lieptiles and Aiiiphibiaus n/' Illinois. 249 



snake occurs in the centi-al part of the State, but grows more 

 coniDion southwards. The six-lined lizard appears to be very 

 local in its distribution in the State, and has only been ob- 

 served iu the central and northern parts. A.11 our species are 

 insectivorous. They are perfectly harmless to man, although 

 large examples of the blue-tailed lizard have received the name 

 "red-headed scorpion" under the impression that they are poi- 

 sonous. This cannot, however, be said of all lizards; a large 

 western species (Helodenna suspedum) introduces a poison 

 into wounds produced with its teeth, which may affect the sys- 

 tem very injuriously. Recent lizards are nearly all terrestrial 

 in habit, and none of the Illinois species are aquatic. 



SYNOPSIS OF THE FAMILIES REPRESENTED IN ILLINOIS. 



Tongue not bifid. Legs four. Scales imbricated, carinated 

 above. A fold of the skin on each side of the neck. Proxi- 

 mal end of clavicle simple Iguanid^. 



Tongue deeply bifid, with an ensheathing base. Legs wanting, 

 or with a pair of rudimentary hind legs. Body serpenti- 

 form. A lateral longitudinal groove. Proximal end of 

 clavicle simple Anguid.e. 



Tongue bifid, but with no ensheathing base. Legs four. Two 

 transverse subgular folds of the skin. Scales granular 

 above, large below. Premaxillary single. Clavical dilated 

 at proximal end Teid.e. 



Tongue notched at the tip. Legs four. No transverse subgu- 

 lar folds. Scales smooth and about uniform in size above 

 and below. Premaxillary double. Proximal end of clavi- 

 cle simple SciifciD^. 



Family IGUANID^. 



Tongue short, thick, fleshy, but slightly free in front, 

 scarcely bifid. Teeth attached to the inner face of the jaws, 

 pleurodent. Femoral pores present or absent. Premaxillary 

 single. Clavicle with simple proximal ends. Mesosternum an- 

 chor-shaped. A xiphisternal fontanel present. Abdominal ribs 

 generally wanting. 



