32 HOOFED ANIMALS 
genus Opts in its progress southward. At Pinacate and the 
Seri Mountains it is stopped by aridity, heat, thirst and the 
general scarcity of food. In 1907 we collected several speci- 
mens on the awful lava-fields of Pinacate, and we found that 
there the robust Big-Horn of the North had greatly diminished 
in size. The rams measured only 37 inches in shoulder height, 
which is from 3 to 4 inches below the normal height farther 
north. The legs were short, and delicately formed, the hoofs 
were small, the pelage was very short and thin and the weight 
of rams was about 30 per cent under the average figures for 
northern adult animals. 
Southward of the range of the Big-Horn are found three 
new species which appear to be offshoots of it. In southern 
California is found the CaLirorNIA or NELSON’s MouNnTAIN 
SHEEP,’ a smaller animal than the big-horn, short-haired, and 
of a pale salmon-gray color. On the peninsula of Lower Cal- 
ifornia there is to be found—if looked for during the next five 
years—a short-haired, large-horned species that has been 
described as Ovis cremnobates. Of this species some fine heads 
exist in New York and Philadelphia collections of big-game 
heads. 
In the state of Chihuahua, Mexico, is found the Mex- 
1cAN MovuntTAIN SHEEP,” in color much like the Californian 
species, but larger, and with large ears. The horns some- 
times measure 164 inches in basal circumference. This 
species 1s now almost, if not quite, extinct. 
THe Waitt Mountain SHEEP, or DALw’s SHEEP,® of 
Alaska, discovered and described by E. W. Nelson in 1884, 
1 QO’vis nel’son-t. 2 O'vis mex-i-can'us. 3 O'vts dall’t. 
