84: SKULL OF POISONOUS SERPENTS. 



witti the rest in succession — this movement of protrac- 

 tion being almost the only one of which they are suscep- 

 tible whilst stretched apart to the utmost by the bulk 



of the animal encompassed by 

 Fig- 1^- them ; thus, by their successive 



movements, it is slowly and 



spirally introduced into the 



wide gullet. 



The bones of the mouth, in 

 SKULL OF A POISONOUS SNAKE, tlic poisouous scrpeuts, have 



characters distinct from those 

 of the constricting serpents. These characters consist 

 chiefly in the modification of form and attachments of 

 the superior maxillary bone (Fig. 15), 21, which is mov- 

 ably articulated to the palatine, ectopterygoid, and lachry- 

 mal bones; but chiefly supported by the latter; which 

 presents the form of a short, strong, three-sided pedicle, 

 extending from the anterior external angle of the frontal 

 to the anterior and upper part of the maxillary. The 

 articular surface of the maxillary is slightly concave, of 

 an oval shape ; the surface articulating with the ectopte- 

 rygoid on the posterior and upper part of the maxillary 

 is smaller and convex. The maxillary bone is pushed 

 forward and rotated upon the lachrjanal joint by the ad- 

 vance of the ectopterygoids, which are associated with 

 the movements of the tympanic pedicle of the lower jaw 

 by means of the true pterygoid bones. The premaxil- 

 lary bone (Fig. 13), 22, is edentulous. A single, long, 

 perforated poison-fang is anch3dosed to the right maxil- 

 lary, and sometimes two similar fangs, as in the cobra 

 figured in Cut 13. The palatine bones have four or five, 

 and the pterygoids from eight to ten small, imperforate, 

 pointed, and recurved teeth. The frontal bones are 



