Bejitilia and BatracJiia of Wisconsin. 157 



CiSTUDO, Fleming. 



C. clausa, Gmelin. Commou Box Turtle. 



Varies greatly in color; back ground always dark (black, brownish or 

 drab) with yellowish spots or blotches; shell nearly oblong in outline; 

 plastron sometimes truncate; anterior lobe the shorter, generally found in 

 high but moist woods. Very rare. Two siDecimens have been reported 

 from Walworth county.^ Length of carapace about six inches; height 

 about three inches. 



C. ornata, Agassiz. Northern Box Turtle. 



In many respects very similar to the last. Shell nearly orbicular and 

 without keel. " Grant county; rare." Hoy: Walworth county. 



FAMILY CHELYDRID.E, SNAPPING TURTLES. 



Aquatic species of great strength, living in ponds and muddy streams. 

 Represented by two genera and two species. 



KEY TO THE GENERA OF CHELYDRID^. 



a. Head covered with skin; tail with two rows of scales underneath Chelydra. 



b. Head covered with plates; tail provided with many scales underneath in 



several rows Macrochelys . 



Chelydra, Schweigger. 



C. serpentina, L. Common Snapping Turtle. 

 Very common and well known. 



Macrochelys, Gray. 



M. lacertina, Schw. Mississippi or Loggerhead Snapper. 



This ferocious turtle is occasionally found in the Mississippi river as far 

 north as the mouth of the Wisconsin. Hoy. 



FAMILY EMYDID.-E, POND TURTLE. 



The members of this family are generally very mild when approached, 

 simply relying on the rapidity of their motions or by plunging into the 

 water to effect their escape. Some forms (Cri/semys), however, when taken 

 in the hand, wUl snap quite savagely at the fingers. 



Represented by five genera and six species. 



KEY TO THE GENERA OP EMYDID^. 



a. Crapace more or less depressed or flattened ; toes webbed; plastron broad 

 and flattened, yellowish: 



(a). Plastron movable on the carapace and divided, the anterior division being 

 smaller and movable by a transverse lilnge; plastron with irregular 

 black spots Einys. 



(b). "Upper jaw notched in front; shell not keeled in adult" (Jordan); toes 

 strongly webbed; plastron iniaiovable; carapace witli outer plates usu- 

 (lUy marked with red Chri/semy.i. 



1 Since writing the above, the author has idantifled specimens of C. clauna from Milwau- 

 kee, Pine Lake, La Crosse and Green Bay. 



