30 Merriarn — Tvo Nev^ Highm-nK (i)ul a New Aiifehqje. 



Ovis mexicanus sp. nov. 



Type from Lake Santa Maria, Chihuahua. No. 1)9,342 (^ ad. U. S. 

 National Museum, Biological Survey Collection. Collected Sept. 16, 

 1899 by E. W. Nelson and E. A. Goldman. Orig. No. 13,974. 



Characters. — Size large; color dark, much darker than ndmni but less 

 dark than ranadensis; horns large; massive, dark, not strongly out- 

 curved; hoofs and molars larger than in 0. canadensis; ears long and 

 large, nearly double the size of those of canadensis, measuring from 

 occiput, in dry skin, 110-110 mm.; tail long and slender, measuring 

 about 130 mm. Color pattern similar to that of caiiademis. 



Color. — Body color above and below drab brown, darkest on throat, 

 legs, and tail; no trace of dorsal stripe; muzzle decidedly paler than rest 

 of face; rump patch broader and more squarely truncate anteriorly than 

 in canadensis; dark color on hind leg covering much more of inner side 

 of thigh than in canadensis; but much less of lower leg, the white 

 spreading broadly over the posterior and inner aspects, and on the inner 

 side ending abruptly just above the calcaneal joint; whitish of chin 

 broader and less sliarply defined. 



Cranial characters. — Skull as a whole large and massive. Compared 

 with canadensis, orbits less prominent; frontals flatter (less 'dished' in 

 forehead); basioccipital narrow, its sides nearly parallel, its muscular 

 facets small and median sulcus broad; occiput (viewed from behind) 

 much narrower; depth of face (above molars) less; permaxillfe longer, 

 more slender, and reaching much farther back; jugal relatively small 

 and less expanded anteriorly; lachrymal long, reaching well out toward 

 premaxilla; paroccipital narrower and more slender; lips of posterior 

 nares (behind hamulars) thin and somewhat everted [in canadensis 

 thickened and much sicollen]; angle of mandible obsolete; coronoid 

 process lower and less expanded. Molar teeth larger. Horn cores 

 longer, with longer curve and less flaring base. 



Horns. — Large and heavy, but longer and less massive than those of 

 canade?isis; upper (flat) side narrower; base less flaring; orbital corner 

 shortly rounded oft" (not produced). 



Measurements. — Type specimen, (^ ad.: Total length 1530; tail verte- 

 brae 130; hind foot 425; height at shoulder 900. An ad. 9 fi'om type 

 locality: total length 1490; tail vertebrne 130; hind foot 405; height at 

 shoulder 880. 



In examining a number of skulls of the Bighorn in the col- 

 lection of the U. S. National Museum it is found that tliose 

 from the Plains region of the western Dakotas and eastern 

 Montana differ in important characters from those from the 

 Rocky Mountains in Montana and Alberta. These differences 

 appear to be constant and necessitate the recognition of the 

 Plains animal as a subspecies of Onis canadensis. The chief 

 differences are the great size of the molar teeth and the massive- 



