118 



AA. Carapace firm, ossified; dermal plates present; five claws on 

 front feet and four behind. 



B. Tail very long and strong, with a crest of tubercles; plastron 

 narrow and small, cross-shaped, with 9 plates (besides the bridge); 

 body highest in front: Family TI. Chelydridae. The Snapping Tur- 

 tles. ^ 



BB. Tail short, not crested; plastron broad. 



C. Lower jaw ending in a long sharp point; carapace highest be- 

 hind the middle, its edge not llariug outward; plastron with or 

 11 plates : Family III. Kinosternidse. The Box Turtles. 



CC. Lower jaw without long point at symphsis; carapace highest 

 at about the middle, its edge flaring outward; plastron with 12 der- 

 mal plates: Family IV. Emydida?. The Pond Turtles. 



In using the analytic key it must be remembered that this is pre- 

 pared for the purpose of enabling the student to trace his specimen 

 to its proper classification. It must belong in one of the two groups 

 in each respective portion of the key. For example, suppose a 

 person should find a specimen of turtle and wish to determine the 

 common and scientific names of the same. The carapace is not 

 leathery, and consequently does not belong to "A" and must belong 

 to "AA,'' or to those which have the carapace firm or ossified, and 

 dermal plates present. The tail is short and not crested, and 

 consequently belongs to the group ''BB" and not "B" of the above 

 key. The lower jaw is not pointed, the carapace or shell is highest 

 near the middle, and there are twelve plates forming the pastron or 

 shell on the lower side. This places it in the group "CC" and proves 

 it does not belong to "C." This has now traced it to the Family 

 name Emydidae, or Pond Turtles, to which family it belongs. To help 

 in determining each of the eighteen species of turtles found in this 

 State, we have prepared the above Analytic Key, which is applicable 

 to any, and includes all of these species, but not others. After 

 having traced the turtle to the correct family by the above Key the 

 student should turn to the page upon which the family is discussed 

 (page 139), and trace it to the correct genus and species in a similar 

 manner. 



