TEIID LIZAKDS OF THE GEXUS CXEMIDOPHOEUS 251 



' iindoiibtedly ' C. sackil AViorrm.. Herp. ]\Iex.. \-6M. p. :iO. I have 

 been able to corroborate this, by the examination of the type specimen 

 in the Berlin Museum. This synojiymy does not apply to C. sexli- 

 neati(f< sacM'i Wiegm., as determined by Bocourt ior three specimens 

 collected by Salle at Oaxaca." 



Since GadoAv saw very few specimens of tesseUatus and did not 

 mention his criterion for making the identification, it is thought 

 best to question even his report until it is confirmed by a careful 

 re-examination of the type specimen. If the type is tesseUatus^ 

 sackil must be relegated to the synonymy of that form, but if it is 

 eitlier ferpJexus or gularis, it will liave priority, and one of these 

 will become a synonym of sael'H. 



GENERAL DISCUSSION OF RELATIONSHIPS 



It has been shown that the 25 species and subspecies of Cnemido- 

 phonis discussed in the preceding pages fall naturally into five 

 groups, as diagnosed on page 20. The origin and affinities of the 

 forms within each group have been considered in the respective sum- 

 maries and it is not the purpose of this discussion to repeat all of 

 this information here. Kather, it is intended to consider the rela- 

 tionship of the five groups of Cnemidophoriis to one another, or, in 

 other words, to trace their course of evolution, and to show the rela- 

 tionship of the genus Cnemidophmms to the other genei'a of the 

 family Teiidae. 



Before discussing the relationships of the various groups of 

 Cnemidophorus it seems best to consider the phylogenetic position of 

 the genus. As shown elsewhere (p. 11). CnemidopJiorus is very 

 closely allied to Ameiva. All of the positive evidence at hand seems 

 to indicate that Ameiva is ancestral to Cnemidophorus. The latter 

 genus differs from Ameiva chiefly in the loss of a lingual sheath and 

 in the universal posterior bifurcation of the scaly portion of the 

 tongue. Although the general evolutionar}' advance of Cnemido- 

 pJiorus over Ameiva is maintained and exhibited by many other 

 teiid genera, none of these could have been ancestral to Cnemldo- 

 ])honis on account of their universal possession of one or more 

 marked specializations, such as a strong transverse compression of 

 the teeth {Dierodon), the loss of digits (Teius, Bachia, etc.), the 

 possession of noticeably weakened or vestigial limbs and a general 

 serpentine form {Oj>hiognomon,Scolecosaiti\is^ etc.), the loss of eye- 

 lids {Gymnophthalmus. etc.). the loss of ear openings {Heterodac- 

 tylus, etc.). the separation of the prefrontals {Calliscincopus., etc.), 

 the complete loss of the prefrontals {Proctoporus^ Fholidoljohis^ 

 etc.) or of the frontonasal {Ophio(/nomon),erv\2LVge\\-iQXit of the dorsal 

 granules into regular series of polygons or scutes {Anadia, Euspon- 



