A STUIlY OF THE TEIID LIZARDS OF THE GEXUS 

 CNEMIDOPHOIJI'S. Wri'H SPECIAL KEFE15ENCE 

 TO THEIR PHYLO(iENETIC RELATIONSHIPS 



By Charles E. Burt 

 Of Trinitii Uiiivcrsitij, Waxahachie, Texas 



INTRODUCTION 



The genus Cnemklophorus, one of the largest and most important 

 units within the famih' Teiidae, is a complex assemblage of species, 

 subspecies and phases, which reaches its maximum diversity in 

 North America. The forms here assigned to this genus occur from 

 southern Brazil to the northern United States, both on the main- 

 land and on the closer neighboring islands, thus comprising one of 

 the most widespread and diaracteristic groups of lizards of the 

 New World. 



Within the remaikably narrow generic limits of C nemldophorus, 

 an amazing amount of variation is seen. Its unusually extensive 

 distribution brings it into contact with a great variety of habitat 

 conditions to which its forms seem to be constantly adapting them- 

 selves through their apparently natural tendency to vary. INIore- 

 over, in many of the species each individual shows an intricate 

 series of pattern stages during development, and abnormalities are 

 frequentW found in the various populations. ]\Iany of the sup- 

 posed species have been described from only a few specimens, often 

 wholly without regard to the geographical probabilities, and fre- 

 quently without reasonable allowances for the normal develop- 

 mental and environmental pattern variation. Furthermore, the 

 genus itself has never been clearly defined and it is found that 

 some of its oldest species should have been referred to the very 

 closely related genus AmeliKi. In the absence of a comprehensive 

 review of the genus Cnemidoplioru's, it is not surprising that there 

 has always been much uncertainty as to the number of forms, their 

 relationships, distribution, and ditlerentiation, one from another. 



The present study has been undertaken to bring order into this 

 perplexing group of lizards, and to discover the origin and relation- 



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