_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.