CONGENERS. 337 



while in all other respects they exactly correspond, and no ra- 

 tional doubt should exist of their specific identity. The mule 

 deer in the Rocky Mountains is four times as large as in Lower 

 California, which difference is also supplemented by the fact that 

 the change in the antler is quite as great, for on all of the small 

 variety the antler has ceased to be bifurcated, but presents a 

 spike like that of the yearling deer of the north ; or if ever bi- 

 furcated that feature is as rare as on the first antlers of the bet- 

 ter developed variety of the north, and yet I do not hesitate to 

 rank them in the same species from their exact similitude in all 

 other respects, according to the reliable information I have re- 

 ceived of them. With the same propriety might we deny that 

 the P'uegian and the Patagonian are of the same species. 



In considering this question of specific identity we should by 

 no means forget that these animals freely interbreed whenever 

 they have opportunity, and their progeny proves as fertile as 

 either of the parents, as has been shown in the article on Hy- 

 bridity. While this should not be considered as conclusive evi- 

 dence of specific identity, it is important cumulative evidence in 

 that direction. If in the wild state in the forest it were found 

 that the sexes showed the same inclination for each other which 

 they show for the opposite sex of their own varieties, this would 

 add vastly to the weight of the evidence and would make out a 

 very strong primd facie case at least ; for, as is shown in another 

 place, the sexes of separate species have a natural sexual aversion 

 for each other which is more marked in the female, and although 

 this no doubt may be sometimes overcome in the wild state and 

 without constraint, and so hybrids produced voluntarily, probably 

 if the truth could be known we should find that the female re- 

 ceived the embraces of the male only when she could not find a 

 male of her own species. After years of experimenting with as 

 great facilities as are likely to be often enjoj^ed, I at least have 

 been unable to obtain a hybrid under other conditions, and even 

 when no proper male has been on any part of the grounds suc- 

 cess has very rarely attended my efforts, as is more fully shown 

 in another place. 



After the best investigation and consideration I have been 

 able to give the subject — and my opportunities have not been 

 stinted, — I am inclined to fall back into the ranks of those nat- 

 uralists who first compared the two animals, who failed to find 

 sufficient differences to justify the erection of a new species to 

 accommodate the new variety found on this continent, and I 



