THE REPTILES 187 
not concerned with the protection of the brain. In the 
reptiles the lower jaw does not unite directly with the 
skull, as in the higher animals, but to an intermediate 
bone, the quadrate, which is attached to the skull. In the 
snakes these unions are made by means of elastic liga- 
ments. The two halves of the lower jaw are also held 
Fic. 112.—Blacksnake (Bascanion constrictor). Photograph by W. H. FIsuer. 
together by a similar band, so that the entire palate and 
lower jaw are loosely hung together. This enables the 
snake to distend its mouth and throat to an extraordinary 
degree, and to swallow frogs and toads but slightly smaller 
than itself. Where the prey is of relatively small size, the 
halves of the lower jaw alternate with each other in pulling 
backward, thus drawing the food down the throat. The 
food is never masticated. The teeth are usually small and 
recurved, and serve only to hold the food until it may be 
swallowed. The latter process is facilitated by the copious 
secretion of the. salivary glands, which become very active 
at this time. 
A further character of the snakes is the absence exter- 
