118 Dr. H. Gadow. Evolution of the Colour-pattern [May 22, 



The under parts of neck, throat, and arms are greenish-white, 

 yellowish on the tail ; chest and abdomen are dark blue, mottled with 

 white. Sometimes, not only in old males, faint blackish mottlings 

 extend upon the collar, and even upon the throat. 



Such spotted C. bocmrti have hitherto been found in only a few, 

 rather isolated districts. I myself found them in the immediate vicinity 

 of the town of Oaxaca, amongst the tangled growth of shady trees and 

 hedges. A large gravid female in the National Collection, from Santo 

 Domingo de Guzman on the isthmus, and several immature specimens 

 from the Sierra de Nayarit, Jalisco (oak forests) are intermediate in 

 colour between C. bocourti and C. nuxicanus. Others are known from 

 " California." 



Ameiva undulata, Wiegm. (fig. 6, PI. 5). 



The only species of this otherwise South and Central American 

 genus, which extends into Mexico, where it is an inhabitant of the hot 

 and moist tropical open forest belt, frequenting open and sandy 

 patches. 



Very young specimens, about 45 mm. in length, are very dark 

 brown, with two pairs of yellow lines extending from head to tail. In 

 older specimens much black pigment is deposited on either side of 

 stripe 1, which thereby is encroached upon and broken up into streaks 

 and spots. The whole field between stripes 1 and 2 becomes mottled, 

 or vermiculated with brown and black, the black disposing itself in 

 irregular, incomplete cross-bars. Some females remain in this 

 condition. 



A further stage is entered upon by the appearance of one or more 

 rows of patches in the field 1 2, at first pale brown, then gray, 

 ultimately, white; small whitish spots and dots appear between 

 stripe 1 and the central scales. This is typical of many adult females 

 and immature males. In the final stage, characteristic of most adult 

 males, the patches on the field 1 2 become confluent into a broad, 

 irregularly bordered, very conspicuous white band, extending from the 

 tail to the shoulder. The lateral spots are enlarged and combined 

 transversely into pure white patches. Stripe 2 is completely over- 

 whelmed by blackish pigment, only a narrow and faint streak remain- 

 ing on the neck. 



Some adult females remain at intermediate stages, the lateral spots 

 and those of the original line 1 remaining small, while the newly- 

 formed light row in the field 12 is represented by a pale gray band, 

 bordered by black ; the whole of stripe 2 remains as a faint, narrow, 

 streak. 



