504 ZOOLOGY. 



ten day?, the skin finally separating from tlie spines of tne 

 head and the claws. (Hoffman.) 



Our most common lizard in the Middle and Souttiem 

 Scares is Scehjaorus undulatus Harlan (Fig. 440). It is 

 «ommon, running np trees. The iguanas are very large liz- 

 ards inhabiting the ^est Indies and Central America : the 

 headisprotectedbynumerous small shields, with a dorsal row 

 of bristling spines. They are about three feet long, Htb in 

 the lower branches of trees, and are said to be excellent eat- 

 ing. A still larger form, closely resembling the iguanas, is 

 the sea-lizard {Amlhjrhynchus) of the Gralapagos Islands, 

 where it lives in the rocks by the shore, feeding on seaweeds. 

 These large creatures are among the largest of existing liz- 



Flj. 443.— Toujaeof Chameleon. 2^atnial sizie— After Rymer Jonea. 



ar'l;. being eighty-fire centimetres (over 3 feet) in length. 

 C 1 >sely allied to the iguanas were a number of extinct sau- 

 riaiis of colossal size which flourished in the Jura-Trias and 

 Chalk Periods. 



The largest lizard in Mexico is the Heloderma horridum 

 -of Wiegmann. It grows to the leiigth of one metre (over 

 three feet). It is allied to the iguanas, but the body is 

 heavily tnberculated. HeloJenna susjyectum Cope, inhab- 

 its southern Utah, Arizona, and Xew Mexico. The laro-est 

 of the esi-ting lizards are the monitors, or species of Vara- 

 juis. of tropical rivers, which nearly rival the crocodUes in 

 size, being five or six feet in length. 



Order 4. Chelonia. — Although the tortoises and turtles 

 are a weU circum-eribed group, «ith no aberrant or connect- 



