56 THE STORY OF REPTILE LIFE. 



the body is submerged. In this way prey can 

 be approached unsuspected. 



The external ear, too, has been directly modi- 

 fied in accordance with the peculiar habits of the 

 animal. Its aperture lies in a deep recess over- 

 hung by a flap of skin provided with muscles, 

 which by their contraction close the aperture 

 and prevent the inrush of water. Like the eyes 

 and nostrils, the aperture of the ear is on the 

 surface of the skull, so that hearing as well as 

 sight and smell is possible when the animal is 

 submerged. 



The tongue is large, and fixed to the floor of 

 the mouth, so that it can be raised, but not pro- 

 truded as in lizards. Its surface is covered with 

 numerous tiny wart-like processes, which form 

 the centres of touch and taste. The peculiar 

 fleshy fold which runs across the back of the 

 tongue, and the part it plays in the breathing of 

 the creature when in the water, we have already 

 described (p. 48). 



The lungs have attained a high degree of per- 

 fection, and resemble those of birds. They differ, 

 however, both from those of the birds and those 

 of the tortoises in that, instead of being attached 

 to the roof of the chest cavity, they are quite 

 free. 



The stomach and heart demand a passing 

 notice, inasmuch as both these organs are more 

 highly developed than in other reptiles. 



The stomach seems peculiarly small, when we 

 remember that these huge creatures can swallow 

 very large animals, man himself sometimes fall- 

 ing a victim. Large prey is, however, not 



