266 LIZARDS AND CROCODILES AT THE ZOO 
crocodiles and their kin exhaust the list of noxious 
lizards at the Zoo, with one curious exception. The 
heloderin, a fat and torpid lizard from Arizona, is 
supposed to be the sole existing member of its tribe 
which possesses not only the poison-glands which 
exist in most of the toads, but also the true poison- 
teeth, with a channel for the emission of the venom. 
The lizard is about i^- ft. long, with a fat, fleshy 
body, a round tail ending in a blunt point, and a flat 
head with squared sides, resembling a small padlock. 
The whole body is covered with a curious coat of 
scales, like black and pink beads, arranged in an 
arabesque pattern. In its daily life it is a dull and 
stupid creature, feeding mainly on eggs, which it 
breaks and laps with its tongue. Its first and only 
victim was a guinea-pig, which was put into its cage 
with a view to testing the reports as to its poisonous 
nature, which were by no means universally credited. 
The lizard bit the guinea-pig in the leg, and the 
animal died in a minute and a half- — almost as soon 
as after the bite of a cobra. 
Eggs are favourite food with many lizards and 
snakes; but the “ monitor,” a very large and hand- 
some lizard approaching the size of the half-grown 
crocodile, is perhaps the most remarkable egg- 
swallower of the tribe. It bolts the eggs unbroken, 
and the oval morsel may be watched in its slow 
descent down the long neck until it disappears in 
the lower regions. Many of the smaller lizards in 
the house are almost unmatched for quaintness of 
