OUTLINES AND KEYS 169 



Legless lizards may be usually known from the 

 snakes by the tongue, which is not in their case 

 forked and threadlike, but flat and |)arely notched. 

 Where lizards have a threadlike forked tongue, limbs 

 are present. Eyelids and ear-drum membranes also 

 are usually apparent here and not in snakes. 



TOETOISE-FOEMS 



The following little outline will enable any one to 

 know the famihes of tortoise-forms. It is based on 

 shells and toes and is not just the natural order of 

 kinships, but is very apparent as a means of 

 describing : 



A. Shell soft, leathery outside. 



B. Back ridged ; limbs as flippers. Leather Sea Turtles. 

 BB. Back not ridged ; limbs as legs. Soft-shelled Turtles, 

 AA. SheU. hard, with horny scales outside. 



C. Limbs as flippers or paddles. Loggerhead Turtles. 

 .CC. Limbs as legs. 



D. Tail long, crested, or saw-toothed on top ; bottom 

 shell not a complete disk. Snapping Turtles. ■ 

 DD. Tail short, not crested ; bottom shell broad. 

 E. Toes free or with webs only between. 

 F. Twelve divisions in lower shell. 



Pond Turtles. 

 FP. Not twelve divisions in lower shell. 



Box-Tortoises. 

 EE. Toes not free ; all inside one mass of flesh ; 

 claws only showing. 



Land- Tortoises. 



The hinging of the shell can not be used in sepa- 

 rating families. There are " box-turtles " in both the 

 pond-turtle family and the box-turtle {Kinosternia) 



