THE MULES. 339 



demand not to be made more absolute than is 

 necessary, and should be limited in the application 

 to the true phenomena of each case, for these vary 

 exceedingly upon the slightest discrepancies between 

 osculating or nearly osculating animals, some hy- 

 brids being sterile, others reproductive, though with 

 an apparent decreasing power of fertility, and some 

 where there is no observable check in progenitive- 

 ness, or where it is soon obliterated. Such we 

 conceive to be the true horses here described, the 

 two species of camel, the goat and sheep, and most 

 if not all the species of both; we might add the 

 domestic cats, including the blue or chartreux, ori- 

 ginally belonging to a distinct feline group; the 

 Bengal cat described by Pennant, of a second, and 

 the tortoiseshell cat, to all appearance sprung from a 

 third group originally indigenous in South America, 

 and still sufficiently aberrant to produce in the do- 

 mestic commixture males with the greatest rarity, 

 thouoh the distinctive character is so strong that the 

 females alone are competent to preserve it. Frederick 

 Cuvier rejects the existence of mules where neither 

 of the parents are domesticated, but we know wild 

 mammalia under restraint are likewise in the pre- 

 dicament as well as several species of birds in a 

 state of liberty, such as Gallinacea and several Meru- 

 lidae and Fringillid^e. We question the reserve of 

 all polygamous ruminants and of some pachyder- 

 mata ; all those that expel a proportion of the males 

 from the herd and that can find approximating 

 species. From personal inquiry among those who. 



