290 VERTEBRATES I REPTILES. 



shelled eggs, with a glazed surface. Three genera and 

 about half a dozen species are found in North America. 



The Genus Aromochelys, Ozotheca, Ag., contains the 

 Musk Tortoise, A. odoratum, Gr., O. odorata, Ag., of the 

 United States, which has the shell three and a half inches 

 long, and emits a strong odor of musk. 



The Genus Thyrosternum contains the Mud Tortoise, 

 T.pennsylvanicum, Ag., Cinosternum penn. of authors, from 

 Pennsylvania southward and westward, which is three and 

 a half inches long, and emits a slight odor of musk. 



CHELYDROID^E, OR SNAPPING-TURTLE FAMILY. This 

 Family comprises turtles which have the body high in 

 front, low behind, head large, neck large and long, both 

 Fig. 154- jaws strongly- 



hooked, the tail 

 long and pow- 

 erful, and the 

 sternum small. 

 They are a- 

 quatic, but are 



Snapping Turtle, C. serpentina, Schw. Very frCQUent- 



ly found upon the land near the water. They are exceed- 

 ingly powerful and voracious, devouring smaller reptiles, 

 fishes, young ducks, and other animals. When molested, 

 they take the defensive, raise themselves upon their legs 

 and tail, open wide the mouth, and, forcibly throwing the 

 body forward, snap the jaws upon the assailant with fear- 

 ful power. They are fully a match for anything which 

 they are likely to meet with except man. The eggs are 

 numerous and spherical. Three genera are known, each 

 with a single species, and two of these are American. 

 The Genus Macroclemys, Gypochelys, Ag., contains the 

 Alligator Turtle, M. lacertina, Ag., of the Southern States, 

 which sometimes attains the weight of two hundred 

 pounds. It seizes fish, and, holding them down with its 

 feet, devours them somewhat as a hawk devours its prey. 



