1896. _Spermophilus mexicanus parvidens_ Mearns, Preliminary
diagnoses of new mammals from the Mexican border of the
United States, p. 1, March 25, type from Fort Clark, Kinney
Co., Texas.
_Distribution in Tamaulipas._--Northern part of state, south
at least to Xicotencatl.
Most of the specimens examined from Tamaulipas are in the brown phase
(Howell, 1938:121) and differ from _S. m. parvidens_ from Texas,
Coahuila, and Nuevo Leon in being darker dorsally. Nevertheless, some
individuals are as pale as those examined from the mentioned states.
Measurements of Tamaulipan specimens average smaller than those given
by Howell (1938:121) and Baker (1956:205) for _parvidens_.
Specimens from San Fernando differ slightly from those from Soto la
Marina in having a relatively long tail (average 69.2 instead of 62.1
per cent of length of head and body) and in having the upper parts of
the hind feet ochraceous instead of nearly white.
Two May-taken females from Soto la Marina carried 5 and 7 embryos that
were 10 mm. in crown-rump length; another taken there was lactating.
Weight of six non-pregnant females from San Fernando averaged 160.6
(129-197) grams. Two males from the same locality weighed 164 and 145
grams.
_Measurements._--Average and extreme measurements of four
males and three females from Soto la Marina are, as follows:
312.6 (296-330); 119.8 (110-130); 41.6 (38-43). Average
cranial measurements of five specimens (two males, three
females) from same locality are: greatest length of skull,
44.7 (43.7-47.4); zygomatic breadth, 26.9 (25.3-28.6);
breadth of braincase, 19.4 (19.2-19.5); interorbital
constriction, 13.3 (12.5-14.1); length of nasals, 15.9
(14.6-17.5); length of maxillary tooth-row, 8.3 (8.0-8.5).
_Records of occurrence._--Specimens examined, 20: San
Fernando, 180 ft., 12; Soto la Marina, 500 ft., 8.
Additional records (Howell, 1938:121 unless otherwise
noted): Nuevo Laredo; Mier; Camargo; Reynosa; Bagdad;
Victoria; Xecotencatl [= Xicotencatl] (J. A. Allen,
1891:223).
=Spermophilus spilosoma oricolus= Alvarez