^6 REPTILES AND BATRACHIANS 



The two representatives of the family Helodermatid^, 

 which is composed of a single genus, Heloderma^ are the 

 only poisonous lizards, their teeth being grooved, and those 

 of the lower jaw connected with a large poison gland; 

 they inhabit Mexico and Arizona. The head is very large, 

 depressed and, like the elongate body, covered with bony 

 tubercles. The limbs, which are provided with long 

 claws, are, although short, strongly developed. The 

 protusible tongue is thick, fleshy, and bifid at the tip. 

 The tail measures about half the length of the head and 

 body, and is much swollen, especially in H. suspectum. 



The Gila Monster, H. suspectum, grows to a length of 

 two feet. Its general colour is salmon-pink, reticulated 

 with purplish brown or black, some of the tubercles 

 resembling coloured beads. 



The numerous experiments that have been made with 

 this lizard on small animals, and the several cases of death 

 in man, which have occurred in Arizona, demonstrate 

 beyond all possible doubt the virulence of its poison. 

 Mme. Phisalix, who has conducted experiments on the 

 reciprocal action of the poison of this species and that 

 of our Common Viper, has shown that neither enjoys 

 immunity, and that the latter, injected with Heloderm 

 poison, is stupefied after a few seconds, dying within 

 twenty-four hours, while, when the Viper is made to bite 

 the tail of the Heloderm, the lizard will die about fifty 

 hours later. This lady was herself bitten by the animal 

 while handling it for her experiments, and, in spite of the 

 fact that only a few of the reptile's teeth penetrated the 

 flesh, was laid up in consequence for a period of nearly three 

 months. We can therefore imagine the results that are 



