MAMMALS OK TilK MKXK'AN l',<H : N I ).\ KY . 



871 



ONYCHOMYS PALLESCENS (Merriam). 



EASTERN DESERT GRASSHOPPER MOUSE. 



Onychomys melanophrys pal/fscnin Mkkkiam, North America Fauna, No. 3, Sept. 11, 



1890, pp. 61, 62 (original description). Miller and Rehn, Proc. Bost.Soc. Nat. 

 Hist., XXX, No. I. Dec 27, L901,p.67 (Syst. Results Study X. Am. .Mam. to close 



of 1900). 

 [Onychomys leucogaster] palleseens Elliot, Field Col. Mus., Zool. Ser., II, 1901, p. 121 



(Synop. Mam. N. Am.). 

 0[nychomys] m[elanophrys] palleseens, Elliot, Field Col. Mus., Zool. Ser., IN'. 1904, 



pp. 165 and ltiti (Mam. Mid. Am.). 



Eaton of the Mexicans. 



Type-locality. — Hopi pueblos, Apache County, Arizona. (Type, 

 skin and skull, No. ffff, collection of Dr. C. Hart Merriam.) 



Geographical range. — Sonora i i zone 

 of the desert basins of the upper Rio 

 Grande and Little Colorado rivers — 

 the Eastern Desert Tract. 



Description. — Smaller than 0. long- 

 ipes or 0. melanophrys. Average 

 measurements of six adults: Length, 

 IV.) mm.; tail vertebrae, 51 (to end of 

 pencil, 54); ear above crown, 15; ear 

 above notch, 18.5; length of hind 

 foot, 23. Skull (fig. 61a), 30 by 16. 

 Coloration, very pale; above, pale 

 annulated hairs, becoming paler and 

 grayish on the head and brighter 

 tawny cinnamon, but slightly mixed 

 with black-tipped and black cinnamon on the Hanks and rump; palest 

 specimens, light fawn color or ecru drab above; under surface, feet, 

 and end of tail white; ears bufl'y white, with a large seal-brown spot 

 on anterior border of convex surface and conspicuous lannginous 

 tufts at anterior base; dusky stripe on upper side of tail, obsolete. 

 Mamma": P|, A. §, I. |=3 pairs. 



This desert mouse was found by us only from El Paso, Texas, to the 

 Mimbres Valley, near Monument No. 15 of the boundary. From that 

 point westward to the San Bernardino Valley, at Monument No. 77, 

 we found no large species of Onychomys. The San Bernardino form, 

 which we refer to 0. melanophrys, is the darkest of the group, excepting 

 Onychomys fuliginosus Merriam, from the pifion and cedar bolt and 

 the black lava beds between San Francisco Mountain and the deserl 

 of the Little Colorado, which has a dark, almost blackish, coloration, 

 unique in the genus. 



Fig.CI.— Onychomys pallesi ens. a Skull; 

 b, Lower molars, i i pper molars. 



