12 REPTILES OF THE WORLD 



Family Cinosternidce; the Musk and JSIud Turtles: 

 This is a small family of rather diminutive turtles, con- 

 fined to the New World. It is composed of two genera 

 ■ — Aromoclielys and Cinosternum; the former is repre- 

 sented bj^ three species, which, bj^ their aborted plastron, 

 large head and pugnacious disposition appear hke minia- 

 ture snapping turtles; they are usually called Musk 

 Turtles. Eleven species, called Mud Turtles, form the 

 genus Cinosternum; from the members of the former 

 genus they may be told at a glance by their wide 

 plastron. With both genera the structure of the plas- 

 tron is peculiar; the central portion or "bridge" is broad 

 and firmly united to the upper shell, while the front and 

 rear portions — the lobes — are hinged and movable ; these 

 lobes afford little or no protection to the species of 

 Aromoclielys, but with some of the species of Cinosterum 

 fold up tightly against the carapace in a fashion that 

 has caused the name of "box" turtles to be applied to 

 some of these reptiles. It should be understood, how- 

 ever, that the box turtles proper are the species of Cis- 

 tudo, belonging to the family Testudinidce, and the 

 structure of their plastron is altogether different; fhe 

 lower shell is divided by a central hinge and attached to 

 the carapace by elastic cartilage. 



The Musk and Mud Turtles are denizens of muddy 

 rivers and lakes. All are of dull colors. The general 

 hue of the upper shell is olive or brown, the shields 

 narrowly and obscurely margined with black. The 

 upper shell of all of the species is bluntly oval and 

 exhibits no traces of the flaring or serrated margin of 

 many turtles. To the novice the various species might 

 look very similar and be exceedinglj^ difficult to tell 

 apart. Among the Mud Turtles, the structure of the 

 plastron is the most important feature for identification. 



