INTRODUCTION. XI 



possessed much lowei' ci-ests than the males. Spccnncns from the Ru Rima 

 Rocks are smalUn- and darker than others from tlie main island. The 

 stomachs contained nothing but insects. 



Heloderma, one of the largest North ^Vmerican lizards of the Sanria 

 proper, inhabits the arid region e.xtending from Utah to Tehuantepec. It 

 is a clumsy, slow-motioned creature, and jiresents a repulsiA'c ap|)earance. 

 The skin is covered with transverse series of thick plates, rounded and 

 separated somewluxt on the back, quadrangular and close together on the 

 ventral surface. As if better protected fi'om below, the Heloderma is said 

 to turn himself on his back when attacked. The teeth are long, slender, 

 sharp, and grooved. The saliva is A^ery 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. Vty some authors they have 

 been placed in the Ynrnnidw: for others they form the fan)ily Ilc/odcniiidit', 

 which disposition is to be preferred. 



The Varaiii<J(v include the largest lizards of the old world. They are 

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

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

 greatly favor diving and remaining below the surface. 



True Chamaeleonidw 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. C'hamaeleons have cojnpressed 

 bodies, short necks, and prehensile tails. The head is angular, often crested 

 or provided with one ov more proboscis-like processes in front. The skin is 

 covered with granular folds or scales. The tongue is long, .slender, and xcry 

 extensile; it has a club-shaped extremity, prehensile and A'iscous in fi-oiit. 

 The eyes are large, globular, very m(d)ile, covered V)y a lid through tlu> 

 center of which there is a naiTOW opening. A Chamaeleon is able to watch 

 an object ahead of liim 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 



