Produced by Chris Curnow, Tom Cos, Joseph Cooper and the Online Distributed Proofreading Team at http://www.pgdp.net ~University of Kansas Publications~ ~Museum of Natural History~ Volume 7, No. 12, pp. 591-608 March 15, 1955 Geographic Variation in the Pocket Gopher, Cratogeomys castanops, in Coahuila, México BY ROBERT J. RUSSELL AND ROLLIN H. BAKER ~University of Kansas~ ~Lawrence~ 1955 ~University of Kansas Publications, Museum of Natural History~ Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Robert W. Wilson Volume 7, No. 12, pp. 591-608 Published March 15, 1955 ~University of Kansas~ ~Lawrence, Kansas~ PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA, KANSAS 1955 25-5679 Geographic Variation in the Pocket Gopher, Cratogeomys castanops, in Coahuila, México By Robert J. Russell and Rollin H. Baker The plateau pocket gopher, _Cratogeomys castanops_, inhabits open lands from southeastern Colorado southward onto the Mexican Plateau as far south as southern San Luis Potosí and southeastern Zacatecas and southeastward to the Coastal Plain of northern Tamaulipas. This species occurs at elevations from as low as 26 feet at Matamoras in Tamaulipas to as high as 8700 feet in valleys of south-eastern Coahuila. In 1934, Nelson and Goldman (Proc. Biol. Soc. Washington, 47:135-154, June 13, 1934) revised the genus _Cratogeomys_ and decided that six subspecies of _C. castanops_ occurred in Coahuila. In the present account, we describe four previously unknown subspecies from Coahuila, exclude from the state two others recorded from there by Nelson and Goldman, and show that three others named previously from adjacent Mexican states do occur in Coahuila. This makes eleven subspecies now known from that state. From Coahuila Nelson and Goldman had 35 study specimens of _C. castanops_ from seven localities and we have had 234 specimens from 63 localities. Consequently we have been able to define with greater certainty, than formerly was possible, the geographic distribution of _C. castanops_ in this Mexican state and similarly analyze more completely the geographic variation.