450 BULLETIN" 56, UNITED STATES NATIONAL MUSEUM. 



Description. — This race is much smaller, paler, and grayer than 

 Sigmodon hispidus texianus or S. h. arizonse, and lacks their brown 

 color, which is replaced by gray. Above soiled grayish, finely mixed 

 with black. Below pure white. Tail quite hairy, with the median 

 upper surface dusky. Ear much larger, actually as well as relatively, 

 than that of S. h. texianus. Length, 242 mm.; tail vertebrae, 103; 

 ear from crown, 14; hind foot, 30. Skull 

 (about) 30 by 18 mm. (See also p. 453). The 

 teeth are shown in fig. 111. 



Comparisons. — This, the smallest of the four 

 geograpliical races of Sigmodon hispidus found on 

 the Mexican line, dift'ers from the almost equally 

 pallid form of the Western Desert {Sigmodon hispi- 

 dus eremicus) in being of a grayish instead of a 



Fig. 111.— Sigmodon his- n • i i • i i •' • i 



piDus BERLANDiERi. ycilowish color, and m lackmg the termmal 

 CROWN OF MOLAR TEETH, gxpansiou of tlic uasals. The cotton-rat of the 



a, UPPER series; 6, , 



LOWER SERIES. Elcvatcd Central Iract (o. /;. arizonx) is so much 



larger and darker than either of the desert forms 



(Jberlandieri and eremicus) that further comparison is unnecessary. 



SIGMODON HISPIDUS ARIZONiE Mearns. 

 ARIZONA COTTON-RAT. 



Sigmodon hispidus arizonx. Mearns, Bull. Am. Mus. Nat. Hist., II, p. 287, Feb. 21, 1890 

 (original description). — Allen, Bull. Am. Mus. Nat. Hist., Ill, 1891, p. 208 (in 

 text); V, 1893, p. 28 (" One specimen from Granados [on the Yacjui River], Nov. 

 16"); VII, 1895, p. 220 (critical remarks on a dozen specimens taken at Fairbank, 

 on the San Pedro River, Arizona). — Miller and Reiin, Proc. Bost. Soc. Nat. Hist., 

 XXX, No. 1, Dec. 27, 1901, p. 90 (Syst. Results Study N. Am. Mam. to close of 

 1900) ; XXXI, Aug. 27, 1903, p. 80 (Syst. Results Study N. Am. Mam. during the 

 years 1901 and 1902).— Bailey, Proc. Biol. Soc. Washington, XV, p. 108, June 2, 

 1902 (Synopsis of the North American .Species of Sigmodon). 



[Sigmodon hispidus] arizonsR, Elliot, Field Col. Mus., Zool. Ser., II, 1901, p. 144 

 (Synop. Mam. N. Am.). 



[Sigmodon] hispidus arizonse, Elliot, Field Col. Mus., Zool. Ser., IV, 1904, p. 228 (Mam. 

 Mid. Am.). 

 Kahl'-ld of the Hopi Indians. 

 Tu'-sa or Ah-me-la of the Hualapai Indians. 



Type-locality . — Alfalfa fields on the Verde River at Fort Verde, 

 Yavapai County, Arizona. (Type, skin and skull. Cat. No. ^14^, 

 American Museum of Natural History.) 



Geographical range. — -Inhabits the Elevated Central Tract from Fort 

 Verde, Arizona, to Granados, in Sonora, Mexico. 



Description. — Size large. Coloration darker than that of the desert 

 forms {pallidus and eremicus) on either side of its range, but paler 

 than in the coast forms (hispidus, littoralis, texianus, etc.). Above 

 light yellowish bro^vn, mixed with ashy, lined rather sparingly with 

 black; below white; pelage everywhere plumbeous at base; tail 

 dusky above, whitish below. Ears large, orbicular, clothed with 



