OUTLINES AND KEYS 159 



Legless lizards may be usually known from the 

 snakes by the tongue, which is not in their case 

 forked and threadlike, but flat and barely 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. 



TORTOISE-FOKMS 



The following little outline will enable any one to 

 know the families of tortoise-forms. It is leased 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. 

 A A, Shell 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 Tuiiles. 

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

 E. Toes free or with webs only between. 

 F. Twelve divisions in lower shell. 



Pond Turtles. 

 FF. 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) 



