MAMMALS OP THE MEXICAN BOUNDARY. 209 



Type-locality. — Sierra Seri, Sonora, Mexico, and region around 

 the head of the Gulf of California. 



Geographical range. — Deserts and desert ranges of the Western 

 Desert Tract ; both sides of the Colorado River and around the head 

 of the Gulf of California, occupying the Lower Sonoran Life Zone. 

 It occurs on Tiburon Island. 



Description. — A large deer. Mr. H. von Bayer shot a buck, sup- 

 posedly of this form, on Tiburon Island, in the Gulf of California, 

 which weighed 120 pounds avoirdupois when dressed. A number of 

 these deer were shot for food by members of the surveying parties; 

 but, unfortunately, I was not present to measure and preserve them 

 as specimens, though I sometimes saw some of the deer alive when 

 hunting in the Nariz and Quitobaquita mountains. On this account 

 the materials for description were fragmentary and unsatisfactory. 

 I was indebted to Dr. W J McGee, then of the Bureau of Ethnol- 

 ogy, for a single skin of this deer. This specimen (No. 63403, 

 U.S.N.M.), an adult male in full winter pelage, was taken by Doctor 

 McGee on an expedition to. Seriland, in the Sierra Seri, near the Gulf 

 of California, in December, 1895. The locality is in the most arid 

 portion of Sonora, Mexico. Like all mammals of this Western Des- 

 ert Tract it is remarkable for the extreme pallor of its coloration. 

 The coat is short and glossy. Upper parts very pale drab gray, with 

 a dark vertebral area, which begins as a narrow median stripe on the 

 upper side of the neck, broadens and becomes fainter on the back, 

 forms a blackish spot at the root of the tail, down which it descends 

 for a short distance. The buttocks, inguinal and abdominal regions, 

 and the middle of the tail all round are white. The axillae and hol- 

 lows of the thighs are entirely naked. The edges of the buttocks, 

 posterior surface of limbs, and the feet are washed with pale, n;iuddy 

 cinnamon.' The chest is light sooty drab. Tail with a heavy brush 

 or short switch of black hair at the tip, the middle portion being 

 white all round, the dusky color extending a short distance down- 

 ward, on the upper side, froni the blackish spot at its base. While 

 the general effect is to produce a pale drab-gray coloring of the upper 

 surface, there is the usual pepper and salt commingling of colors, 

 produced by light and dark annulation of the hairs, those of the 

 vertebral area being pointed with brownish black. 



There is no complete skull for description. The horns are very 

 characteristic. They are heavy and very divergent, being chiefly 

 remarkable for the great length of the beam before forking. In a 

 youngish specimen from the Cerro Salado in the Sonoyta Valley 

 (No. 59910, U.S.N.M.), the distance from the burr to the" first fork, 

 following the curve of the beam, is 320 mm. The total expanse of 

 this pair of horns is 620 mm. They are doubly dichotomous through- 

 out, having four points, besides a basal snag on each horn. Referring 

 30039— No. 56—07 m 14 



