Phylogenetic Systematics of I guanine Lizards 17 



to identify direct ancestors. Cladograms were constructed without the aid of computer 

 programs that minimize the number of instances in which shared characters appearing to be 

 synapomorphic on morphological grounds have to be interpreted as homoplastic in light of 

 other characters. In most cases, these cladograms were checked using the Wagner 

 programs in Farris's PHYSYS computer package installed on the California State 

 University CYBER system; however, in the analysis of relationships within Ctenosaura, 

 character incongruence was judged to be so low that such a check was unnecessary. In no 

 case did the computer analysis find a cladogram with fewer homoplasies than I was able to 

 find without it. 



