NO. 2057. THE GRASSHOPPER MICE—HOLLISTER. 451 



Oeneral characters. — General coloration exceedingly pale, without 

 distinct markings, and with white of imderparts extending onto 

 shoulders and upper sides. 



Color. — Adult in full winter coat (50040, Samalayuca, Chihuahua, 

 December 12; type): General color of upperparts pale vinaceous-bufif, 

 darkest on crown, lower back, and rump, where the color becomes 

 almost hght pinldsh-cinnamon ; nose to crown whitish; ear tufts pure 

 wliite; eai-s scantly furred with whitish; underfur of back slate-gray. 

 Lips, cheeks, region back of ears, sides, legs, and feet white, the hairs 

 everywhere except on upper sides pure white to bases. Tail pale- 

 grayish above, whitish below; not sharply bicolor. Two shghtly 

 younger specimens from the type-locaUty differ somewhat from the 

 type, but both are very pale. One (50042, December 18) lacks the 

 buffy general color and is decidedly grayish above. 



Slcull and teeth. — The skull of albescens resembles those of longipes 

 and hreviauritus in general shape more than other forms of the group. 

 Compared with ruidosse, it is long and slender with higher, less flattened 

 braincase. The teeth are small. 



Measurements of type. — Total length, 160 millimeters; tail verte- 

 bras, 60; liind foot, 23; ear from notch in dry skin, 15.6. Skull: 

 Condylobasal length, 26.0; zygomatic breadth, 14.2; interorbital 

 breadth, 14.8; breadth of braincase, 12.9; length of nasals, 11.6; 

 length of mandible, 15.0; maxiUary tooth row, 4.3. 



Type-specimen. — No. 50040, United States National Museum, 

 Biological Survey Collection. Skin and skuU of young adult male 

 (teeth moderately worn and basal suture open), in fresh full winter 

 coat. Collected December 12, 1892, by C. P. Streator. Original 

 number 2399. 



RemarTcs. — This is a local form, restricted, so far as known, to the 

 sand dunes in the vicinity of Samalayuca, Chihuahua, and northward 

 to the Rio Grande, opposite El Paso, Texas. Specimens from the 

 Lower Sonoran deserts of Otero County, New Mexico, are pale and 

 are distinctly approaching this race in color, but are best placed with 

 the wider ranging ruidosx. 



Specimens examined. — Total number 6, from: 



Chihuahua: Mexican boundary line, opposite El Paso, 3; Sama- 

 layuca, 3 (type and paratypes). 



ONYCHOMYS LETTCOGASTER LONGIPES Merrlam. 



1888. Cricetus (Onychomys) leucogaster Thomas, Proc. Zool. Soc. London, 1888, 

 p. 445. 



1889. Onychomys longipes Merriam, North Amer. Fauna, No. 2, p. 1. October 20. 

 1901. [Onychomys leucogaster] longipes Elliot, Field Col. Mus., pub. 45, zool.eer., 



vol. 2, p. 120. 

 1913. Onychomys leucogaster longipes Hollister, Proc. Biol. Soc. Washington, vol. 

 26, p. 216. December 20. 



Type-locality. — Concho County^ Texas. 



Geographic distribution. — Central and southern Texas and Nuevo 

 Leon and TamauUpas, Mexico. North to Tom Green and Concho 



