5^4 OPHIDIA 



CHAP. 



to investigate anything. In spite of the protractility of the 

 tongue, the hyoid apparatus is very small ; the hyoid arches 

 themselves are reduced to mere vestiges near the base of the 

 first and only branchial arches, which are thread-like and extend 

 backwards down the throat. 



The trachea is very long, and opens far forwards in the 

 mouth ; it can be slightly protruded between the two 

 halves of the lower jaw so as not to be l)locked during the act 

 of swallowing. This is a laborious process. The snake, having 

 got hold of its prey with its teeth, generally shifts it into the 

 most convenient position, in order to swallow the head first. One 

 half of the mandible is then pushed forwards, then the other 

 half; the recurved teeth afford the necessary hold, and the 

 snake, little by little, draws its mouth-cavity, and later on itself, 

 over the prey. In fact, it literally gets outside it. Sometimes 

 with a large victim this process may last for hours ; the whole 

 mouth and head become painfully distended and the veins swollen 

 almost to bursting. The snake pushes the prey against a stone or 

 other obstacle, rests awhile quite exhausted, and begins afresh. 

 At last the bulk of the prey has passed the mouth, the skin of 

 the neck is stretched to the utmost, the scales being separated 

 by wide interstices, the ribs work spasmodically, the victim is 

 pressed into the shape of a sausage, and the deed is done. In 

 order to assist deglutition there is a great amount of salivation, 

 but the often-heard story that Snakes cover their prey with 

 saliva before they swallow it, is a fable, or based upon faulty 

 observation, snakes sometimes beim^ forced to disgorge the 

 half-swallowed prey, which, in such a case, is covered with slime. 

 One of my tame snakes had swallowed a frog on my table when 

 a friend entered ^the room. The snake was frightened, jumped 

 on to the ground, striking it with its full belly, and thereby 

 hurting the frog, which squeaked loudly, whereupon the snake 

 reversed its mechanism and the frog hopped away, none the 

 worse for its terrible experience. 



In correlation with the elongated narrow space of the body- 

 cavity the lungs are not equally developed, the left being much 

 smaller than the right. The latter is a very thin-walled, hollow 

 bag, and the posterior half or third scarcely contains any of the 

 honey-coml)-like resjnratory " cells," but acts merely as a reservoir 

 of air. 



