Part 13

Specimens examined, 5: nos. 50325-50329 (U. S. Nat. Mus.) from QuerA(C)ndaro.

Remarks.--The specimens from QuerA(C)ndaro are not typical of the subspecies L. i. alleni in that the shape of the interparietal bone and width of the basisphenoid bone are almost exactly intermediate between the conditions obtaining in typical L. i. alleni and topotypes of L. i. acutus.

=Reithrodontomys megalotis saturatus= Allen and Chapman

Western Harvest Mouse; Spanish, RatA cubedn Orejudo

Reithrodontomys saturatus Allen and Chapman, Bull. Amer. Mus. Nat. Hist., 9:201, June 16, 1897, type from Las Vigas, Veracruz.

Reithrodontomys megalotis saturatus, Howell, N. Amer. Fauna, 36:36, June 5, 1914.

Range.--Northeastern part of state.

Specimens examined, 12: nos. 100202-100212, 100273, from 1 mi. N Zamora, 5,450 ft.

Remarks.--Howell (1914:37) referred nine specimens from Nahuatzin to this race and two from the same place to the subspecies R. m. zacatecae. Our specimens from Zamora agree with topotypes of R. m. saturatus and with specimens of that subspecies from the Valley of MA(C)xico 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, RatA cubedn Orejudo

Reithrodontomys megalotis zacatecae Merriam, Proc. Washington 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 PAitzcuaro, 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 PatambAin to this subspecies, and our large series from the vicinity of PAitzcuaro 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 PAitzcuaro area showing much wear on the teeth compared with those of five specimens from the Zamora area, of corresponding sex 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, RatA cubedn 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 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.