1905. | AMPHIBIANS AND REPTILES. 229 
recorded from the hot-lands 70 or 69 per cent.! TI have left the 
two lists as they are, for fear that a revision would not be free 
from bias and might thus prove too much *. 
Fairly established is the fact that the Tierra Fria is inhabited 
by about 34 per cent., one third of the total number of species, of 
which one half, i.e. 17 per cent., are restricted to the cool and 
cold zone. 
Equally safe is the conclusion that in the Tierra Caliente occur 
69 or 70 per cent., about 50 of which (51 or 43) are restricted to it. 
This shows the richness of tropical life, especially if we consider 
the small extent of the hot-lands in Mexico in comparison with 
the rest of the country. 
Text-fig. 30. 
IAOOOEEE aaa teen, PNR) | TATE OA CE LIS VT LLY 2 eee 
([Xofote): TSS AS ae Se re Sere tg SSS So sas coos 
NOLO) RCs es tc a aot ee ty een ee el US ESE oY I asinine 2, 
TIERRA FRIA. 
BODO en nie aaa ee ee eS A ee 
TIERRA TEMPLADA. 
3000 ., — WWW co 2 REESE D a 
TIERRA CALIENTE. 
SEA LEVEL, Bitiw in Sti SEAS ZZ SSS SSS 
Diagram of the distribution of 250 Mexican species according to Altitude. 
~ Per cent. 
( Restricted to the Tierra Caliente ............ 44 
Southern or 
hot-country 1H) Ascending into temperate zone ................ 16 
species. | 
{ Wa Ascending into cool zone ............0...000. 5 
Species restricted to the temperate zone ... 6 
Restricted to cool and cold zone............... 17 
Northern or | 
cool-country ¢ Ht Descending into temperate zone............... 8 
species. | 
Descending into hot zone ............0000.. 4 
\ 
100 
Further, the whole fauna is practically composed of these two 
groups, whilst the species restricted to the temperate zone form a 
very small minority, 6 per cent., at the utmost 10 per cent. if we 
allow for the difficulty of classifying. 
This shows that the original stocks were either cool or tropical, 
* Probably all the numbers of species, as put down for the six groups, have been 
understated, but this would not much alter the proportions. or instance, on p. 228, 
the species given as occurring in cool to hot zones amount to about 24, but even 
half a dozen more might be added according to the interpretation of such 
records as “Amula” and ‘‘Omilteme,’” which may mean anything from 5000 to 
8000 feet. 
