LIZARDS. 317 



rope (Dalmatia, Hungary, Eussia) and West-Central Asia.* In the 

 region lying south of the San Francisco-Galveston line, which is 

 largely in the form of parched or desert tracts, the prevalence of a 

 considerable number of tropical or South American types imparts a 

 distinct individuality, or non-North American character, to the 

 fauna, which is best expressed in the family of iguanas (Iguanidss). 

 This group is represented by not less than forty species, the greater 

 number of which belong to the genera Sceloporus and Phrynosoma 

 ("horned-toad"), one species of the latter genus penetrating as far 

 north as Dakota, f Inhabiting the same tracts, but extending its 

 range to Tehuantepec, is the venomous Heloderma. A single spe- 

 cies of amphisbsenian, the ' ' thunder- worm " (Rhineura Floridana), 

 is known from Florida. The so-called chamseleon of the Southern 

 United States is the green goitred lizard Anolis. 



The more distinctive or most largely represented tropical fami- 

 lies of lizards are the iguanas, agamas, monitors, geckos, amphis- 

 baenians, and chamKleons. The first of these is almost exclusively 

 American, and is represented by probably not less than three hun- 

 dred species, of which nearly, or fully, one-third belong to the 

 genus Anolis, whose members especially abound in the West India 

 islands. The genus Iguana is more properly South American, al- 

 though also found in some of the West Indies, and penetrating 

 northward into Mexico. Basiliscus, the basilisk, likewise ranges 

 into Mexico. In addition to the forms that have already been in- 

 dicated as belonging to the United States, may be mentioned Uta, 

 Callisaurus, and Holbrookia, the last of which is sufficiently abun- 

 dant in certain parts of Texas and the transition-region to the 

 northwest. The most remarkable member of the family is the 

 Galapagos leguan .(Amblyrhynchus), which is partially marine in 

 its habits. Brachylophus inhabits the Feejee Islands. No iguanian 



* A variety of this species also occurs in Morocco. M. Boulenger has re- 

 cently attempted to show ("Ann. and Mag. Nat. Hist.," Aug., 1885) that 

 the North and South American lacertilian faunas are, strictly speaking, one, 

 the Neogean, a conclusion which is not borne out hy the facts of distribu- 

 tion. The misconception arises from the incorporation of the tract lying 

 south of the line indicated above with the North American faunal region 

 proper, while in reality it is a transition-tract more nearly Neotropical in 

 character than '^ Nearctic." 



+ Phrynosoma orbieulare was found by Mr. Geddes on the plateau of 

 Mexico at an altitude of 7,500 feet. 



