper San Pedro series of Deadman Island and San Pedro. 



Licing. — Cataliiia Island to San Diego (Cooper): Mazatlan (Carpenter). 



Pleistocene. — San Pedro (Cooper; vVriiold). 



Genus Thalotia Gray. 



-Shell ovate-turriculaled, rather thick; not umbilicated; whorls flattened, with revolving ribs, 

 which are sometimes granulated; aperture subrotund; columella tuberculated, truncate in front; outer 

 lip rather thick, crenulated within. 



Thnlotin conicus Gray is a characteristic species. 



378. Thalotia caffea Gabh. 



Turrica 1 Ptyc/istjlis) caffea Gabb, Proc. Cal. Acad. Sci., Vol. Ill, 1865, p. 187; Pal. Cal., Vol. II, 



pp. 16, 84, PI. Ill, fig. 27. 1869. 

 Thalotia caff,a Gabb, Cooper, Geog. Cat. West Coast Shells, p. 26, 1S67. Cooper, 7th Ann. 



Rept. Cal. St. Min., 188S, p. 267. 



