148 BULLETIN 112, UNITED STATES NATIONAL MUSEUM. 



BITTIUM FETELLUM Bartsch, 1911. 



Proc. U. S. Nat. Mus., vol. 40, p. 409, pi. 51, fig. 4. 

 Off Catalina Island in 16 fathoms. 



BITTIUM GIGANTEUM Bartsch, 1911. 



Proc. U. S. Nat. Mus., vol. 40, p. 410, pi. 55, fig. 2. 

 Pleistocene of San Pedro and San Diego, California. 



Genus POTAMIDES Brongniart, 1810. 



Subgenus Pireneela Gray, 1847. 



PIRENELLA CYCLUS Dall, 1919. 



Proc. U. S. Nat. Mus., vol. 56, p. 346. 



Long Beach, California, to Gulf of California. 



Subgenus Lioceritiiium Tryon, 1887. 



LIOCERITHIUM SCULPTUM Sowerby, 1855. 



Thes. Conch., vol. 2, p. 868, figs. 144, 145. 



Santa Barbara Islands, California, to Panama and the Galapagos Islands. 



Genus CERITHIDEA Swainson, 1840. 



CERITHIDEA CALIFORNICA Haldeman, 1840. 



Mon. Freshwater Shells, N. Amer., cover of No. 1. — Tryon, Man., vol. 9, 



pi. 33, figs. 69, 70, 71. 

 Baulinas Bay to San Diego, California. 



Family TRICHOTROPIDAE. 

 Genus TRICHOTROPIS Sowerby, 1829. 



TRICHOTROPIS BICARINATA Sowerby, 1825. 



Tankerville Catalogue, pp. 55, XII, pi. 9. 



Arctic Ocean from Point Barrow south, on the west to the Okhotsk Sea and 

 Shantar Islands, and on the east to Nunivak Island, Bering Sea. 



TRICHOTROPIS CONICA Moller, 1842. 



Index Moll. Gronl., p. 82.— Tryon, Man., vol. 9, pi. 7, fig. 45. 

 Forrester Island, Alaska ; also Greenland. 



TRICHOTROPIS COSTELLATA Couthouy, 1838. 



Boston Journ. Nat. Hist., vol. 2, p. 108, pi. 3, fig. 2. 



Arctic Seas, Bering Sea, the Aleutian Islands and south to the Queen 

 Charlotte Islands, British Columbia; also New England coast. 



TRICHOTROPIS CANCELLATA Hinds, 1843. 



Proc. Zool. Soc, p. 17 ; Zool. Voy. Sulphur, Moll., pi. 11, figs. 11, 12. 

 Southern part of Bering Sea, and south to Oregon. 



TRICHOTROPIS INSIGNTS Middendorff, 1849. 



Beitr. Mai. Rossica, p. 107, pi. 10, fig. 7-9. 



From Bering Strait south, on the west to Northern Japan, and on the east 

 to the Aleutian Islands and Cooks Inlet, Alaska. 



