VIII INTRODUCTION. 



diminution in numbers, which, in view of the wholesale destruction, seems 

 hardly possible. 



The eggs are spherical and soft-shelled — that is, they are covered by a 

 thick skin, on which the limy covering is thin. The young are furnished 

 with a sharp point in front of the nostrils, like that on the beak of a young 

 bird, with which they tear their way out. At once, on freeing themselves 

 from the sand, they take to the water. I am told these animals are very 

 fond of the "Portuguese Men-of-War," Physalia; and that, when engaged 

 in eating them, they shut their eyes to avoid the stings, and may be taken 

 into a boat without pegging. Nets are also used in taking them. 



Rhizodonta. 

 Crocodiles have long bodies, long tails, short necks, and rather short 

 legs. The heads vary greatly in shape; in some the snout is long and 

 narrow; in other genera it is pointed, and in the alligators it is broad. 

 The condyle is single ; generally the vertebrae are concave in front. A com- 

 plete separation exists between the ventricles, but communication between 

 the atria mixes venous with the arterial blood going to the posterior portion 

 of the body. In the skin of the dorsal portions there are bony plates. The 

 epiderm is thin and corneous, closely attached to the skull, and arranged 

 over body and tail in transverse series of rectangular plates. The mouth 

 is large, and the jaws are strong. The teeth are numerous, conical in some, 

 compressed in others, and in all received in sockets by their bases. The 

 tongue is fleshy, short, non-extensile, and adherent to the floor of the mouth. 

 Nostrils, eyes, and ears are situated prominently on the top of the head, 

 which enables the animal to breathe, see, and hear without exposing itself. 

 The eye is provided with three lids; the pupil varies from horizontal to 

 vertical in the different genera. By means of valves the tympanic cavity 

 may be closed against the water. At the back of the tongue a valvular 

 arrangement closes the mouth cavity against the water when struggling 

 with the prey below the surface. In some respects the stomach resembles 

 that of birds; it is rounded and the coating is thick. The abdominal is 

 separated from the pectoral chamber by a muscular diaphragm. Croco- 

 diles are carnivorous; they commonly drown their prey, afterward going 

 to the shore to eat it. They are said sometimes to wait until it is partially 

 decomposed. Their flesh is rarely, if ever, eaten. Recently the skins have 

 come into use to a considerable extent for leather. The eggs are oblong, 



