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zacatecae_. Our specimens from Zamora agree with topotypes of _R. m.

saturatus_ and with specimens of that subspecies from the Valley of Mexico in dark color and large size.

If our specimens of _Reithrodontomys megalotis_ are correctly identified, subspecifically, _R. m. zacatecae_ ranges southward around the western end of the geographic range of _R. m. saturatus_.

Where _R. megalotis_ and _R. fulvescens_ occur together, we find the skull of the latter to be distinguishable by: a median spine on the posterior border of the hard palate (truncate in _R. megalotis_); an S-shaped instead of a C-shaped pattern on the worn occlusal face of the last lower molar; and two re-entrant angles, on the lateral side on the worn occlusal surface of the third upper molar, reaching halfway across the tooth whereas in _R. megalotis_ the anterior re-entrant angle is wanting or extends less than a third of the way across the crown surface of the tooth.

=Reithrodontomys megalotis zacatecae= Merriam

Western Harvest Mouse; Spanish, Raton Orejudo

_Reithrodontomys megalotis zacatecae_ Merriam, Proc.

Was.h.i.+ngton Acad. Sci., 3:557, November 29, 1901, type from Valparaiso Mountains, Zacatecas.

_Range._--From northwestern part of state south through its central part.

_Specimens examined_, 53: nos. 100217-100269; distributed by localities, with reference to Patzcuaro, as follows: 3 mi. N, 6,700 ft., 3; 3 mi. N, 6,800 ft., 1; 3-1/2 mi. S, 7,900 ft., 3; 4 mi.

S, 7,800 ft., 31; 5 mi. S, 7,800 ft., 9; 9 mi. SE, 8,000 ft., 6.

_Remarks._--Howell (1914:40) has referred four specimens from Patamban to this subspecies, and our large series from the vicinity of Patzcuaro is also referred to _R. m. zacatecae_ because of small size and reddish (less blackish) color. We lack typical specimens of _R. m.

zacatecae_ from the type locality for comparison and our knowledge of _zacatecae_ is derived from Howell's (1914:39) description of it.

Average measurements of 5 adult males of _R. m. zacatecae_ from the Patzcuaro area showing much wear on the teeth compared with those of five specimens from the Zamora area, of corresponding s.e.x and age of _R. m. saturatus_ reveal the smaller size of _R. m. zacatecae_. Total length, 157, 166; length of tail, 84, 84; length of hind foot, 19.6, 20.1; length of ear from notch in flesh, 14.8, 14.0; basilar length, 16.2, 16.6; length of nasals, 8.3, 8.5; zygomatic breadth, 11.1, 11.5; mastoid breadth, 9.9, 10.2; breadth of rostrum, 3.8, 4.0; interorbital construction, 3.2, 3.1; alveolar length of maxillary tooth-row, 3.5, 3.5; length of rostrum, 7.7, 8.0.

=Reithrodontomys fulvescens tenuis= Allen

Fulvous Harvest Mouse; Spanish, Raton Moreno

_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 Tacambaro, 5,700 ft., 2; 1-3/4 mi. S Tacambaro, 5,700 ft., 1; 1 mi. E and 2-1/2 mi. S Tacambaro, 7; 4 mi. S and 1 mi.

E Tacambaro, 4,700 ft., 5; 1 mi. E and 5 mi. S Tacambaro, 4,000 ft., 1; 1 mi. E and 6 mi. S Tacambaro, 4,000 ft., 3.

_Remarks._--Of the 19 specimens from the vicinity of Tacambaro, 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 Mexico 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.

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