166 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



replaced when lost. There are a number of small teeth within 

 the hollow base of each tooth ready to grow up when the 

 outermost one is lost. In one specimen I observed it was 

 a question of some weeks. Crocodiles have fifteen lower, 

 and seventeen or eighteen upper teeth on each side. 

 Alligators and Caimans have more — seventeen to twenty- 

 two in the lower, and seventeen to twenty upper teeth on 

 each side. Gavials have over a hundred ivories in their 

 mouths. 



These creatures are admirably adapted for holding 

 their own in the struggle for existence ; their weapons of 

 attack being the jaws bristling with teeth, and the massive 

 powerful tails. The upper surfaces of these reptiles are 

 protected by strong horny shields, underneath which are 

 plates of bone. The armour is arranged in rows of from 

 four to six or eight deep on the back, diminishing over the 

 tails to four rows, of which the two external series unite 

 about half-way down to form the serrated crest. They 

 have also scattered, sometimes keeled, shields on the sides 

 of the body. Under the root of the tail is a longitudinal 

 Cloaca. 



They are sensitive to the slightest touch over their 

 heads, dorsal and caudal scutes, and can reach any part 

 of their bodies with their legs for scratching purposes. 

 The limbs have a free range of movement. If food gets 

 fixed between the teeth and cannot be dislodged by 

 shaking, the hinder limb of the same side is brought up 

 and removes it. The head, neck, and upper three-fourths 

 of the body can also be reached by the same legs ; the 

 posterior fourth is usually managed by the front pair of 

 limbs. If the cutaneous irritation persists too long, the 

 affected area is vigorously rubbed in a downward direction 

 by the palmar or plantar surfaces. It is interesting to 

 note that the legs can be so turned back that these surfaces 



