204 WATER REPTILES OF THE PAST AND PRESENT 



whole, the crocodiles and alligators must tear their food to pieces, 

 which they do by quick, strong Jerks from side to side, aided by the 

 powerful tail; or they may twist off a limb or some other part of 

 their victims by a rapid rotation of the whole body, two assisting in 

 this operation, rotating in opposite directions. 



Living crocodiles lay from twenty to sixty eggs, according to the 

 species; these eggs are sometimes the size of a goose egg, and are 

 covered with a hard shell. They are laid either in a deep excava- 

 tion in the sand and covered over by the parent; or under leaves 

 and straw. The female remains on guard until the eggs are 

 hatched, of which she is apprized, it is said, by a pecuUar noise 

 uttered by the partly imprisoned young. She thereupon reopens 

 the nest, and guides her hberated infants to the water, where she 

 leaves them to their fate. Whether this remarkable habit is one 

 that has been acquired in recent times or not is uncertain, but 

 because it has been observed in a number of unrelated forms, it is 

 probable that the instinct is of long inheritance, and may account 

 for certain pecuharities of structure in some of the ancient members 

 of the order. Doubtless the habit arose because of the unpro- 

 tected places in which the eggs are necessarily laid on the shores and 

 beaches, and because the eggs are comparatively so few in number. 

 The sea-turtles likewise lay their eggs in hollows scooped out of the 

 sand of the beaches, but the parents give no further care to their 

 eggs, nor to their newly hatched offspring, a neglect which is com- 

 pensated for by the much larger number of eggs they lay, because 

 of which the chances are much greater that a few wiU survive the 

 more numerous vicissitudes to which the eggs and young turtles 

 are exposed. 



ANCIENT CROCODILES, MESOSUCHIA 



The name Mesosuchia, meaning "middle crocodiles," by which 

 the ancient members of the Crocodiha have generally been known, 

 was given by Huxley in the behef that they were intermediate 

 between the "true" or modern crocodiles and an ancient group 

 which he united with the order under the name "Parasuchia." A 

 fuller and better knowledge of the members of this last group has 

 proved very conclusively that they are really less allied to the croc- 

 odiles than are some other orders of reptiles, the dinosaurs for 

 instance, and should be properly classed by themselves as a distinct 



