70 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Subgenus Gregariella Monterosata, 1883. 
Modiolus opifex Say, 1825. 
•Jour. Acad. Nat. Set. Philo*, 4:369; pi. 19, fig. 2. 
Oval, reddish brown; anterior hinge-margin flattened, cordate; within 
iridescent. Base contracted behind the middle, the contraction not wide 
nor very deep; between this part and the beaks the surface is blackish and 
transversely wrinkled; posterior and anterior surface of the valve longi¬ 
tudinally striated, with the exception of the anterior cordate hinge-margin, 
which is flattened and covered by a thick stratum of compact sand; 
anterior tip equally arcuated above and below; within iridiscent, brilliant, 
striated as on the exterior surface, edge crenate. Breadth nearly half an 
inch; length more than one-fifth of an inch. (Say.) 
Type in Phila. Acad. Nat. Sci. Type locality not known to the writer. 
Range. Santa Barbara, California, to the Gulf of California. 
Subgenus Braciiydontes Swainson, 1840. 
Modiolus demissus Dillwyn, 1817. 
Plate 27, fig. 1. 
Descr. Cat. Pec. Shells, 1:314. Jour. Acad. Nat. Sci. Phila., 7; pi. 20, fig. 7. 
Shell about three inches long, and an inch-and-a-quarter broad; of a 
silvery white color, covered with a dark brown epidermis; the valves are 
covered with strong longitudinal stria*, except a small space on the anterior 
side below the hinge which is nearly smooth; the margin crenated and the 
inside white, indistinctly rayed with purple. (Dillwyn.) 
This is the manuscript description of Solender, published by Dillwyn. 
This species has been known under the name of M. plicatula Lamarck, 
1819. 
Type. The writer does not know where the type is. Type locality, 
Coasts of Carolina. 
Range. San Francisco Bay. Imported with “seed” oysters from the 
Atlantic. 
Genus BOTULA Morch, 1853. 
Surface deeply, concentrically sulcate, shell inflated, with conspicuously 
spiral umbos, the epidermis polished. (Dali.) 
Type. Mytilns cinnamomeus Lamarck. 
Distribution. West Indies, New Zealand, California, Pacific Coast. 
Range in time. In the Carboniferous of Europe and the United 
States. 
