CLASSIFICATION OF EEPTILES. 675 



scale-clad serpent makes its way in either element with equal facility, 

 and walks or leaps, or climbs or swims, at will. Destitute of any pre- 

 hensile members, it seizes and devours the strongest and most active 

 prey : it binds its victim in a living rope ; or, with a single scratch in- 

 flicted by its venomed fangs, speedily destroys the stoutest assailant. 



(1875.) The transition from the OPHTDIA to the Lizards (SAFKIA), 

 composing the third order of Reptiles, is very gradually accomplished 

 by several intermediate forms, in which the first buddings of legs make 

 their appearance ; and these locomotive organs, becoming more and more 

 completely developed in other genera, at length conduct us from the 

 flexible and apodous Serpents to the strong and four-footed Reptiles 

 which are the types of the Saurian division. The progressive develop- 

 ment of the locomotive extremities is not a little curious : even among 

 some of the Serpents properly so called, as, for example, in the Anguis 

 fragilis of our own country, the rudiments of these limbs may be de- 

 tected beneath the skin ; more especially those of the hinder extremity, 

 wherein a little pelvis and femur may be distinctly recognized, while a 

 minute sternum, clavicle, and scapula indicate the first appearance of 

 the thoracic legs. 



(1876.) In Bimanes, the lowest of the Saurian genera, two little feet, 

 each provided with four toes, are appended to the framework of the 

 shoulder ; and in Seps, which equally possesses the body of a serpent, 

 all four extremities first make their appearance externally. As the legs 

 become increased in their relative size and importance, the trunk is pro- 

 portionately shortened and its flexibility diminished, until at length we 

 are conducted, almost by imperceptible gradations, to the strong and 

 voracious Crocodiles, the most perfect of the Reptile families. 



(1877.) The fourth order of Reptiles (CHELONTA) comprises a series 

 of animals of most anomalous conformation, in which the greater part 

 of the skeleton is brought quite to the exterior of the body, and the 

 limbs are absolutely enclosed within the cavity formed by the ribs. Such 

 are the Tortoises and the Turtles ; but as we shall describe the anatomy 

 of these animals more at length hereafter, we need only in this place 

 point out to the reader their outward form and general appearance. 



(1878.) Commencing our researches concerning the internal organiza- 

 tion of this extensive class by examining the osteology of the Reptilia, 

 we shall, as we have hitherto done, select one skeleton for special ex- " 

 amination ; and afterwards, taking that as a standard of comparison, 

 observe the most conspicuous modifications of structure met with in the 

 different divisions of this important group. 



(1879.) The skeleton we choose for particular description is that of 

 the Crocodile, one of the most interesting that can possibly be offered to 

 the contemplation of the comparative anatomist, inasmuch as it exhibits, 

 developed to a medium extent, a greater number of the elements which 

 we have supposed to enter into the composition of a perfect or typical 



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