4i6 CLASSIFICATION OF THE EQUID^. 



other about four or five inches apart, so that there is a 

 strip of skin of ordinary thickness running down the croup 

 towards the tail. These pieces of skin are utiUsed, chiefly, 

 for the manufacture of long boots for foreign cavalry 

 officers, by curriers, who dress and pare down the " shell," 

 or hardened layer, until it is almost as smooth as glass, 

 and can consequently take the brilliant polish which is 

 greatly esteemed by these beaux sabreurs. I need hardly 

 say that the leather which is thus employed, is worn inside 

 out. It is both air and water tight. The " shell " is con- 

 nected to the skin so closely that the two form one piece ; 

 although their respective consistencies are different. If a 

 section be made through the hide, their line of union may 

 be readily seen. In the ass, the " shell " is not confined to 

 the skin that covers the pelvis ; but also extends over the 

 ribs, which are consequently not as sensitive to the effects 

 of blows as are those of the horse. The tendency which 

 horses and. [asses have to turn their rump, as the least 

 sensitive part of their anatomy, towards falling rain, cold 

 currents of wind, etc., appears to be due to the feeling of 

 protection to that part, which the presence of the " shell " 

 on each side gives them. 



14. The ass has no tufts of hair at the fetlocks (p. 290). 



15. Messrs. Tegetmeier and Sutherland appear to have 

 been the first to note the difference between the respec- 

 tive periods^of gestation of asses and horses ; the former 

 period being twelve months ; the latter, eleven months 



16. The foot of the horse is mere highly specialized than 

 that of the ass. One of the best-marked evolutionary 

 changes in the equine foot, was the gradual curtailment 

 of its posterior bearing surface (frog .and sole), until, in 

 the horse (Fig. 382), the length of this bearing surface is 

 not much greater than its width, and is included between 

 the heels and the " toe " of the hoof. In the ass, this 

 bearing surface is relatively longer than in the horse, 

 and extends some distance beyond the heels to the rear 

 (Fig. 443). Also, the shape of the foot of the ass, from 



