HYBRIDS. 



307 



that part, which the presence of the " shell " on each side 

 gives him. 



Professor Huxley remarks that asses form a distinct 

 species from horses; because "all asses have tufted tails and 

 have callosities only on the inner side of the fore legs. If 

 animals were discovered having the general characters of the 

 horse, but sometimes with callosities only on the fore legs 

 and more or less tufted tails ; or animals having the general 

 characters of the ass, but with more or less bushy tails and 

 sometimes with callosities on both pairs of legs, besides being 

 intermediate in other respects, the two species would have to 

 be merged into one. They could no longer be regarded as 

 morphologically distinct species, for they would not be dis- 

 tinctly definable one from the other." When Professor 

 Huxley wrote this, he was evidently unaware that the horse 

 has not invariably callosities on all four legs {see p. 2 1 7). 



Hybrids between the Horse and Ass. — Neither the 

 mule (the produce of the jackass and mare), nor the hinny or 

 jennet (the cross • between the horse and the she-ass), is 

 fertile, either among themselves, or with other members of 

 the horse family. Those animals which have been mistaken 

 by superficial observers as fertile mules, have been, I venture 

 to say, in most cases the offspring of mares that have 

 previously bred to donkeys, and have endowed their young 

 with some of the characteristics of their former asinine lovers. 

 Both the mule and the jennet respectively "take after" their 

 dam in size ; and their sire, in appearance and disposition. 



I know nothing respecting the question of the fertility of 

 the respective crosses between the different kinds of asses, 

 true or striped, 



X 2 



