MAMMALS OF THE MEXICAN BOUNDARY. 333 



the base, with the lateral angle less marked. Qnderjaw larger and heavier, with 

 posterior edge of inflected angular process broader, shorter, and less t ransverse. The 

 cranium as a whole is narrower and higher than in any known member of the sub- 

 genus Xerospermophilus. 



The dentition is unusually heavy for the subgenus, and the crown of the last upper 

 molar is aboui as long antero-posteriorly as transversely. The first upper premolar 

 is about one-third the size of the second. In all of these respects, except the char- 

 acter of the angular process of the mandible, the cranial peculiarities of S. anneciens 

 depart from the S. spilosoma type and resemble the S. mexicana type. 



innri-nl remarks. — Fourteen specimens of this animal are in the [U. S."| Departs 

 merit [of Agriculture] collection, thirteen from Padre Island, Texas, and one from 

 the mainland at the mouth of the Rio Grande. Padre Island is a long spit of sand 

 in the Gulf of Mexico, just north of the mouth of the Rio Grande. (Proc. Biol. Soc. 

 Washington, VIII, pp. 132, 133.) 



CITELLUS SPILOSOMA MACROSPILOTUS (Merriam). 

 APACHE GROUND SQUIRREL. 



Spermophilus spilosoma macrospilotus Merriam, North American Fauna, No. 4, 

 Oct. 8, 1890, p. 38 (original description; normal orreddish phase, from Oracle, 

 Pinal County, Arizona). — Miller and Rehn, Proc. Bost. Soc. Nat. Hist., 

 XXX, No. 1, Dec. 27, 1901, p. 55 (Syst. Results study X. Am. Mam. to close 

 of 1900) . 



Spermophilus canescens Merriam, North American Fauna, No. 1. <>ct. 8, L890, 

 p. 38 (grayish phase, from Willcox, Cochise County. Arizona I. 



Spermophilus {Xerospermophilus) microspilotus, Elliot, Field Col. Mus., Zool. Ser., 

 II, 1901, lig. 21 (Synop. .Mam. X. Am.). 



[Spermophilus spilosoma] microspilotus, Elliot, Field Col. Mus., Zool. Ser., II, 

 mill, p. 96 (Synop. Mam. X. Am.). 



Citellus {Xerospermophilus) s. microspilotus, Elliot, Field Col. Mus., Zool. Ser., 

 IV, 1904, pp. 144, 145, fig. 25 (Mam. Mid. Am. t. 



Typer locality. — Oracle, Pinal County, Arizona. (Type, skin and 

 skull, No. i'JdiU' i't the U.S. National Museum, Biological Survey 

 Collection). 



Geographical range. — Sonoran Zone, in the Elevated Central Tract. 



Description. Much darker and more strongly colored than the 

 typical form of the Eastern Desert Tract. Length, ~1'1^ nun.; tail ver- 

 tebrae, 75 (to end of hairs, 95); hind foot, 30. Skull, 35 by 22. Mammae, 

 five pairs. Ground color russet- brown, mixed with a few light-tipped 

 hairs. Spots large, roundish, and far apart. Tail eoneolor with the 

 body on its proximal half; yellow, ringed with black, on terminal half: 

 and yellow beneath. Feet and under surfaces white. Skull (fig. .~>4) 

 apparently smaller and relatively broader than in the typical form. 



The gray phase. " Spermophilus canescens ," is described by Doctor 

 Merriam as follows: 



( 'olor.— Upper parts drab-gray, much obscured by hoary; head and face hoary; hack 

 every where covered with transversely elongated whitish mat kings, which are much 

 crowded and tend to run together laterally, forming transverse wavy Oars, separated 

 by narrower dark wavy lines, consisting of the dark tips of the hairs. Eyelids and 



