216 Dr. N. Severtzoff on the Mammals of Turkestan. 



the skull of different species ankylose at different ages ; 

 and this corresponds with the development of the horns — that 

 iSj with the specific differences in their size and weight. 



The larger the horns are, the sooner do the different bones 

 of the skull ankylose, of which I convinced myself in com- 

 paring 0. PoUij 0. Hemsu, and 0. Karelini, all of the same 

 age, viz. about four to five years ; consequently it may be 

 said that the ankylosis of the different parts of the skull is in 

 proportion to the size of the horns. This is shown also in 

 the above list of measurements. 



The same skulls also show that the horns begin to grow 

 massive and the forehead to develop only after the animal 

 becomes adult — namely, when it attains an age of four and a 

 half years, which period of its development is also marked 

 by other circumstances. In examining the skulls which, 

 one often finds among the rocks and even in the plains about 

 Narin and Aksay, I noticed that most of them belonged (ac- 

 cording to the horns) to beasts of from four to six years of age, 

 very seldom to younger or older individuals, and exclusively 

 to the male sex. This shows that these skulls belonged to 

 sheep which did not die on account of their great age, but from 

 violence ; nor is it likely that they were killed by wolves, as 

 these latter would most probably concentrate their attacks 

 upon the young or female animals. Here the question 

 arises, why do they die principally at that age^ and only male 

 specimens ? 



The answer to this is best given by the consideration of the 

 locality where the skulls are usually found — namely, in pairs 

 under steep cliffs, from which the animals in all probability fell 

 and killed themselves whilst fighting : this would, of course, 

 be most generally the case with the young, weak-horned males, 

 which had only lately reached an adult age. 



The females and young do not fight ; and should an old and 

 a young male have an encounter, the former, in most cases, 

 naturally conquers. 



In all cases where two skulls are found together, one is 

 older than the other ; this shows that whilst fighting not 

 only the one that was beaten fell from the cliff, but also that 

 its stronger antagonist overbalanced itself whilst charging 

 its enemy. 



I have also found single skulls, and that not rarely ; these 

 belonged to younger males (generally, however, over four 

 years of age) ; they show that the victor was an old male with 

 much larger horns than the animal killed. 



About Narin the skulls are generally found under preci- 

 pices ; a few, however, also on the plains. The latter have 



