ARNOLD — THE PALEONTOLOGY AND STIIATIUKAI'UY OF SAN PEDUO. 301 



Shell tiirreted, with slender, taperinjj spire; number of whorls variable; whorls flat, with two 

 distinct spiral ridges on anterior portion and three or four less distinct ridges posteriorly; incremental 

 lines distinct and concave anteriorly; suture thread-like and rather indistinct, not usually impressed; 

 aperture angular. 



Dimensions. — Defi. i6 degrees. 



The spiral sculpture in this species is quite variable, the prominence of the 

 various ridges not being constant; the suture is also somewhat imi)ressed in some 

 specimens. A more solid shell than T. cnoperi, being less slender, having more 

 prominent spiral sculpture, a more aiigulnr ;i|)erturc and a less distinct suture than 

 the latter species. The shell listed by Mrs. Williamson as 2\ sanguinea from the San 

 Pedro Pleistocene is probably this species, as Carpenter in his original description 

 (the type being a Pleistocene fossil from Santa Parbara) says that T. jeweitii is near 

 7\ s(mgumea. 



Common in the Pliocene, rarer in llic lower San Pedro series, and still rarer in 

 the upper San Pedro series of San Pedro and vicinity. The specimen figured is from 

 the Pliocene of Deadman Island, and is now in the collection of Delos Arnold. 



Pleistocene. — Santa Barbara to San Diego (Cooper): San Pedro (Arnold). 



Pliocene. — San Diego well (Dall): San Pedro (ArnoUl). 



Family LXXIII. LITTORIXID.E. 



Genus Littorina Ferussac. 



Shell turbinated, thick, pointed, few-whorled; aperture rounded; outer lip acute; columella 

 rather flattened, imperforate. 



Littorina Utorea Tjiiin. is a characteristic species. 



332. Littorina planaxis {Nuttall) Philippi. 



Littorina planaxis Nutt., Philippi, teste Cpr., Proc. Zool. Soc, 1856, p. 266. Cpr., Brit. Assn. 

 Rept., 1863, p. 655. Gabb, Pal. Cal., Vol. II, p. 80, 1869. Tryon, Man. Conch., 

 Vol. IX, p. 248, PI. XLIII, figs. 55, 56; PI. XLIV, fig. 57, 1887. Cooper, 7th Ann. 

 Rept. Cal. St. Min., 1888, p. 246. Keep, West Coast Shells, p. 68, fig. 53, 1892. 

 ^=L. patula Gld. {fide Dall, Trans. Wagner Inst. Sci., Vol. Ill, Part 2, 1892, p. 321). 

 Williamson, Proc. U. S. NaL Mus., Vol. XV, 1892, p. 205. 



Shell small, broadly conical; spire not much elevated; whorls three, convex, the last being 

 ventricose; surface roughened by lines of growth; aperture ovate; outer lip thin; inner lip and 

 columella flattened and eftuse. 



Dimensio7is. — Alt. 8 mm.; lat. 6.2 mm.; aperture 5 mm. x 3.5 mm.; defl. 70 degrees. 



Distinguishable from L. scutulata by lack of coloration, rough surface, very 

 effuse inner lip, greater deflection, and fewer whorls. Specimens identified by 

 Dr. Dall. 



One specimen each, from the upper San Pedro series of Sau Pedro, and 



