126 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Subgenus Here Gabb, 1866 
Phacoides richthofeni Gabb, 1866. 
Pal. Cal., 2:29; pi. 8, fig. 49. 
Shell subglobose, nearly equilateral; beaks small, inclined forward; 
margins regularly rounded; a more or less distinctly marked groove 
passes from the beaks to the posterior margin. Surface marked by 
numerous, more or less regular, distinct rounded ribs. (Gabb.) 
Type in University of California Collection. Type locality, Fernando 
Valley north of Los Angeles in the Pliocene. 
Range. San Pedro, California, to Cape St. Lucas, Lower California, 
recent. In the Pliocene at San Fernando, California. 
Subgenus Lucinisca Dali, 1901. 
Phacoides nuttallii Conrad, 1837. 
Jour. Acad. Nat. SciPhila., p. 255; pi. 20, fig. 2. 
Shell lenticular, slightly compressed; disks cancellated; concentric 
lines very regular, lamelliform, prominent; anterior fold small, marginal; 
extremity emarginate above; cardinal and lateral teeth distinct; inner 
margin minutely crenulated. (Conrad.) 
Type in Acad. Nat. Sci., Phila.? Type locality, California. 
Range. Santa Barbara, California, to Mazatlan, Mexico. In the 
Pliocene at San Diego and the Pleistocene at Santa Barbara, San Pedro, 
and San Diego, California. 
Subgenus Lucinoma Dali, 1901. 
Phacoides annulatus Reeve, 1850. 
Plate 33, figs. 5a, 5b. 
Conch. Iconica, Lucina, 6; pi. 4, fig. 17. 
Shell orbicular, rather flattened, inequilateral, concentrically laminately 
ridged, ridges sharp, erect, interstices concentrically striated, lunule lanceo- 
lately ovate, rather deeply excavated; semi-transparent white. (Reeve.) 
Type in Cuming Collection. Type locality, California. 
Range. Port Althorp, Alaska, to the Coronado Islands, Lower Cali¬ 
fornia. In the Upper Miocene at Santa Margarita and the Pliocene and 
Pleistocene in California. 
Phacoides annulatus densiliratus Dali, 1919. 
Proc. Biol. Soc. Wash., 32:249. 
The typical P. annulatus has the concentric sculpture rather regularly 
and widely spaced; this variety has it closely crowded and less lamellose, 
giving a different aspect to the shell, which otherwise does not differ from 
