9i 



TEE BONES. 



diarthrodial facets on its extremities. It also differs from the other vertebrae by 

 the shortness of its spinous process, which terminates in a point ; by the size and 

 prominence ,of its articular processes ; and by the depth of its notches. The 

 last vertebra never has facets on the contour of its posterior cavity. 



Ass. — Besides the smaller volume of the vertebrse, the following differential 

 characters will serve to distinguish these bones in this animal : 1. The spinous 

 processes, as far as the tenth vertebra, are a little more inclined backwards than 



Fig. 20. 



A DORSAL VERTEBRA OF THE HORSE AND ASS (THE ELEVENTH). 



A, Vertebra of the Horse {anterior face). 1, Head ; 2, spinous process ; 

 3, 3, transverse processes. 



B, Vertebra of the Ass (anterior face). Same description as for the horse. 

 a', Vertebra of the Horse (lateral face). 1, Head ; 2, spinous process ; 



3, transverse process. 

 b', Vertebra of the Ass (lateral face). Same description as for the horse. 



in the Horse, while the inclination forward of the latter is equally marked ; the 

 anterior part of the summit of the spinous process is in contact with a horizontal 

 plane, when the three last vertebrae of the Ass are laid on their anterior portion. 

 2. From the first to the tenth, the summit of the transverse processes lies behind 

 the margin of the anterior articular facets in the Ass, while it is beyond them 

 from the fourth in the Horse. From the eleventh to the thirteenth, the projection 

 of the transverse processes is equal to that of the anterior articular facets in the 



