INTRODUCTION. XI 
possessed much lower crests than the males. Specimens from the Ru Rima 
Rocks are smaller and darker than others from the main island. The 
stomachs contained nothing but insects. 
Heloderma, one of the largest North American lizards of the Sauria 
proper, inhabits the arid region extending from Utah to Tehuantepec. It 
is a clumsy, slow-motioned creature, and presents a repulsive appearance. 
The skin is covered with transverse series of thick plates, rounded and 
separated somewhat on the back, quadrangular and close together on the 
ventral surface. As if better protected from below, the Heloderma is said 
to turn himself on his back when attacked. The teeth are long, slender, 
sharp, and grooved. The saliva is very irritating when introduced into a 
wound, as is almost certain to be the case when the animal is enraged. 
It is generally considered to be fatal to the smaller animals. These are 
probably the only venomous of the Saurians. They are terrestrial and 
carnivorous; not at all particular as to kind and condition of food. Two 
species of the genus are all that are known. By some authors they have 
been placed in the Varanidw; for others they form the fainily Lelodermide, 
which disposition is to be preferred. 
The Varanide include the largest lizards of the old world. They are 
elongate and slender in build, and live near the water. The nostrils can he 
closed by valves, and are provided with air pouches, arrangements which 
greatly favor diving and remaining below the surface. 
True Chamaeleonide are not found in America. The home of the family 
is Africa and Madagascar. One or two species have found their way north- 
ward in Southern Asia and Europe. That wrongly called by the name in 
the Southern United States is an Anolis. Chamaeleons have compressed 
bodies, short necks, and prehensile tails. The head is angular, often crested 
or provided with one or more proboscis-like processes in front. The skin is 
covered with granular folds or scales. The tongue is long, slender, and very 
extensile; it has a club-shaped extremity, prehensile and viscous in front. 
The eyes are large, globular, very mobile, covered by a lid through the 
center of which there is a narrow opening. A Chamaeleon is able to watch 
an object ahead of him with one eye while closely examining with the other 
something that has attracted his attention in the opposite direction. The 
tympanum is covered by the skin, but as the latter is exceedingly sensitive 
to irritation of any kind, it is possible the hearing is not greatly interfered 
with. The limbs are slender, compressed, and each bears five toes disposed 
