ORDER OPHIDIA. - 289 



able, some support ribs, and in certain species are more than 

 two hundred in number. While those which do not, and which 

 may be about one hundred and twenty, belong to the tail, 

 and have no connection with the rest of the skeleton. 



Nevertheless, in each of these bones, whose assemblage 

 constitutes almost the entire skeleton, we can distinguish a 

 body, spinous, articular, and transverse apophyses. 



The first of these apophyses, which predominate all along 

 the back, are separated from each other in the boas, while in 

 the crotali they are so broad, that they appear to touch by 

 their next edges. On the vertebrae of the tail, they are 

 replaced by tubercles, in all the ophidians in general. 



The articular apophyses are imbricated, and cover each 

 other after the manner of tiles. 



The upper face of the body, thin, bears a very sharp spine 

 directed towards the tail, and which limits the movement 

 only when it might produce luxation, without otherwise 

 constraining it. But its anterior face presents an hemisphe- 

 rical tubercle, which is received in a corresponding cavity 

 of the preceding vertebra, so that each vertebra is articulated 

 by enarthrosis, with that which follows and with that which 

 precedes. In fact, in plainer language, this articulation 

 resembles that of the knee, and easily explains the peculiar 

 nature of the motions executed by the ophidians. 



Although articulated by a projecting condyle, with three 

 facettes disposed trefoil-like, yet the head, in the ophidians, 

 is not more moveable on the atlas, than the other vertebras 

 are upon each other. 



Like that of all reptiles the sensibility of these animals 

 is obtuse, and this remarkable attribute of the vital power 

 may be apparently destroyed in them, often during a long 

 period, as in winter, when they fall into an absolute lethargy. 

 But on the other hand, their irritability is truly astonishing; 

 their heart will still palpitate a long time after it has been 



VOL. IX. u 



