164 



OPHIDIA. — BOAD^. 



the palate are two rows of similar teeth: there 

 are no poison-fangs. The hind head is more or 

 less bulging, the body, swelling towards the 

 middle, somewhat compressed, not very length- 

 ened, tapering to the tail, which is short and 

 prehensile. One lung is but half shorter than 

 the other. The body is clothed with imbricated 

 scales, as is also the head, — at least, the hind head : 

 the under surface of the body and tail, however, 

 is covered with scaly transverse plates, arranged 

 in a single series on the body ; but on the tail, 

 single in some genera, and in others double. 



But that which is most characteristic of the 

 Boadce is the presence of tw^o hooks or spurs, 

 situated one on each side of the vent. These 

 are undoubtedly of great use to the reptile, as 

 helping the prehensile tail to maintain a firm hold 



VENT AND HOOK OP BOA. 



on the branch of a tree, from which the long 

 body depends, with the head bent up a little 

 above the ground, watching for the approach 

 of prey. But these spurs are undoubtedly the 

 rudiments of posterior limbs, the bones of which, 

 very minute and imperfect, it is true, are detected 



