118 CALIFORNIA ACADEMY OF SCIENCES. 



and San Pedro. Found also in the Pleistocene at Barlow's ranch, Ventura, and in 

 the Pleistocene of Spanish Bight and Pacific Beach, San Diego. 



Living. — Monterey to Mexico (Cooper). 



Pleistocene. — San Pedro (Cooper; Arnold): Ventura; San Diego (Arnold). 



[S. D.] Anomia limatula Dull. 



Anoviia limahda Dall, Pioc. U. S. Nat. Mus., Vol. I, 1879, p. 15. Trans. Wagner Inst. Sci., Vol. 

 Ill, Part 4, 1898, p. 785, PI. XXXV, fig. 19. 



Shell large, thin, irregular, with a rather thickened hinge-line; external surface rough, like 

 fresh fractured china-ware; surface devoid of all normal radial sculpture, and still retaining on its 

 yellowish valves traces of dark purple, irregularly radial blotches. The calcareous plug of this 

 species is peculiar, being hollow, and the cylinder incomplete on one side. 



Distinguishable from A. lampe and Pododesmvs macroschisma by its lack of 

 radial sculpture. Reported in the Pleistocene of San Pedro by Stearns. 



Pleidocene. — San Pedro (Stearns): Ventura County, eight miles inland and 

 two hundred feet elevation above sea-level (Bowers): Spanish Bight and Coronado 

 Beach, San Diego (Hemphill; Stearns): Twenty-sixth Street, San Diego (Hemphill; 

 Arnold). 



Superfamily MYTILACEA. 

 Family XII. MYTILIDTK. 



Genus Mytilus (Linne) Bolten. 



Shell wedge-shaped, rounded behind; umbones terminal, pointed ; hinge-teeth minute or 

 obsolete; jiedal muscular impressions two in each valve, small, simple, clo.se to the adductors. 



Mytilus smaragdiwis Chemn. is a characteristic species. 



Section Mytilus .s. .<;. 

 Surface with chiefly concentric sculpture, or smooth. 

 Type, Mijtilus edulis Linnc'. 



40. Mytilus edulis Linne. 



Mytilus edulis Linn., Syst. Nat., Ed. X, 1758, p. 705. -^ M. borealis Lam. = M. abbreviatus Lam. 

 = M. velustus Lam. = M. incurvatus Lam. = M. pellucidus Pennant = M. notatus 

 DeKay = M. subsaxatilis Williamson (fide Carpenter, Brit. Assn. Rept., 1856, p. 

 219). Carpenter, Brit. Assn. Rept., 1863, p. 643. Cooper, 7th Ann. Rept. Cal. St. 

 Min., 1888, p. 252. Keep, West Coast Shells, p. 173, 1S92. Williamson, Proc, 

 U. S. Nat. Mus., Vol.XV, 1892, p. 191. =. Modiola pulcx H. C. Lea (not of Lam.) 

 = Mytilus viinganensis Mighels, &c. {fide Dall, Wagner Inst. Sci., Vol. Ill, Part 4, 

 1898, p. 788). 



Mytilus pedroavns Con., Pac. R. R. Rept., Vol. V, 1853, p. 325, PI. V, fig. 40. 



