200 
ON THE GEOOKAPHICAL 
tirely similar, and often also absolutely identical with 
those of Malacca, of Bengal, of India, and even of Cey- 
lon. Sometimes, however, the species in those different 
places present differences more or less marked, and give 
rise to the establishment of local varieties. To judge 
from the small number of its productions known to us, 
the great Island of Madagascar would appear to have a 
Fauna of its own. Africa is not rich in Ophidians. The 
southern part of that vast peninsula produces species dif- 
ferent from those of Europe, or of other parts of the earth ; 
and those same species are often found dispersed over 
intertropical Africa, and even extending to the northern 
parts of that continent ; but besides a few peculiar species, 
those last countries produce several others, which inhabit, 
at the same time, almost all the countries bordering on the 
Mediterranean, even Syria, and consequently a great part of 
Europe. Most of the serpents of this last continent, finally, 
are spread over a great part of temperate Asia,— a region 
which appears to produce but a small number of peculiar 
species. 
The geographic distribution of genera or of families, 
viewed as representing the different principal forms, is not 
a less curious study, than that of the species. We see at 
once that the venomous snakes are distributed, perhaps, 
with the exception of some islands, in every country in- 
habited by snakes in general. These dangerous reptiles ap- 
pear not to dread cold, for they are found often as far to 
the north as the innocuous species. But their number is 
much more limited than that of the latter ; for if we 
reckon the number of all known Ophidians at 263, 57 of 
these are venomous,^ which makes the proportion of the 
venomous to the innocuous as 1 to 5. We shall see, 
however, afterwards, that this proportion is not the same 
in all countries of the globe, and that the number of 
venomous serpents, at least that of individuals, appears 
to be more considerable in naked and steril countries, 
^ We should also remark, that seven species of venomous snakes ex- 
clusively inhabit the ocean, where non-venomous serpents are never 
seen. 
