654 



COMPARATIVE ANATOMY 



There are three 

 orders (Fig. 381). 



sub- 



Crocodttus (intcricanus (crocodile) 



Fig. 380. 

 Crocodjlia. (After Basket! and Ditmars.) 



Sub-Order I. Geckones. 



These are the primitive 

 types having amphicoelous 

 vertebrae (Fig. 404), and no 

 bony temporal arches. They 

 have dilated clavicles, sepa- 

 rate parietals, eyes with 

 movable lids, broad, fleshy, 

 protrusible tongue, which is 

 nicked at the end. Usually 

 harmless. The tail is loosely 

 articulated and comes off 

 when seized although a new 

 one grows quite readily 



Sub-Order II. Lacertae. 



Most modern lizards be- 

 long to this group. Their 

 vertebrae are precocious and 

 solid. The ventral portions 

 of the clavicle are not 

 dilated. 



There are cursorial types, arboreal types, volant types, an aquatic 

 type, a fossorial type and an ant-eating type, so-called from their vary- 

 ing modes of life. 



The Gila Monster (Heloderma horridum) of our Southwestern 

 States is the only poisonous lizard known, while the monitor (Varanus 

 salvator) grows to the greatest length, something like seven feet or more. 



Sub-Order III. Chamaeleontes (Chameleons). (Fig. 382). 



These animals are the ones so well known on account of their 

 ability to change color, and the enormously long tongue by which they 

 readily catch insects at a distance of some seven inches. 



Chameleons are highly specialized, the body is laterally compressed, 

 the tail is prehensile, and the toes are parted in the middle so as to be 

 used for grasping. They are found mostly in Madagascar. One species 

 is found in Southern Europe. 



Division II. Ophidia (Snakes). 



Snakes are really Sauria or Squamata in which the right and left 

 halves of the lower jaw are connected with an elastic ligament, thus per- 

 mitting the mouth to stretch greatly. They are usually limbless or have 



