_Reithrodontomys tenuis_ Allen, Bull. Amer. Mus. Nat. Hist.,
12:15, March 4, 1899, type from Rosario, Sinaloa.
_Reithrodontomys fulvescens tenuis_, Howell, N. Amer. Fauna,
36:45, June 5, 1914.
_Range._--Western part of state.
_Specimens examined_, 27: nos. 100213-100216, 100274-100277,
100293-100311, distributed by localities as follows: 11 mi. W Zamora,
5,750 ft., 2; 6-1/2 mi. W Zamora, 5,950 ft., 2; 6 mi. W Zamora, 5,950
ft., 4; 1-1/2 mi. SSE TacAimbaro, 5,700 ft., 2; 1-3/4 mi. S TacAimbaro,
5,700 ft., 1; 1 mi. E and 2-1/2 mi. S TacAimbaro, 7; 4 mi. S and 1 mi.
E TacAimbaro, 4,700 ft., 5; 1 mi. E and 5 mi. S TacAimbaro, 4,000 ft.,
1; 1 mi. E and 6 mi. S TacAimbaro, 4,000 ft., 3.
_Remarks._--Of the 19 specimens from the vicinity of TacAimbaro, only
two have the underparts reddish as does _R. f. inexspectatus_. The
upper parts are less reddish than in _R. f. inexspectatus_ but more
reddish and less blackish than in _R. f. toltecus_ from the valley of
MA(C)xico or than in _R. f. toltecus_ from Zamora. The external
measurements and cranial measurements are less than in _R. f.
toltecus_ or _R. f. inexspectatus_ and are as small as, or even
smaller than, those of _R. f. tenuis_ to the northward or than those
of _R. f. nelsoni_ to the westward. Relying only on printed
descriptions of _R. f. tenuis_ and _R. f. nelsoni_, we are inclined to
refer our specimens to _R. f. tenuis_ although the reddish color, we
suppose, is evidence of intergradation with _R. f. nelsoni_ and _R. f.
inexspectatus_.
The four skins from Zamora are gray, as opposed to reddish, both above
and below and in this respect they agree with the description of _R.
f. tenuis_. They are lighter-colored (grayer) than either _R. f.
toltecus_ or _R. f. inexspectatus_. The four specimens from Zamora are
larger than animals from the vicinity of TacAimbaro and average
slightly smaller than topotypes of _R. f. inexspectatus_.
By identifying our specimens as _R. f. inexspectatus_ and _R. f.
tenuis_, we are left without any specimens that we, ourselves, have
examined, which are referable to the subspecies _R. f. toltecus_. The
specimens from Los Reyes which Howell (1914:47) referred to _R. f.
toltecus_ have not been seen by us, and we guess, on the criteria used
by us, that the animals would be referable to _R. f. tenuis_. Because
Dr. Emmet T. Hooper has a revisionary study of the Mexican
_Reithrodontomys_ underway, we have not attempted to bring together
all of the pertinent material from different collections as would be
required for an ideally thorough analysis of the geographic variation
in _Reithrodontomys megalotis_ and _Reithrodontomys fulvescens_.
As illustrative of statements made concerning the average size of
_Reithrodontomys fulvescens_, the following measurements, all of
specimens with much wear on each of the molar teeth, are recorded.
Table headings:
A: Number averaged or catalogue No.
B: Sex
C: Total length
D: Length of tail
E: Length of hind foot
F: Basilar length
G: Length of nasals
H: Zygomatic breadth
I: Mastoid breadth
J: Alveolar length of maxillary tooth-row
=========================================================================
LOCALITY A B C D E F G H I J
-------------------------------------------------------------------------
Vall. Mex. 3 [M][M] 200 114 22.0 17.6 9.3 12.0 10.7 3.7
PAitzcuaro 5 [M][M] 170 101 20.6 16.7 8.7 11.6 10.6 3.7
Zamora 100215 [M] 153 82 19.0 15.9 7.8 10.9 10.3 3.5
Zamora 100275 [M] 184 101 21.0 16.5 8.0 11.1 10.4 3.6
TacAimbaro 5 [M][M] 159 91 19.4 15.5 8.0 10.5 9.6 3.3
Vall. Mex. 3 [F][F] 184 103 21.0 16.6 8.7 11.4 10.6 3.6
PAitzcuaro 5 [F][F] 182 104 21.6 16.8 8.6 11.6 10.5 3.6
Zamora 5 [F][F] 159 91 19.0 16.0 8.4 11.4 10.0 3.5
TacAimbaro 5 [F][F] 149 87 18.6 14.9 7.7 10.4 9.5 3.4
-------------------------------------------------------------------------
Note: [M] = Male and [F] = Female.
=Reithrodontomys fulvescens inexspectatus= Elliot