Two subspecies of _Cratogeomys castanops_ occur in Tamaulipas, _C. c.
planifrons_ in the higher elevations of the Sierra Madre Oriental in
the western part of the state, and _C. c. tamaulipensis_ on the plains
of the Rio Grande.
Specimens from Miquihuana were trapped in tunnels at 6400 feet
elevation. At Palmillas, individuals were trapped in an area of
mesquite, other bushes and "lechuguilla." Three specimens from
southeast of Reynosa were collected in traps set along the dikes of
irrigation ditches. Most specimens from Nicolas were brought by natives
to the collector, but some were caught in traps set in tunnels among
the desert bushes.
=Cratogeomys castanops planifrons= Nelson and Goldman
1943. _Cratogeomys castanops planifrons_ Nelson and Goldman,
Proc. Biol. Soc. Washington, 47:146, June 13, type from
Miquihuana, 5000 ft., Tamaulipas.
_Distribution in Tamaulipas._--Higher elevations in
southwestern part of state.
Specimens from four miles north of Jaumave do not differ from specimens
from Miquihuana. The weights of nine females averaged 146.4 (110-210)
grams; three males weighed 178, 203, and 215 grams.
_Records of occurrence._--Specimens examined, 29:
Miquihuana, 6400 ft., 9; 4 mi. N Jaumave, 2500 ft., 5;
Nicolas, 56 km. NW Tula, 5500 ft., 15.
=Cratogeomys castanops tamaulipensis= Nelson and Goldman
1934. _Cratogeomys castanops tamaulipensis_ Nelson and
Goldman, Proc. Biol. Soc. Washington, 47:141, June 13, type
from Matamoros, Tamaulipas.
_Distribution in Tamaulipas._--Known only from two
localities in extreme northern part of state, but probably
occurs throughout northeastern part of state.
Three specimens from three miles southeast of Reynosa are referred to
_C. c. tamaulipensis_ on geographic grounds. They are tawny brown
dorsally instead of cinnamon brown or pinkish cinnamon as Nelson and
Goldman (1943:141) described _tamaulipensis_, and the basioccipital
bone (in one male) is parallel-sided instead of wedge-shaped. Possibly
this difference is owing to sex; Nelson and Goldman studied only one
adult, a female (the type), and the only adult seen by me was a male.
_Measurements._--An adult male (58118) from three miles
southeast of Reynosa, measured as follows: 301; 81; 40; 7;
condylobasal length, 57.0; zygomatic breadth, 41.2; palatal
length, 36.1; breadth of rostrum, 11.8; length of nasals,
22.0; squamosal breadth, 34.0; alveolar length of maxillary
tooth-row, 10.8.
_Records of occurrence._--Specimens examined, 3, from 3 mi.
SE Reynosa.
Additional record: Matamoros (Nelson and Goldman, 1934:140).
=Perognathus merriami merriami= J. A. Allen