MAMMALIA SOLIPEDA. , 357 



course, is single, likewise; there is, also, a small bone, con- 

 nected with the last, and called the shuttle hone. To the 

 cannon bone are joined, behind, and on the side, two much 

 shorter and very slender bones, which are rudiments of the 

 other metacarpal bones. They have been termed the sty- 

 loid, or splint hones; and are generally united by ossifica- 

 tion with the cannon bone. The scapula of the horse is 

 very narrow, and placed very nearly in a straight line with 

 the humerus; which latter bone is very short, and scarcely 

 descends below the line of the chest. The thigh-bone is also 

 unusually short. The muscles, which extend the joint, and 'UJk 

 throw the thigh backwards, in kicking, are particularly pow- 

 erful. This is the natural defensive action of the horse: and 

 its force is increased by a particular process with which the 

 bone is furnished, and which has the form of a strong curved 

 spine, situated on the outside, and opposite to the lesser tro- 

 chanter,* giving to the muscles the advantage of a long le- 

 ver. The cervical vertebrae have only short spinous pro- 

 cesses, that they might not interfere with the motions of the 

 neck. In the vertebrae of the back, on the other hand, these 

 processes are remarkably long, especially at the part where 

 the shoulder rests; their projection constituting what is 

 called the Withers. 



§ 7. Pachydermata, 



From the horse we pass, by a natural transition, to the 

 Pachydermata^ a small group of animals interesting by their 

 peculiarities, and by their being remnants of a very extensive 

 tribe, which formerly inhabited the earth, but have now al- 

 most entirely disappeared. Although they feed upon grass, 

 they do not ruminate, nor are they cloven-footed. They are, 

 for the most part, huge and unwieldy animals, with thick in- 

 teguments, rendered tough by a large mass of condensed cel- 

 lular substance, which forms the chief defensive armour of 



* This process has been termed ^\q, jiroccssus recurvatusfemoris. 



