1905. ] AMPHIBIANS AND REPTILES. 221 
LIguanide: : 
1, Xerophile, humivagous; Sonoran, non-Antillean. 
2, Arboreal; Central and South American and Antillean. 
Tejide.—Neotropical, with Ameiva into Tierra Caliente and 
Antilles, Cnemidophorus far into United States. 
Anguide.—Mexican, Central American and Antillean, reaching 
far North and South. ; 
AXenosauride. 
Helodermatide. 
Scincide : 
1. Northern America and plateau of Mexico, non-Antillean. 
2, Central American into Mexico and Antilles. 
Aantustide : 
1. Sonoran, non-Antillean, 
2. Central American and Antillean. 
Amphisbenide.—Mexico, Central America, and Antilles; 
formerly much farther north in the United States ; extending 
far into South America, 
} Mexican, non-Antillean. 
These statements are intended, in their reduced form, to 
indicate the probable centres of dispersal of the various families. 
It is important that of these 10 families no less than 7 have 
representatives in the Greater Antilles, and that these Insular 
members belong, in not a few cases, to Insular, peculiar genera, 
e.g. Cyclura and Metopoceros of the Iguanide, Celestus of the 
Anguide, Cricosauras, Cricolepis of the Xantusiide ; and it is also 
worth noting that Amphisbena itself occurs in Puerto Rico, on 
the Virginia Islands, and South and Central America, but not in 
Mexico, Xenosawrus and Heloderma, each the sole member of a 
family, are restricted to Mexico in a slightly wider sense. Most 
of the Anguide and Iguanide, and all the Xantusiide, are centred 
in tropical and semitropical America. We may fairly conclude 
that at least the Amphisbeenide, Anguide, Iguanide, Xantusiidee, 
are very old inhabitants of the ancient Sonoran-Central American, 
and Antillean mass of land, Of these families the Amphisbenide 
may well be autochthonous. The Tejide alone are unmistakable 
Southern immigrants from an original centre, probably Brazilian, 
not N.W. South America; otherwise it would not be obvious wh 
only so few Tejide have extended beyond the present South- 
American continent. They (Anolis and Ameiva) were the latest 
immigrants into the Central Land Complex just before the 
Antillean separation, after which these genera and Cnemidophorus 
could continue their continental progress northwards. 
It is suggestive that so many of these families fall into a north- 
western, typically Sonoran and Pacific, xerophile, and a southern, 
more Atlantic group with predominant hygrophile characters ; 
the Antillean forms naturally siding with the latter. The 
Mexican plateau, instead of connecting, rather severs these two, 
mainly ecological groups, the connection passing round to the south 
of the plateau. It must remain a moot question which of the 
