mentioned above, intergradation with _Microtus montanus nanus_ is seen in the specimens from Hood River and Wapinitia. In the specimens from Hood River the auditory bullae are only slightly less inflated than in those topotypes of _canicaudus_ having the smallest bullae; there is appreciable variation in size of the bullae in the topotypes. Even so, the minimum size of bullae among the topotypes is larger than the maximum size in the specimens from Wapinitia. The four specimens from Wapinitia have the yellowish color of _canicaudus_ to a considerable degree, and show intergradation between _canicaudus_ and _nanus_ in depth of the palatal pits and shape of interpterygoid space. The slightly larger size of these specimens from Wapinitia suggests intergradation with _M. m. montanus_. The tympanic bullae in the specimens from Wapinitia seem to be smaller than in specimens of _canicaudus_, _nanus_, or _montanus_. Because of the intergradation described above between _Microtus montanus nanus_ and _M. canicaudus_, the latter should stand as _Microtus montanus canicaudus_. * * * * * Bailey (N. Amer. Fauna, 55:206, August 29, 1936) recorded _canicaudus_ from Warm Springs in the Deschutes Valley of Oregon and from the state of Washington. Other authors also have recorded _canicaudus_ from the state of Washington. Our examination of specimens leads us to conclude, as did Dalquest (Univ. Kansas Publ., Mus. Nat. Hist., 2:348, 349, April 9, 1948), that _canicaudus_ does not occur in Washington. The reported occurrence of _M. canicaudus_ at Warm Springs, Deschutes Valley, Oregon, seems to be the result of an error in identification. The specimens concerned seem to be two _Microtus longicaudus mordax_ (Nos. 207060 and 207082 U.S.N.M.). They are labeled as collected at "Warm Springs (Mill Cr.--20 Mi. W of)". Bailey's (_op. cit._, fig. 46, p. 209) map showing the distribution in Oregon of _Microtus mordax mordax_ [=_Microtus longicaudus mordax_] has a locality-dot at Warm Springs itself. Bailey seems to have erred; he should have placed this dot 20 miles farther west, we think. When preparing his map (_op. cit._, fig. 43, p. 205) showing the geographic distribution of _Microtus canicaudus_, Bailey seems to have misidentified these same two specimens as _M. canicaudus_, and for them placed a locality-dot on his map 20 miles east (instead of west) of Warm Springs. In brief, Bailey probably did not see any specimens of _canicaudus_ or specimens of any other subspecies of _Microtus montanus_ from Warm Springs. _Transmitted February 15, 1951._ 23-7438