=Lagurus curtatus pauperrimus= (Cooper) Sagebrush vole _Arvicola pauperrima_ Cooper, Amer. Nat., 2:535, December, 1868. _Arvicola pauperrimus_ Merriam, N. Amer. Fauna, 5:64, July 30, 1891. _L[agurus]. pauperrimus_ Thomas, Ann. and Mag. Nat. Hist., ser. 8, 9:401, April, 1912. _Microtus pauperrimus_ Bailey, N. Amer. Fauna, 55:214, August 29, 1936. _Lemmiscus pauperrimus_ Davis, Recent Mamm. Idaho, Caxton Printers, p. 327, April 5, 1939. _Lemmiscus curtatus pauperrimus_ Goldman, Proc. Biol. Soc. Washington, 54:70, July 31, 1941. _Type._--Obtained on the "Plains of the Columbia" near the Snake River, southwestern Washington by J. G. Cooper on October 9, 1860. Probably from the Bunchgrass Hills near Wallula (Old Fort Walla Walla), Walla Walla County: type in United States National Museum. _Measurements._--Bailey (1900: 69) gives the average of 3 adults from the vicinity of Antelope, Oregon, as: total length 115; length of tail 20; hind foot 16. _Distribution._--Known in Washington only from the type and a specimen from Badger Mountains, 8 miles southwest of Waterville (Taylor and Shaw, 1929: 25). _Remarks._--This rare vole is the smallest microtine rodent in Washington. The head and body measure about 4 inches and the tail about 1 inch. The upper parts are grayish or yellowish brown and the underparts grayish. The upper incisors are not grooved and the inner and outer angles of the molars are about equal in length. Mice of the genus _Lagurus_ occur in Siberia and in prairie areas of the northwestern United States and Canada. The sagebrush vole inhabits the Upper Sonoran Life-zone. It prefers upland areas of low sagebrush with sparse grass. Poorly formed runways and small piles of feces indicate its presence. The type of _Lagurus pauperrimus_ was obtained in southwestern Washington 80 years ago, and a single additional record has since been obtained. Nothing is known of its habits in Washington. The life history of related forms has been reported on by Hall (1928: 201-204) from Nevada and Moore (1943: 188-191) from Oregon. Davis (1939: 326) raised the subgenus _Lemmiscus_ Thomas (for American forms) to generic rank and Goldman (1941: 69) accepted this usage. Comparison of the Siberian and American species reveals but three impressive differences: the dorsal stripe of the Siberian mice, the greater development of prisms in the molars of the American species, and the presence of cement in the angles of the molars of the Siberian specimens and its lack in the American. These differences seem to be of no more than subgeneric value. Goldman (1941: 69) showed that all American _Lagurus_ belong to a single species. =Ondatra zibethicus= (Linnaeus) Muskrat