REPTILIA. 555 



of the scapular apparatus has not been as yet decidedly pointed out ; 

 there are, however, three branches, probably representing the Sca- 

 pula, the Clavicle, and the Coracoid bone ; but, in the construction 

 of the pelvis, the Ilium, the Ischium, and the Pubis are identified 

 with facility. 



(610.) The muscular movements of Reptiles are ordinarily 

 slow and languid, a circumstance which no doubt depends upon 

 the impurity of their blood consequent on the imperfect manner in 

 which the circulating fluid is exposed to the influences of respir- 

 ation. The muscles of these animals are, however, peculiarly tena- 

 cious of life, and preserve their irritability and power of contraction 

 for an astonishing length of time after they have even been separated 

 from the body. The muscles of a Turtle will continue to live for 

 days after the creature has been decapitated ; and the heart will 

 still contract, when irritated, even many hours after its removal. 



But, perhaps, the most interesting phenomenon connected with 

 the muscular system of the Reptilia, is the progressive develope- 

 ment of entirely different sets of muscles as the metamorphosis 

 goes on by which they are converted from their earliest fish- condi- 

 tion to their mature and perfect state. This series of changes, 

 which doubtless takes place in all the higher Vertebrata, is well 

 exemplified in the tadpole of the Frog or Toad, and the different 

 phases of developement are in such creatures easily investigated. 

 At first the tadpole presents the muscular structure of a fish, both in 

 the muscles of the expanded and vertical tail, and in those of the 

 branchial apparatus. As growth proceeds, the broad muscles of 

 the abdomen become developed, and ultimately those of the 

 limbs are superadded as those members successively make their ap- 

 pearance ; the muscles of the shoulder and pelvic region being first 

 recognisable, and subsequently those of the legs and feet. In the 

 mean time, as the abdominal muscles, and those of the extremities, 

 become gradually perfected, those peculiar to the fish-state are 

 rapidly removed : the broad tail becomes atrophied and absorbed, 

 diminishing in length nearly at the rate of a line a day ; the 

 flaky lateral muscles of the caudal region disappear altogether ; 

 and, moreover, the entire muscular apparatus of the branchial and 

 hyoid systems is altered as the character of the respiratory organs 

 becomes changed, in a manner to be explained hereafter, from 

 the aquatic to the aerial condition. 



(611.) As Reptiles, for the most part, must from necessity 

 swallow their prey entire, organs of taste would be scarcely more 



