AKNOLD — THE PALEONTOLOGY AND STIJATIOKAPTIY OF SAN PEDKO. 327 



Pkistncene. — Santa Barbara to 8aii Dic'i;o (Cooper): San Pedro; San Diego 

 (Arnold). 



Pliocene. — San Podri) (Arnold). 



Subgenus Omphalius rhilippi. 



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

 whorl bluntly angulated 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. 



Chlorostoma viridulus Gmel. is a cbaracterLstic species. 



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



Trochus liguiatus Menke, Zcit. f. Mai., 1850, p. 173. Fischer, Coq. Viv., p. 382, PI. CXV, fig. 5. 



Omphalhis ligiilatus Menke, Cpr., Cat. Mazatlan Shells, p 235. 



Omphalius fuscescens Phil., Cpr., Proc. Zool. Soc, 1856, p. 224. Cpr., Brit. Assn. Rept., 1863, 



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



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

 Trochus luridus Nl'tt., Cpr., mss., Brit. Assn. Rept., 1856, p. 233. 

 Chlorostoma {Omphalius) viridiilutn var. ligulatum Menke, Trvon, 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.x to nearly flat; body-whorl subangular at base; 

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

 quite deeply impressed; base flat, with ornamentation same as whorls, e.xcept less prominent; 

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



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



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

 Distinguishable by denticulution and ornamentation. 



Rare in lower San Pedro series of Deadraan Island and San Pedro; common 

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

 upper San Pedro series of Deadman Island and San Pedro. 



Living. — Catalina Island to San Diego (Cooper): Mazatlan (Carpenter). 



Pleiiftocene. — San Pedro (Cooper; Arnold). 



Genus Thalotia Gray. 



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

 which are sometimes granulated; a|)erture subrotund; columella tuberculated, truncate in fi-ont; outtr 

 lip rather thick, crenulated within. 



Jlialotia conicus Gray is a characteristic species. 



378. Thalotia caffea (iahh. 



Turcica ( Plyckstylis) caffea Gabb, Proc. Cal. Acad. Sci., Vol. Ill, 1865, p. 187; Pal. Cal., Vol. II, 



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

 Thalotia caffea Gabb, Cooper, Geog. Cat. West Coast Shells, p. 26, 1867. Cooper, 7th Ann. 



Rept. Cal. St. Min., 1888, p. 267. 



