MAMMALS OF THE MEXICAN BOUNDARY. 333 



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

 posterior edge of inflected angular process broader, shorter, and less transverse. 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 about 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. annectens 

 jJepart from the S. spilosoma type and resemble the »S'. mexicana type. 



General remarks. — Fourteen specimens of this animal are in the [U. S.] Depart- 

 ment [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 Eio Grande. (Proc. Biol. Soc. 

 Washington, VIII, pp. 132,133.) 



CITELLUS SPILOSOMA MACROSPILOTUS (Merriam). 

 AFACEE GROUND-SQTriKKEL. 



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

 Oct. 8, 1890, p. 38 (original description; normal or reddish 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 N. Am. Mam. to close 

 of 1900). 



Spermophilus canescens Merriam, North American Fauna, No. 4, Oct. 8, 1890, 

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



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

 II, 1901, flg. 21 (Synop. Mam. N. Am.). 



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

 1901, p. 96 (Synop. Mam. N. Am.). 



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

 IV, 1904, pp. 144, 145, flg. 25 (Mam. Mid. Am.). 



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

 , skull, No. jf Ms in the U. S. National Museum, Biological Survey 

 Collection). 



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



Descriptixm. — Much darker and more stronglj' colored than the 

 typical form of the Eastern Desert Tract. Length, 220 mm.-; tailver- 

 tebrse, 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 concolor with the 

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

 and yellow beneath. Feet and under surfaces white. Ski(ll (fig. 54) 

 apparently smaller and relatively broader than in the typical form. 



The gray phase, '"'' Spermophilus canescens^'' is described \)y Doctor 

 Merriam as follows: 



Color. — Upper parts drab-gray, much obscured by hoary; head and face hoary; back 

 everywhere covered with transversely elongated whitish markings, which are much 

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

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



