widely flaring; mastoid bullae and tympanic bullae more inflated; incisors smaller; maxillary teeth relatively larger. For comparison of _consitus_ with _Cratogeomys castanops sordidulus_, see previous account. _Remarks._--_Cratogeomys castanops consitus_ is a small pocket gopher (see tables 1 and 2); the largest adult available to us is much smaller than the smallest adult of any adjacent subspecies. Specimens from Coahuila assigned to _consitus_ compare favorably with topotypes although those from the vicinity of Jaco are smaller, paler and have a narrower rostrum and smaller maxillary teeth. An immature male trapped three miles northeast of Sierra Mojada is tentatively assigned to _consitus_. This subspecies seems to be rare in northwestern Coahuila and small colonies are widely scattered. _Cratogeomys castanops clarkii_ (Baird) may occur along the Río Grande in extreme northwestern Coahuila. No specimens are known from Coahuila, and none was found in the vicinity of Boquillas, Coahuila, in 1952. _Specimens examined._--Total, 8, from: 3 mi. N and 9 mi. E El Pino, 1; 6 mi. E Jaco, Chihuahua, _in_ Coahuila, 6; 3 mi. NE Sierra Mojada, 1. +Cratogeomys castanops excelsus+ Nelson and Goldman 1934. _Cratogeomys castanops excelsus_ Nelson and Goldman, Proc. Biol. Soc. Washington, 47:143, June 13, type from San Pedro, 10 mi. W Laguna de Mayrán, Coahuila. _Distribution._--Desert plains of southwestern Coahuila and northeastern Durango (see fig. 1). _Comparisons._--_Cratogeomys castanops excelsus_ is characterized by large size and pale color; it is the palest subspecies of _C. castanops_. Of adjacent subspecies, excelsus most closely resembles _C. c. subsimus_ which occurs to the east and resembles least _C. c. consitus_, which occurs to the northwest. From _Cratogeomys castanops subsimus_, found to the east, _excelsus_ differs in: Body averaging slightly larger; tail and hind foot shorter; upper parts paler, more light buffy and less yellowish; skull smaller; palate especially shorter; rostrum narrower; nasals shorter; incisors slightly smaller; maxillary tooth-row shorter. Compared with topotypes of _C. c. goldmani_, found to the south, _excelsus_ differs in: Body larger; hind foot smaller; upper parts in winter pelage paler, more buffy and less rufous; skull larger; zygomata more widely flaring; rostrum broader; nasals shorter; tympanic bullae larger and more inflated; maxillary teeth larger. Specimens of _excelsus_ from the vicinity of Torreón, in southwestern Coahuila, are slightly smaller in cranial dimensions than more typical examples of the subspecies. In small size, at least, these specimens show some resemblance to _goldmani_ to the south. The range of _excelsus_ approaches that of _C. c. consitus_ in west-central Coahuila (see fig. 1), but no evidence of intergradation between these two subspecies could be ascertained. For comparison of _excelsus_ with _consitus_, see account of the latter.