SPECIES OF HELODERMA 



appear to be two distinct kinds of heloderma, viz. 

 H. suspectum and H. horridum. One epithet is good, 

 the other bad. It is truly " horrid " in the applied 

 as well as in the literal sense of that adjective, for 

 the skin is roughened with warty scales underlain by 

 bony nodules. " Suspectum " is too dubious an ad- 

 jective ; for this lizard is not merely suspected but 

 known to be poisonous, being in fact the only lizard 

 which has this qualification. It was thought some 

 little time ago that the rare Lanthanonotus of Borneo 

 was also poisonous ; but recent study has proved that, 

 while related to Heloderma, it lacks the grooved teeth 

 of the latter. Experiments tried with Heloderma as 

 the main actor with the subsidiary parts played by 

 various frogs and guinea pigs has satisfied every one 

 that this lizard does bite with a poisoned effect ; more- 

 over the salivary glands, or rather some of them, are 

 furnished with several ducts which open in close apposi- 

 tion to the grooved teeth ; along the grooves run the 

 poison which is thus necessarily injected into the wound 

 made by the teeth. In fact, the gila monster poisons 

 precisely in the same fashion as the venomous colubrines, 

 those non-viperine snakes which are poisonous. On 

 the other hand, the courageous Dr. Shufeldt allowed 

 himself to be bitten by one of these lizards, but ex- 

 perienced no serious inconvenience " beyond the ordi- 

 nary symptoms that usually follow the bite of an 

 enraged animal." Like most lizards this animal is 

 lethargic and melancholy in appearance in captivity. 

 It seems indeed to have fewer and shorter repetitions of 

 those periods of briskness which even the most seden- 

 tary of lizards show at times. It can, however, be 

 roused, and then its wrath is terrible. Under these 

 circumstances, observes Dr. Shufeldt, " the animal 

 quickly rears its body from the ground by straightening 

 out its limbs, wheels about, opens its mouth widely, 



230 



