66 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
impressions two in each valve, small, simple, close to the adductor. (Tryon. 
S. S. Conch.) 
Type. Mytilus edulis Linnseus. 
Distribution. World-wide. Ochotsk, Bering Sea, Russian Ice-meer; 
Black Sea, Cape Horn, New Zealand. 
Range in time. Silurian of United States, Europe, South India. 
Mytilus californianus Conrad, 1837. 
Plate 27, fig. 2. 
Jour. Acad. Nat. Sci. Phila., 7 :242; pi. 18, fig. 15. 
Shell ovate elongated, inflated; anterior margin straight; posterior side 
emarginate; ribs not very numerous, slightly prominent, broad, rounded; 
lines of growth very prominent. Length, 2 % inches. (Conrad.) 
Type in U. S. N. M. or Phila. Acad. Nat. Sci. or State Museum at 
Albany, New York. Type locality, San Diego, California. 
Range. Unalaska, Aleutian Islands, to Socorro Islands. In the Pleis¬ 
tocene, California, and Pliocene, San Fernando, California. 
Mytilus edulis Linnaeus, 1758. 
Plate 27, fig. 4. 
Syst. Nat. ed. 10, p. 705. Gould, Invert. Mass.; fig. 82. 
M. testa laeviuscula violacea, valvulis obliquis postice acuminatis. 
(Linnaeus.) 
Shell obliquely triangular, concentrically striated, blue-black, olive, 
rayed with black, rather compressed posteriorly, anteriorly arcuately im¬ 
pressed. (Conch. Iconica.) 
Type in British Museum? Type locality, North Atlantic. 
Range. Arctic Ocean to San Diego and world-wide in temperate 
waters. In the Pliocene, Benicia, Solano County, and San Diego, Cali¬ 
fornia. 
SECTION HORMOMYA Morch, 1856. 
Mytilus adamsianus Dunker, 1856. 
Plate 29, fig. 4. 
Proc. Zool. Soc., 1856, p. 360; Conch. Iconica, Mytilus, pi. 11, fig. 55. 
M. testa ovato-trigona, utrinque obtuse carinata, solidula, costis mature 
bifidis eleganter granosis sculpta, fusco-purpurascente et albida; epider- 
mide cornea vestita; umbonibus terminalibus; margine crenato. 10 lin. 
longa, Syi lin. alta, 4j4 lin. lata. (Dunker.) 
Shell ovately triangular, very gibbous, posteriorly flatly compressed, 
attenuately beaked at the umbones, fan-shaped anteriorly, everywhere 
neatly flexuously ribbed, ribs granularly serrated, dichotomous toward the 
margin; olive, tinged with black. (Conch. Iconica.) 
