50(3 THE MECHANICAL FUNCTIONS. 



to give greater velocity to the actions of the 

 muscles, while it at the same time ensures the 

 utmost steadiness and security of motion. 



At the lower extremity of the cannon bone 

 there are two articular surfaces, indicating the 

 originally separate ends of its two component 

 bones. They are for the articulation of the two 

 following bones, which are also very long, and 

 which correspond in situation to the first pha- 

 langes of the fingers and toes. These are fol- 

 lowed by a second and third set of phalanges ; 

 the last of which terminate in hoofs. All rumi- 

 nant quadrupeds have thus a double hoof; a 

 character which is peculiar to this family. 



Thus, then, has Nature moulded the organs of 

 progressive motion in this remarkable tribe of 

 animals to accommodate them to the peculiar 

 conditions of their existence, while she has still 

 preserved their relations to the primitive type of 

 the class to which they belong. Thus has she 

 bestowed upon them the slender and elegant 

 forms, so pleasing to the eye, which characterise 

 the fleetest racer, and has provided for the agile, 

 yet firm and secure movements which they are 

 to exercise in various ways in eluding the obser- 

 vation, and escaping from the pursuit of their 

 stronger and more sagacious foes. This purpose 

 they effect, at one time by rapid flight across 

 extensive tracts of country ; at another, by re- 

 tirement into unfrequented forests, or mountains 



