130 Proceedings of the Biological Society of Washington. 



range, and practically no cactus on or near it. The nearest water is 20 

 miles away in the Gilas. There are no signs of anybody having been 

 there for a long time. Lumholtz rode a horse partly around it and re- 

 ported sheep tracks.* This report induced me to go there, for I felt that 

 if there were sheep on the mountain they would show the effects of long 

 isolation and inbreeding. They must live without water other than that 

 obtained from the scarce rains and scanty vegetation. 



I rode over there from Wellton in three days, packed water from the 

 Gila Range, and remained alone for eight days, climbing the crags and 

 hunting for sheep. I soon found that sheep existed there, but only a 

 very few, perhaps not more than five or six, certainly less than ten. At 

 the north end I saw a ewe and lamb; at the south end a mature ram — 

 no other fresh signs on the whole mountain. I undertook the needle-in- 

 the-haystack task of hunting high along the crest for the ram, and finally 

 killed him on the third day after seeing him. Also, I picked up a 

 bleached skull of a mature ewe. 



As I had expected, the ram shows the effect of the severe environment. 

 It is a dwarf, the smallest I have ever seen in the United States, Mexico 

 or Alaska. Its skull is very much smaller than skulls from the Gila 

 Range, and shows marked differences. I have Gila skulls here for com- 

 parison. I think the ewe will show corresponding differences. Therefore 

 on El Rosario we have the smallest sheep in America; whether you would 

 record this fact in specific terms I do not know. 



In another letter he says : 



During the long periods between rains — commonly four or five months 

 and sometimes more than eight months — the sheep must live without 

 water for there are no rocks that will hold water more than three or four 

 days. No rain fell between August, 1915, and the time of my visit in 

 March, 1916. The bladder of the ram killed measured two inches and 

 contained only traces of a discolored liquid. 



The ram fell on a very steep slope. I had to spend a long time in 

 building a platform of rocks in order to measure its length and height. 

 Even then these measurements are only approximate. The only positive 

 fact about them is that I was most careful to make them greater than 

 they really were. 



Examination of Sheldon's specimens confirms the correctness 

 of his conviction that the El Rosario animal is a dwarf sheep 

 previously miknown. 



The new form may be characterized as follows: 



Ovis sheldoni sp. nov. 



Type No. 210585, d* adult, U. S. National Museum, Biological Survey 

 Collection. From El Rosario, northern Sonora. Collected March 10, 

 1916, by Charles Sheldon and by him presented to the Biological Survey. 



*New Trails in Mexico, by Carl Lumholtz, p. 316, 1912. 



