260 BULLETIX 15 4, UNITED STATES Is^ATIOXAL MUSEUM 



2. Pliocene: Further northward misratioii : probable evolution of the proto- 



.stock of the sexUncatus group in southern Mexico. 



3. Pleistocene : Continued northward migration ; evolution and differentiation 



of the tesscllatus and hypcnjihnits groups in the Lower Californian region. 



4. Recent: Further migration, evolution and differentiation in progress. 



Briefl}^, then, Gncmidophorus had its orip;in from Ameiva in 

 northern South America. This hind was its ancient or primary 

 center of dispersal until, with the passing of geological time and in 

 the course of extended northward migrations, a new or secondary 

 center was developed in Mexico. During the time of its spread 

 through Central America into Mexico and the United States, the 

 genus Cnemidophorus differentiated into five groups, of which the 

 most primitive, the lemniscahis group, is now chiefly South American 

 in range. The two most specialized, the hyperi/thrus and tessellatus 

 groups, have reached the extreme ranges for the genus in the north- 

 west. The deppii and sexlineatus groups are intermediate in range 

 and in characters between the northwestern hyperythnis and tessel- 

 latus groups and the southern letnniscatus group, except for the 

 northeastward extension of one form, sexlineatus. 



BIBLIOGRAPHY '' 



Adams, C. C. 



1902. Southeastern United States as a Center of Geographical Distribution 

 of Flora and Fauna. Biol. Bull , vol. 3, pp. 115-131. 

 Agassiz, L. 



1846ff. Index Universalis, Nomenclatoris Zoologici, pp. 1-393. 

 1846&. Rcptilia, in " Nomenclator Zoologicus," fasc. VI. pp. 1^8. 

 Ambrosetti. ,J. B. 



1SS7. Ob.servaciones sobre los Reptiles Fosiles Oligocenos de los Terrenos 

 Tercarios Antiquos del Parana. Bol. acad. nac. Cienc. Cordoba 

 (Argentina), vol. 10, pp 409-426. 

 Anders.son, Lars Gabriel. 



1900. Catalogue of Linnaean Type-specimens of Linnaeus's Reptilia in the 

 Royal Museum in Stockholm. Bihang till K. Svenska Vet.-Akad. 

 Hand!., vol. 26, sect. 4. no. 1. pp. 1-29. 



ANONYMOUS. 



1915. A Two Tailed Lizard (Cnemidophorus sexlineatus). Sci. Amer., no. 

 112, p 479. 

 Atkixson. D. a. 



1907. Notes on a Collection of Batrachians and Reptiles from Central 

 America. Ohio Nat., vol. 7, pp. 151-157. 

 Atsatt, Sarah Rogers. 



1913. The Reptiles of the San Jacinto Area of Southern California. Univ. 

 Calif. Publ. in Zool., vol. 12, pp. 31-50. 

 Babcock, Harold L 



1920. Some Reptile Records from New England. Copeia. No. 85. pp. 73-76. 



^■' The following list includes, in addition to tlie literature cited, the more importani 

 references given in the synonymy. However, readily accessible, modern titles which are 

 sufficiently cited in the synonymy have often been omitted. 



