160 MUSCULAR SYSTEM. 



feet species, is attached by muscles to the trunk, though not 

 yet destined to support atlantal extremities, and the internal 

 lateral muscles passing from the vertebras to the ribs, form 

 the rudiment of a diaphragm. 



The muscles of saurian reptiles are more numerous and 

 complicated than in ophidia, because they possess members 

 for progressive motion, adapted sometimes for swimming 

 and sometimes for running or climbing, and sometimes these 

 animals are organized for moving through the air. The 

 stratified disposition of the great lateral muscles of the 

 trunk, so conspicuous in the fishes, the urodelous amphibia, 

 and even in the serpents, is less marked in the comparatively 

 motionless bodies of the saurian reptiles, excepting in those 

 which have scarcely yet the members developed. This ar- 

 rangement of the muscles, in regular series around the ver- 

 tebrae, is still continued in the coccygeal region of the co- 

 lumn, which, together with the neck, is more flexible than 

 in the ophidia. Several muscles of the face are wanting on 

 the rough and hard head of the crocodilian reptiles, their 

 temporal and masseter muscles are protected externally by 

 the temporal, frontal, and malar bones, and their insertions 

 are on the inner surface of the lower jaw, the muscles of the 

 os hyoides, and those which connect the head with the trunk 

 are distinct and powerful, as in most reptiles, and those of 

 the tail, which is nearly as thick as the trunk, are of great 

 strength, for the lateral motions of that part in swimming. 

 The short muscular legs of these animals, diverging out- 

 wards, scarcely raise the trunk oif the ground, on which the 

 saurians, and most other reptiles rest the body, when not 

 in actual progression. The legs, in these aquatic sauria, are 

 compressed in form, to facilitate their advancement in the 

 water, as in web-footed birds, and they have strong extensor 

 muscles, to give impulse to their webbed feet. More nimble 

 movements, and more light and pliant forms of the locomotive 

 organs and of the wholebody are seen in most of the terrestrial, 

 climbing, long-toed,and long-tailed lacertine sauria. The direc- 

 tion outwards of the humerus and femur weakens the limbs, 

 and adapts them better for climbing and prehension than for 

 support or for running. The long fingers and toes, with 

 their powerful flexors in the lacertine sauria, adapt them for 

 climbing on trees in pursuit of their prey. The opposed 



