Mexican Amphibians and Reptiles. 703 
species only 2 (H. eximia and Manolepis) can be described as centred 
in the temperate belt, the remaining 3 having their centre in the 
cool, Rhadinea even well above the temperate zone. 
The Northern Genera and Species. 
(Total of species 52. Diagram No. III.) 
9 species reach, or extend above 12000’ altitude; of these are 5 Sonoran. 
11 R 10000 A Der 
29 or 30 species are found at 8000 R 
30 ; 7000 a 197053) 
al = 6000 n 197° 4 
32 i 5000 5 Ile 7: 
36 3 4000 he 20, 
33 R 3000 L la 
26 E 1000 = It? 
22 & Sealevel 1 14% 
*) Several species find here, or even above, their lower limit. 
Most of the species range through several levels and there- 
fore figure repeatedly in the diagram. One half of the Northerners 
occur at sealevel, more than °/, occur within or touch the Hotlands. 
9 species, 18°/,, are centred in the Hotlands, being now restricted 
to within the first 4000 feet; they have become Hotcountry species, 
or modified for, or by, the hot climate, against only 9°/, of Southerners 
which live completely outside the Hotlands, and against the single 
Southern form Rhadinea laureata, which lives apparently above 7000‘ 
elevation, and against 29°/, of Southerners which reach, or go beyond 
this level. 
13 Northern species, about 29°/,, have a range of 7000 feet or 
more, against only 5 Southerners. Or there are about 30%, of 
Northerners which occur within the cold zone and well within the 
Hotlands, compared with about 20°, of Southerners which occur 
between 3000 and 7000 feet; or only about 16°/, of Southerners 
which live well within the Hotlands and also above 7000 feet. 
Result. The Northern group contains proportio- 
nately twice as many species than the Southerners 
with so long a range as 9000 feet, and also twice as 
many species which have been modified for, or.by, the 
