DIFFERENCES BETWEEN ASSES AND HORSES. 413 



allowed to grow. The difference in the mane is due to 

 the length of the hairs of the part. In almost all breeds 

 of horses, the hairs of the tail grow long from the root of 

 the dock. In the ass, they do so only as they approach 

 the end of the dock. 



3. As a rule, the ass has five loin vertebrae, and the 

 horse six (p. 422). I have never heard of an instance, in 





Fig. 443. — Off fore foot of donkey. 



the domestic ass, of the number of these bones exceeding 

 five. I believe that the normal number in zebras is five. 

 If, however, we examine the skeleton of the Mountain Zebra 

 which is in the Museum of the R.C.S. Lincoln's Inn Fields, 

 we shall see that it has six loin vertebrae. The num.ber of 

 these bones is subject to variation in all vertebrates. 



4. In the horse, the lachrymal duct, which is the canal 

 that conveys tears from the eye on each respective side 



