SPECIES AND BREEDS. 35 



mon physiological test of specific difference, 

 the incapacity, namely, of the cross to propagate, 

 does not hold good as applied to this animal. 1 

 The skeletons of the two species are distinguish- 

 able, if at all, only by a slight difference of pro- 

 portion ; and the visceral structure being sub- 

 stantially the same in both, 2 the only foundation 

 for a specific distinction appears to be in the 

 number of humps. In the living animal, the 

 species are readily distinguished by this outward 

 peculiarity ; and besides this obvious difference, 

 the Bactrian is shorter limbed and much more 

 hairy than the Arabian camel. Some writers 

 describe the Bactrian as upon the whole smaller 

 and weaker than the Arabian ; but as others 

 state the contrary, the difference in this respect 

 is probably not great. It seems well settled that 

 in countries where the two species exist together, 

 the cross, though inferior to the dromedary in 

 speed, is found to be a more powerful, and for 

 general purposes, a more serviceable animal than 

 either of the unmixed races, as possessing in a 

 good degree the most valuable properties of 

 both. 3 



1 Hitter, Erdkundc, xiu. 659. 



2 The stomach of the Arabian camel as described by Jack- 

 son, (see chapter vi. post,) appears to differ considerably 

 from that of the Bactrian dissected by Sir Everard Home. 



3 See a valuable paper, extracted from the notes of Gen- 



