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 Telmantepee. 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 Varanidce; for others they form the family Helodermidce, 

 which disposition is to be preferred. 



The Varanidce include the largest lizards of the old world. They are 

 elongate and slender in build, and live near the water. The nostrils can lie 

 closed by valves, and are provided with air pouches, arrangements which 

 greatly favor diving and remaining below the surface. 



True Chamaeleonidce 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 



