SEEING A SNAKE EEED. 31 



the case in a lesser degree with the palate bones, and the 

 upper jaw-bones, all six being furnished with long, fine, re- 

 curved, close-set teeth, adapted for grasping and holding, 

 but not for dividing or for mastication in any way. 



For, as we have seen, if a snake were to open Its mouth 

 one moment for the purpose of what we call biting, the prey 

 would escape. In addition to a very unusual length, the 

 lower jaw Is joined to the skull by an extra bone, — one 

 which Is not found In mammals, but only, I think, In birds, — 

 a long 'tympanic' bone, which forms an elbow, and 

 permits of that wide expansion of the throat necessary for 

 the passage of such large undivided prey. 



The illustration of the skeleton of a cobra, on p. 33, 

 will enable the student to distinguish the principal 

 head-bones. There Is so much similarity of construction 

 throughout the whole ophidian families that a cobra Is 

 chosen here, because the unusually long anterior ribs which 

 form the hood can be obsei-ved, and the expansion of 

 which Is described elsewhere. The longer teeth in the upper 

 jaw are here fangs ; the inclination of the other rows 

 of teeth and the bones sufficiently Illustrate those of the 

 non-venomous kinds generally, such as the little rlno- 

 snake that has just swallowed his frog. A few of the 

 larger constricting snakes possess an additional bone — 

 an Intermaxillaiy in front between the upper jaws, very 

 small, yet sometimes furnished with two or four teeth, 

 thus facilitating the expansion of the jaws as well as the 

 retention of the food. 



It is this adaptive development of head-bones that enabled 

 Coluber natrix to turn his frog round to a more convenient 



