ila 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 Torreon, 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.

_Remarks._--_Cratogeomys castanops excelsus_ lives in the deep soils
of the arid interior basin of southwestern Coahuila and adjacent
parts of Durango. This animal is common in the cultivated areas in,
and in the vicinity of, the formerly extensive Laguna de Mayran. East
of this laguna the land becomes progressively higher, and _C. c.
subsimus_ occurs in the higher, more dissected part of this area.

_Specimens examined._--Total, 33, from: 8 mi. E and 2 mi. S
Americanos, 3500 ft., 3; 4 mi. N Acatita, 3600 ft., 9; 20 mi. S El
Hundido, 1; San Pedro, 2 (BSC); _1 mi. SW San Pedro de las Colonias,
3700 ft._, 4; 10 mi. N and 11 mi. W San Lorenzo, 2; 2 mi. E Torreon,
12.

+Cratogeomys castanops subsimus+ Nelson and Goldman

1934. _Cratogeomys castanops subsimus_ Nelson and Goldman, Proc. Biol.
Soc. Washington, 47:144, June 13, type from Jaral, Coahuila.

_Distribution._--Desert plains and lower foothi