222 DR. H. GADOW ON MEXICAN [June 6, 
two groups is the older. Not unlikely both are, in America, the 
divergent result of more generalised features; the one with the 
desert, the other with the typical forest as the leading motive, or 
rather the ultimate theme or goal for adaptation. We do not 
know the physical features of ancient Sonoraland. There need 
have been no deserts or semiarid tracts and rather barren plateaus. 
The ‘petrified forest” of Arizona; the fact that many of the 
present desert-like stretches from Northern Mexico, through New 
Mexico to Utah and beyond, are the basins of former lakes (many 
of them still rapidly receding); nay, even the prehistoric towns 
in the now inhospitable parts of Arizona and New Mexico—all 
these circumstances indicate that much of Old Sonoraland 1s still 
further tending towards the formation of deserts, just as clearly 
as enormous parts of Central Asia. 
Sonoraland had originally a much wider extent. It is obvious 
that the Tres Marias Islands were part of Tepic; there is also 
little doubt that the peninsula of Lower California was continued 
to the Revilla Gigedo Islands. That was at an epoch when the 
Gulf of California did not yet exist, the peninsula as such dating 
from the end of the Miocene. 
OPHIDIA. 
TyPHLopip£.—Only two species are known from Mexico. 
Typhlops tenwis from the State of Vera Cruz, ranging south to 
Guatemala; and Anomalepis mexicana from Nuevo Leon. The 
present centre of this family is South and Central America, 
whence they have extended into the Antilles (Puerto Rico). 
GLAUCcoNIID#.—Glauconia, the main genus, ranges from New 
Mexico, Texas, and Florida, far into South America, whence only 
the Lesser Antilles have been entered. Mexican localities are 
still very scattered. The northern species, e. g. G. humilis, ranges 
over the plateau and the Pacific slope; G. dulcis from New 
Mexico to Chilpancingo; while G. albifrons is a Central American, 
entering the Eastern and Western States of Mexico but avoiding 
the plateau. 
Borp#.—In Mexico only the Pythonine Loxocemus bicolor, 
recorded from Colima, Tehuantepec, and Guatemala; and the Boa 
imperator (incl. mexicana), ‘ Masacoatl,” which ranges from 
Eeuador through Central America into the Mexican Pacific and 
Atlantic Tierra Caliente, keeping strictly to the forest and bush 
lands. The Boine continue northwards as the arenicolous 
Lichanura of Lower California and of similar hot desert-like 
districts of Arizona; and the likewise arenicolous Charina, which 
extends from California to Washington. Another set of Boas, 
typical dwellers of luxurious tropical countries, occurs in the 
Antilles; all these, Hpicrates, Corallus, and Ungalia, have allied 
species in Central and South America. 
Consequently this archaic family is clearly divided into a 
