OSSEOUS SYSTEM OF MAMMALIA. 29 



tude, is performed, are proportionate to their office : with the expansive 

 pelvis, we find, also, the glutaei muscles assuming a figure and degree of 

 development found in no other animal except Man. The mass which 

 they form, not only braces the thigh-bone firmly, in its perpendicular 

 bearing from the ilium, when he stands erect or walks, not only gives 

 firmness to the femur, in supporting the weight of the trunk, but enables 

 him to sit upright in a state of rest, while awake, the organs of the senses of 

 sight, smell, and hearing still preserving their advantageous direction ; 

 but which direction, were he obliged to lie down like the quadrupedal 

 brute, in order to repose, would be so prone, as to militate against the 

 express uses to which Man, as an intellectual being, applies them. To 

 such a being the advantages of an upright sitting posture (a posture not 

 even allowed to the Simiae) is self-evident. In the Simiae the glutaei 

 differ greatly in their arrangement from those of Man. In the former, 

 the elongation of the os ilium renders the glutaeus medius and minimus 

 larger ; while the muscle analogous to the glutaeus maximus is the smallest 

 of the three. The Carnivora and Rodentia exhibit the same proportional 

 diminution of the glutasus maximus. " Solus homo," writes Adrian 

 Spigel, " ex omnibus animalibus commode sedet ; cui carnosae et magnae 

 nates contigere, et pro subsellio, pulvinarique tomento repleto inserviunt, 

 ut citra molestiam sedendo, cogitationibus rerum divinarum animum rec- 

 tius applicare possit." 



The extensor muscles, and the flexor muscles of the knee, in lower 

 animals, present, in their relative proportions, the converse to what is 

 found in Man. In the lower animals, not only are the flexors of the knee 

 stronger than in Man, but inserted so much lower down the tibia, as to 

 retain the knee in a naturally bent condition ; while the extensors are 

 weaker than in Man, who requires them to be powerful, both to throw 

 the leg forward and upward, in walking or running ; also, to keep the tibia 

 firm in standing, so that the knee-joint may not totter, or give way. 



The muscles which lift the human heel are so large as to form pro- 

 minent calves, a characteristic peculiar to Man ; and which is in itself 

 a sufficient proof that the legs are destined to support and move the 

 whole machine.* 



* Dr. Arnott has made some very interesting observations on the muscles which constitute the 

 human calves. " The heel," he says, " by projecting so far backward, is a long lever for the strong 

 muscles which form the calf of the leg, and terminate in the tendo Achillis, to act by. These muscles, 

 by drawing at the heel, lift the body, in standing on the toes, in walking, dancing, &c. In the Negro 

 foot, the heel is so long as to be ugly in European estimation, and its great length rendering the effort 

 of smaller muscles sufficient for the various purposes, the calf of the leg in the Negro is smaller in 

 proportion than in other races of men. In a graceful human step, the heel is always raised before 

 the foot is lifted from the ground, as if the foot were part of a wheel rolling forward, and the weight 

 of the body rests, for a time, on the forepart of the foot and toes. The muscles forming the calf, 

 lift the heel, by drawing at the tendo Achillis, and produce a bending of the foot in a corresponding 

 degree. But where strong wooden shoes are used, or any shoe that will not yield nor allow this bend- 

 ing of the foot, the heel, in walking, is not raised at all, until the whole foot rises with it ; so that the 

 muscles of the calf are scarcely used, and, in consequence, soon dwindle in size, and almost disappear. 



