TEIID LIZARDS OF THE GEXUS CNEMIDOPHOltUS 



259 



An outline of the apparent evolution of CneniklophorUf^ (aceoni- 

 plisliecl through a series of phylogenetic changes by no means clear 

 at all points), with reference to geological time, is given lielow. Tin) 



FioiRE 38. — Map showing distribution of the five groups of the genus Cnemi- 



DOPHORUS. XoTE the DISTINCTIVE RANGE OCCUPIED BY EACH 



geological data u}K)n wliich these conclusions are essentially based 

 were summarized by Schuchert (1929). 



la. Early Mioceue: Cneniidophonts not differentiated from Amciva. 



b. Middle Miocene: Development of tlie protostock of tlie Icnuiiscatus group 



and its spread over northern South America. 



c. Late Miocene: Northward misration ; evolution of tlie protostock of the 



dcppii group in Central America. 



