_Type._--Obtained at Old Fort Yuma, Imperial County, California, by G. H. Thomas; catalogued in U. S. National Museum on October 31, 1861. _Measurements._--A specimen from Maryhill, Klickitat County, measures: total length 68; length of tail 27; hind foot 7; ear 10; height of tragus 3; weight 4.2 grams. Two males from Vantage, Grant County, average: 68.5; 27.5; 6; 11; 4. _Distribution._--Known only from along the Snake and Columbia rivers of south-central Washington; recorded from Vantage (W.W.D.), south to Maryhill (M.V.Z.), and east to Almota (Taylor and Shaw, 1929: 9). _Description._--This is the smallest bat found in Washington, its body being approximately 1-3/4 inches long and the tail 1-1/4. It may be separated from _Myotis_ by the bent tragus and by the possession of 34 rather than 38 teeth. The dental formula is: i. 2-2/3-3, c. 1-1/1-1, p. 2-2/2-2, m. 3-3/3-3 = 34. The genus _Pipestrellus_ is cosmopolitan in distribution. The few records for the single subspecies found in Washington indicate that it is a casual, though probably regular, summer visitant from the south. Two western pipistrelles were shot at Vantage, Grant County, on July 23, 1937. They flew in slow circles about 50 feet from the ground. No breeding records are known from the state. =Eptesicus fuscus bernardinus= Rhoads Big brown-bat _Eptesicus fuscus bernardinus_ Rhoads, Proc. Acad. Nat. Sci. Philadelphia, 1901:619, February 6, 1902. _Eptesicus fuscus pallidus_ Engels, Amer. Midland Nat., 17:656, May, 1936 (part specimens from Washington). _Type._--Obtained near San Bernardino, San Bernardino County, California, by R. B. Herron on May 26, 1893; type in Academy of Natural Sciences of Philadelphia. _Measurements._--Three males and 5 females from Washington average: total length 117; length of tail 48; hind foot 11.5; ear 18.3; height of tragus 9. _Distribution._--Forested areas of the entire state of Washington. Marginal localities are San Juan Island (W.W.D.) in the northwest, Carson (Taylor and Shaw, 1929: 9), in the southwest, Newport (W.W.D.) in the northeast, and Grand Ronde River (Taylor and Shaw, 1929: 9) in the southeast. _Remarks._--Specimens from both eastern and western Washington vary greatly in color, and series of specimens from eastern Washington average little, if any, paler than series from western Washington. Washington specimens most closely resemble specimens from California of the race _bernardinus_ and average darker than _pallidus_. _Description._ The big brown-bat may be distinguished from other bats by its large size (about 4-1/2 inches), rich, brown color, and small ears (reaching only to nostril when laid forward). It possesses 32 teeth, the dental formula being: i. 2-2/3-3, c. 1-1/1-1, p. 1-1/2-2, m. 3-3/3-3 = 32.