2 BULLETIN 15 4, UNITED STATES NATIONAL MUSEUM 



slii]is of the coin])onent forms. It is hoped that this revision will 

 stiiuulate interest in the various lizards of the genus (Jjiemidophorus, 

 that it will show from what localities specimens are needed, and 

 that above all it will emphasize tlie lack of knowledge of habitat and 

 habits. 



The need for this work has been evident for a considerable length 

 of time. Cope (1900), after a lifetime of study, wrote that "the 

 discrimination of the North American species of this genus is the 

 most difficult problem in our herpetology." Prior to this a foreign 

 viewpoint was expressed by Giinther (1885), who elaborated his dis- 

 cussion of ChienildopJiorus sexUncatus by the following comment: 

 " Bocourt included in the synonymy of this species a number of 

 other names which have been created by American authors on very 

 slight grounds. I fully agree with him as to their value, but it is 

 difficult to determine to which species they should be referred. 

 From the character of the descriptions and figures I regard this 

 task as impossible."' 



The opinion of Gadow (lOOG) is well expressed by the following 

 extracts from his work on the IMexican species of Cnemidophorus : 

 " This Teiid genus is invaluable for the study of variation. It is 

 so plastic * * * that it is represented by some form in almost 

 every kind of terrain." * * * u ^[q^^ Qf n^^ ' species ' are so 

 variable that they may well drive the S3'stematist to despair. No 

 two authorities will, nor can, possibl}' agree on the number of ad- 

 missible species * * * (for) * * * almost every one of the 

 taxonomic characters investigated in this paper has an amplitude of 

 variation within some species which equals that of the wdiole genus." 



Much the same idea was expressed by Ditmars (1907) in prefac- 

 ing his treatment of the genus Cnemidophonis, thus — ■" In the prep- 

 aration of a resume of the species of Cnemidopliorous^ the writer 

 finds himself confronted by the most difficult proposition of any 

 3^et encountered in this work. Provided with a fine set of specimens, 

 he has attacked this obstacle from ever}^ side — and with very little 

 success * * * Nothing can straighten out this problem but the 

 work of some one who makes a specialty of the genus, gathers about 

 him elaborate series of all of the species and notes his observations 

 impartially." 



It is noteworthy that Camp (191G6), in reporting on a collection 

 from California, cited Cnemidophorus as a " remarkably unstable 

 genus," and that Schmidt (1922), in his consideration of the herpe- 

 lological fauna of Lower California, w^rotc that " An adequate under- 

 standing of the relations of the 15 species of Cnemidophorus in the 

 present list can only be reached by the comprehensive study of a 

 large series of each species." 



