18 RECENT BIVALVE MOLLUSKS 



Genus Septifer Recluz, 1848. 



Septifer bifurcatus (Conrad) Reeve, 1837. 



Crescent City, Cal., to Gulf of California. 

 Septifer bifurcatus var. obsoletits Dall, 1916. 



San Diego, Cal. 



Gciiiis Modiolus Lamarck, 1799. 



Modiolus modiolus Linne, 1758. 



Circumboreal. On the Pacific side Arctic and Bering Seas 



and southward to San Pedro, Cal., and the outlying 



islands. 

 Modiolus rectus Conrad, 1837. 



Bolinas Bay, Cal., to Magdalena Bay, Lower California. 

 Modiolus flabellatus Gould, 1850. 



Vancouver Island to San Diego, Cal. 

 Modiolus capax Conrad, 1837. 



Santa Barbara, Cal., to Payta, Peru. 

 Modiolus fornicatus Carpenter, 1864. 



Monterey to San Pedro and Cortez Bank, California. 

 Modiolus politus Verrill, 1880, var. palUdulus Dall. 1916. 



OfT Bodega Head. Cal., and south to Cerros Island, Lower 



California, in deep water. 



Suhgcniis Gregariella Monterosato, 1883. 



Gregariella opifex Say. 1825. 



Santa Barbara, Cal., to Gulf of California. 



Subgenus Brachydontes Swainson, 1840. 



Brachydontes demissus Dillwyn, 1817. 



Imported with "seed" oysters from the Atlantic Coast. 

 San Francisco Bay, on oyster beds. 



Genus Botula Morch, 1853. 

 Subgenus Adula H. and A. Adams, 1857. 



Adula diegensis Dall, 1911. 



San Francisco Bay, to Cape St. Lucas. Free. 



Adula falcata Gould, 1851. 



Coos Bay, Oregon, to San Diego, Cal. Burrowing. 



Adula calif orniensis Philippi, 1847. 



Vancouver Island to San Diego, Cal. North Japan. Bur- 

 rowing. 



Gouts Dacrydium Torell, 1859. 



Dacrydium pacificum Dall, 1916. 

 Bering Sea, 1401 fathoms. 



