NO. 2057. THE GRASSHOPPER MICE—HOLLISTER. 457 



vinaceous or pale pinkish-gray and buff; the overlying hair tips worn 

 or faded and the brownish-black wash on back and rump less con- 

 spicuous as a consequence; lanuginous ear tufts less contrasted from 

 smTomiding color and therefore much less conspicuous. Adult in 

 new pelage, late summer and fall (21215, San Pedro River, Ai-izona, 

 October 25): Darkest annual stage of adult. Pelage short, glossy, 

 and with little red. Upperparts of head and body uniform wood 

 brown, finely lined with darker; cheeks, shoulders, and sides very 

 slightly paler, with less blackish-brown suffusion from darker hair 

 tips; underfur broadly dark neutral-gray, the grayish-brown tips 

 comparatively short; ear tufts wanting or inconspicuous, not notice- 

 ably contrasting in color fi'om head. Underparts gi'ayish-white, the 

 slaty underfur showing through the thinly haired chest, belly, and 

 limbs. Tail comparatively thinly haired, dark brown above, tip 

 and underside whitish. Juvenile pelage (66085, Dos Cabezos, Aii- 

 zona, June 22): Above uniform mouse-gi'ay, the hair tips only 

 slightly hghter than the underfur; ear tufts gi-ayish; ears blackish 

 outside, rimmed with white; dark brown inside, thinly haired with 

 whitish. Underparts grayish- white; tail not sharply bicolor as in 

 adult, the upper side gi-ay, the under side and tip grayish- white. 

 This juvenile pelage moults and renews directly into the post-juvenile 

 pelage, which is worn until the following summer or autumn. Post- 

 juvenile pelage (132056, Colonia Diaz, Chihuahua, January 19): 

 Above browner, less slaty-gray, than in the juvenile coat. General 

 color of upperparts grayish-hair-bro\vn, with a decided tendency 

 toward drab, finely hned with darker. Underparts clear whitish. 

 Tail sharply bicolor, the brown Ime along upper surface very narrow. 

 Slcull. — The skull, in general shape, is not conspicuously different 

 from that of other forms of the torridus group. It is of medium 

 size with comparatively narrow zygomatic breadth. The anterior 

 palatine foramina are large, widely spreading forward of center, and 

 extend backward to or beyond plane of anterior edge of m^ usually 

 fully to plane of second cusp of that tooth. The palate appears, 

 therefore, very short, and this appearance is accentuated by the 

 deeply concave posterior edge, normally without indication of spine. 

 In occasional immature specimens from throughout the range of 

 the form, and in many adults from the extreme western limits of its 

 distribution in Arizona and Sonora, the posterior edge of the palate 

 develops a well-formed spine, as in the neighboring races on the 

 west and south. Skulls from these western locahties show a stiU 

 further approach toward perpallidus in the shortening of the anterior 

 palatine foramina, though the sidns from this region retain the high 

 coloration of true torridus. (Plate 15.) 



Measurements.— A.YQVQige^ and extremes of twenty-three speci- 

 mens from Arizona, New Mexico, Sonora, and Chihuahua: Total 



