MATTHEW, CLIMATE AND EVOLUTION 389 



were prevented from reaching the New World by the absence of any land 

 bridge or land approximation within their temperature limits. One: 

 genus of Zonuridse has likewise reached Madagascar. ; 



Bearing in mind the progressive limitation of northerly range of the 

 Lacertilia by the secular refrigeration of the polar regions during the' 

 Cenozoic, we can see that, if the distribution of land and water has not 

 greatly changed except within the 600 feet limit, any families arismg, 

 during the middle or later Tertiary would be limited to the old or to the; 

 new world. While the distribution of various lizards in oceanic islands 

 compels us to admit that they can cross considerable bodies of water and 

 obtain a foothold on an imperfectly populated island area, yet the proba- 

 bilities of their crossing the whole width of a broad ocean and maintain- 

 ing themselves against competitors trained in the broad arena of a great 

 continent appear to be very much less and almost negligible. Conversely 

 then, we may assume that a distribution, such as that of the Scincidse,. 

 Iguanidse, Geckonidse, Anguidge and Amphisbasnidffi, involves the evolu- 

 tion and cosmopolitan distribution of these families as early as the Eo-. 

 cene. The Agamidae, Varanid^, Lacertidse, Zonuridaj, Chamaeleontidse 

 are Old World families, and none are known from the New World. The 

 Zonuridee may well be regarded as of Ethiopian evolution; if not, they 

 must be a remnant of a very ancient stock. The same may be said of the 

 Chamseleons, except that if Ethiopian they reached as far as India. 

 The Lacertidse, the highest, or at least most t3rpical family of lizards, are 

 evidently the most recent development ; they have not yet reached Mada- 

 gascar or Australia, and their northern limit is higher than in any other 

 lizards. The Varanidas and Agamidse have not reached Madagascar but 

 have spread widely through Australia. The evidence from extinct lizards 

 is very slight, the remains are scanty and mostly too fragmentary for 

 positive family identification. Of the several genera from the Eocene 

 and Oligocene of North America, two are positively referable to the worm- 

 like Amphisbaenidffi, whose present distribution in tropical America, the 

 West Indies and Africa is thus partly explained as a remnant of a former 

 wider northerly range and presumably Holarctic. Of the remaining 

 North American Tertiary genera, Peltosaurus and Glyptosaurus are re- 

 ferred to the Anguidai;^^- the remaining genera are too fragmentary for 

 reference or have not been studied. ^^^ 



"2 Eael Douglass : Ann. Carn. Mus., vol. 4, p. 278. 1908. 



^*The recorded presence of Iguanidae (Iguanavus) in the Cretaceous and Eocene, while 

 not provable, is not unlikely; that of Chamwleon (C. pristinus) In tbe Upper Cretaceous 

 is improbable and based upon insufficient evidence; the reference of Thinosaurus (Middle 

 Eocene) to the Varanidte appears to be merely a matter of bibliographic convenience ; 

 the specimens are probably definitely referable, but the only expressed opinion as to 

 their affinities is by Boulenger (1891), who suggests their relationship to the Teiidse. 



