252 VERTEBRATE ZOOLOGY 



Basiliscus americanus (Fig. 138, F), the American basilisk, may 

 be chosen as an amphibious type. It is a large, conspicuous lizard 

 about a yard in length. It is characterized by a very pronounced 

 dorsal crest, which looks like a fin, a secondary sexual character 

 limited to the males. They lie on the branches of trees overhanging 

 the water and at the slightest danger drop off into the water and swim 

 rapidly ashore, using the fin only as a rudder. 



Amblyrhynchus cristatus (Fig. 139, E), the sea lizard, is as near an 

 approach to a true aquatic type as the Lacertilia afford. These rather 

 large, heavy-bodied lizards inhabit certain rocky shores on the Gal- 

 apagos Islands. They are great swimmers, using the flattened, finned 

 tail as a propeller. They habitually feed upon the seaweeds that 

 abound beyond the breakers, and they have to weather the waves 

 in order to secure their food. Often they prefer the really dangerous 

 breakers to their enemies on land, and seek shelter in the sea. 



Moloch horridus (Fig. 139, F) is one of the strangest of lizards. 

 Its integument is remarkable for its heavy spines. This animal has 

 been described as a lizard ant-eater and its peculiarities are considered 

 to be primarily adaptations for the ant-eating life. It certainly looks 

 to be well protected to withstand the attacks of ants. One peculiar 

 feature of the integument has attracted considerable attention; for 

 the skin is said to be hygroscopic, capable of absorbing moisture 

 from the air. This strange lizard rivals in bizarre appearance the most 

 fanciful monsters of long ago. Only its small size redeems it from 

 utter frightfulness of aspect. 



The only venomous lizard is the gila monster (Fig. 139, B), Helo- 

 derma horridum, a large, heavy-bodied lizard of the arid lands of our 

 southwest and Mexico. It has fang-like recurved teeth, which are so 

 grooved as to form ducts for the poisonous secretion of the labial 

 glands. The Gila is conspicuously marked with contrasting black 

 and orange patches and is often cited as an example of warning color- 

 ation, a common phenomenon among venomous reptiles. 



The largest living lizard is the monitor (Fig. 139, D), Varanus sal- 

 vator, a species that reaches a length of seven feet or more. Apart 

 from its great size the Monitor is a very generalized lizard, differing 

 very little from the primitive lizard-like reptile, Varanops, which 

 lived in Permian times. In Southern China and the Malaysian 

 region, where this lizard has its home, it is hunted by dogs and used 

 for food. 



