242 VERTEBRATE ZOOLOGY 



be wary, for they are excellent food for both man and beast. I 

 have frequently seen young specimens lying in shallow water with 

 only the proboscis-like snout and the dorsally placed eyes protrud- 

 ing above the surface. The body is usually covered over with a 

 film of mud which has been thrown up by rocking the body from 

 side to side and allowing the sediment to settle. When thus cam- 

 ouflaged they are reasonably safe from their enemies. But so swift 

 and alert are the adults that it is unlikely that they would be caught 

 by any of the creatures that inhabit their native waters. Even man 

 with all his equipment for catching animals has the greatest difficulty 

 in securing these tortoises. When one happens to be caught, however, 

 it " keeps its wits about it," as my assistant once said, and is ever on 

 the alert to escape. The captor must be equally wary, for the long 

 neck and strong jaws have an unerring aim quite in contrast with the 

 blind, furious lunge of the " Snapper." The food of the "soft shell" 

 consists chiefly of crayfish and insect larvae, which they swallow whole 

 without rending in pieces. The nest of this species is a rather deep, 

 neatly made, flask-shaped cavity dug in clean, moist sand. The fe- 

 male comes ashore with the greatest caution, usually very early in the 

 morning, and while making the nest stretches the head on high on 

 the lookout for danger. There are from 15 to 25 spherical tough- 

 shelled eggs, placed in several layers, with sand pads between. The 

 completed nest is covered over so neatly that no trace of it is to be 

 seen from the surface. All of the activities of this species of tortoise 

 appear to the writer to indicate a considerably higher order of intel- 

 ligence that that shown by any other chelonian. 



ORDER CROCODILIA 



This order is characterized by its well-proportioned body form, 

 with long tail and well-developed fore and hind limbs; fixed quadrate 

 bone; teeth fixed separately in alveoli. These characters apply not 

 so well to ancestral groups of crocodiles, such as the Pseudosuchia and 

 Eosuchia, as they do to the modern types, the Eusuchia. It is believed 

 that the true crocodiles have been derived from a generalized diap- 

 sidian stock as far back as the middle of the Triassic, and we find 

 true fossil crocodiles during the late Jurassic and a continuous line 

 of them up to the present. 



Structural Characters. The exoskeleton is composed of squarish 

 corneous thickenings, with narrow channels of flexible skin separat- 



