02 NATURAL HISTORY OF 



the same enclosure, would be the positions and atti- 

 tude ; and a closer attention would soon convince, that 

 the corresponding members in each, while beautifully 

 formed for their proper uses, could not be employed 

 to perform similar actions, with an equal degree of 

 strength, firmness, or ease. 



Few persons, in the present era, will assert, 



" Men have four legs by nature, 



And that 'tis custom makes them go 

 Erroneously upon but two/' 



While the fact, that no nation in the world assumes any 

 except the erect attitude, will be sufficiently conclusive, 

 without making use of the many arguments which might 

 be drawn from the adaptation of structure. Let us now 

 see how this agrees with the natural gait of the orangs. 

 In man, the limbs, the principal organs of progression, 

 and of maintaining the upright position, are equal in 

 length to the head and trunk together, while the 

 upper extremities are comparatively short. The glutei 

 muscles are the largest in the human body, and the 

 gastronemi, or calf, are of immense power, and ter- 

 minate in a powerful cord, inserted in the extremity 

 of the bone, forming the -heel or os calcis. These, 

 however, would be insufficient, without a surface or 

 base on which the trunk itself could rest ; and we 

 find this supplied by a broad and capacious pelvis, 

 with which the thigh-bones form a right angle, by 

 means of the length of the cervix femoris, or neck 



