1906.] 



ON EVOLUTION IN MEXICAN LIZARDS. 



277 



3. A Contribution to the Study of Evolution based upon the 

 Mexican Species of Cnenudopliorm. By Hans Gadow, 

 F.R.S., F.Z.S. 



[Received March 2, 1906.] 

 (Plate XX. and Text-figures 61-83.) 



Contents. 

 General Part. 



Conclusions arrived at from the study of the differentiation, varial)ility, and 

 distribution of these Lizards, pp. 277-299. 



Systematic Paet. 

 Key to the main groups of Mexican and North-American CnemidopJ/ori, p. 300. 

 Description of the various kinds of CnemidopJiorus with special reference to their 

 variations, p. 300. 



Characters of South-American Cnemidophori, p. 301. 



C. sexlineatus, p. 302. 

 C. liyperythrua, p. 307. 

 Deppei-Geoup, p. 308. 



C deppei, p. 309, C deppei, var. 



coziimela, p. 316. 

 C guttatus guttatus and G. g. 

 iinmutahilis, p. 320. 

 Gulaeis-Geoup, p. 327. 



Tabulation of characters of the 



^M/flr*s-Group, p. 329. 

 Key to the species &c., p. 328. 

 C. mariarum, p. 328. 

 C. gularis, p. 330. 

 C. semifasciatus, p. 334. 

 C septemvittatus , p. 335. 

 C scalaris, p. 335. 

 C. communis, p. 337. Tabulation 

 of characters, pp. 340, 348. 



C. communis occidentalis, p. 339. 

 C, communis copei, p. 346. 

 C communis australis, p. 352. 

 C. communis hocourti, p. 356. 

 C. we.v/crtMHs, p. 358. Tabulation 



of characters, p. 362. 

 C. mexicanus, var. balsas, p. 363. 

 Tessellatds-Geoup, p. 367. 

 Key to the species &c., p. 368. 

 C. pevplexus, p. 368. 

 C. tessellatus, p. 369. 

 C. maximus, p. 371. 

 G. ruhidus, p. 371. 

 C. melanostetlius, p. 372. 

 G. mc(rti/ris, p. 373. 

 G. octolineatus, p. 373. 

 G. inornatus, p. 373. 

 C. labial is, p. 374. 



Reterences to the original descriptions of species, pp. 374-375. 

 Map : Plate XX. 



It was in the forest and bush region of the Atlantic Tierra 

 caliente, on the confines of the States of Oaxaca and Vera Cruz, 

 that I first became personally acquainted with Cnemidophorus. 

 There was only the spotted, large C. guttatibs, but further east, 

 whei-e the Savannah begins, its place was taken by the small, 

 striped C. deppei. 



On the Pacific side of the Isthmus, at Tehuantepec and Salina 

 Cruz, was C. deppei and the large, conspicuously striped G. im- 

 mutahilis. These kept on further inland until near the foot of 

 the abrupt southern edge of the plateau. The small C. deppei 

 ceased, and a very large, tiger-barred lizard, C. mexicanus, made 

 its appearance. The striped G. immutabilis seemed to continue, 

 but on closer examination it was found that all the striped mid- 

 sized to large specimens were the young and immature of G. mexi- 

 canus, which reigned supreme on the open southern plateau until 



19* 



