PRONGBUCK 327 



pletely disappeared from both these states. In latitude their range extended from 

 the tropics to the 5-ith parallel ; and within these limits they frequent by choice the 

 open prairie country, avoiding thickly-timbered districts or high naked mountains. 

 That the horns of the prongbuck were shed annually was long 

 and persistently urged by the hunters of Fort Union; but these 

 statements were received with incredulity by naturalists, who scouted the idea. 

 Eventually, however, it was proved to their satisfaction that the hunters were right 

 and they themselves in error. In fully adult individuals, the annual shedding of 

 the horns usually takes place during October, but in the young the horns are 

 retained till January. In the males the horns can be felt as prominences beneath 

 the skin even at birth, and at about four months old they burst through the 

 skin. They are later in making their appearance in the females, and cannot be 

 detected at birth. One of the best accounts of the shedding and replacement 

 of the horns is given by Mr. Caton, from which the following summary is taken. 

 On looking into the hollow of a shed horn, it will be found that the cavity does 

 not extend much above the point of bifurcation ; while it will be also noticed that 

 the interior of the horn contains a number of coarse light-coloured hairs, all of 

 which are firmly attached to its substance, while in the lower part many pass 

 completely through it. The core from which the sheath was cast will also be 

 found to be covered with similar hairs growing from an investing skin; and it 

 will thus be evident that the sheath was more or less completely penetrated by a 

 number of the subjacent hairs, which were of course torn asunder at the time of 

 shedding. Indeed the horn of the prongbuck is in reality nothing more than 

 a mass of agglomerated hairs, and thereby differs markedly from the bovine horn. 



On examining the head of a prongbuck from which the horns have been freshly 

 shed, it will be observed that the summits of the cores are already capped with 

 small new horns, which have evidently commenced their growth considerably before 

 the period of casting, as they reach for several inches above the tips of the cores. 

 The summits of these new horns are perfectly hardened, but lower down they 

 gradually become softer and softer, until they pass into the skin investing the 

 greater part of the core. The condition presented by an animal with newly-growing 

 horns is shown in the woodcut on the following page. 



It is thus clear that as the new horn gradually increased in length above the 

 summit of the core, it must have loosened and carried with it the old sheath, which 

 eventually became completely detached from the core by the breaking and tearing 

 away of the hairs passing from the skin into its substance. When nearly the whole 

 of the hairs were detached or broken, any sudden motion of the animal would 

 doubtless lead to the loss of the horns ; but it does not appear that, at least as a 

 rule, the process is assisted by the animal rubbing its horns against neighbouring 

 objects. In regard to the renovating process, Mr. Caton writes that " when the old 

 horn was cast off, the new one, as we have already seen, had made a considerable 

 growth above the core, which was already tipped with perfected horn, while a section 

 below it was more or less hardened, or partially converted into horn. This inter- 

 vening section gradually moved down the horn, constantly invading the soft skin 

 below, and followed above with perfected horn. All this time the horn was growing 

 in length above the core, and assuming that posterior curvature near its upper part 



