1905.] 



AMPHIBIANS AND REPTILES. 



231 



the great plateau are I'atlier abrupt and in many parts are even 

 higher than the plateau itself, so that to gai]i the latter would 

 imply a descent. There are, as mentioned elsewhere, p. 240, 

 regions which offer a gradual, easy entry, and they have facilitated 

 the exchange of many species, but not of all, and of course not in 

 other districts. 



Species found in the hot country and on high mountains ; those 

 excluded from the plateau are marked * : — 



* Hylodes rhodojns, 



* Anolis nebidosus. 



* Zaimenis meoitovarms. 



* lihadinea vittata. 



* Leptophis mexicana. 



* ,, diplotrojns. 



* Leptodira albofiisca. 



* Xenodon rliahdocephcdus (?). 

 Geophis chalyhea. 

 Trhnorphodon tipsilon. 

 Elapsfidvius. 



III. Lastly there are some species which are'clifficult to group, 

 whether they have descended or ascended. For instance, most 

 kinds of Hylodes live rather high up ; they want pei'manent 

 moisture, and this H. rJiodopis gets on the high mountains and 

 in the hot forests of the Atlantic side ; only a very few returns 

 have been made from the truly temperate zone, and it is not known 

 from the plateau. 



Ryla eximia. 



* Bufo intermedius. 



* Hylodes palmatus. 

 Sceloporus variabilis. 



Sceloporus formosus. 



,, acanthinus. 



,, sjmiosus (?). 

 Coronella microp)holis . 



The list {infra, pp. 232-233) contains 70 species, of which 8 

 {-Diploglossus, Xenosatcrus, 1 Zamenis, 3 Leptophis, 1 Drymohvus, 

 and 1 Sceloporus) may be deducted as probably not ascending 

 beyond 6000 feet. The remaining 62 species, ovit of a pi-obable 

 total of 250 for Mexico from between the Isthmus of Tehuan tepee 

 and the line Mizantla to Mazatlan, represent about 25 per cent. 

 Of these, again, 30-32 (13 per cent.) seem to be restricted to levels 

 above 7000 feet. These have been marked with an asterisk (*). 

 If we add to them the following 10 species, which seem to be 

 restricted to the high plateau, 6000-8000 feet : — 



Sji&lerjies tnorio (also from 



" Jalapa"), 

 Scaphiojnts midtiplicatus, 

 Bufo GO')npactus, 

 Hyla mwtympanuin (?), 

 Phrynosoma orbiculai'e, 



Trop idonotus variabilis, 



, , scaliger, 



Homalocraniuin bocourti, 

 Crotalus viiliarius, 

 ,, salvini. 



we get a total of about 42 species, equalling 17 per cent., as 

 restricted to the cold and cool zones {cf. p. 228). 



