56 M. Latreillc 07i the Geographical Distribution af Insects. 
&c. Now, if we divide by twelve degrees into twelve sections, 
and commence at the 84° of north latitude, a meridian which would 
proceed from the western parts of Spitzbergen or the neighbour- 
ing coasts of Greenland, we shall have a suite of latitudes^ 
which will correspond successively to those of the limits of coun- 
tries which we are to examine, under the general relations of 
Zoology and Botany. We shall continue these sections, each 
consisting of twelve degrees, beyond the Equator towards the 
Antarctic Pole, and shall stop at the 60°, under the parallel of 
Sandwich Land, which, on that side, may be regarded as the ne 
plus ultra of geographical discovery. 
These intervals may be divided by twelve^ the ahquot parts 
of their difference. Thus, for example, the arc comprised be- 
tween the 48° and the 36° of N. Lat., lessened necessarily by 
some of its parts, will give the numbers 45°, 42°, 39°, of latitudes 
to which many of my preceding observations apply. It appears 
to me always certain, that a space in latitude, measured by an 
arc of twelve degrees, some local variations being abstracted, 
produces a very sensible change in the mass of the species, and 
that such change is almost total, if the arc is doubled to 24°, 
as from the, north of Sweden to the^ north of Spain. This 
change takes place equally in the direction of the longitude, but 
in a ^luch slower manner, and at greater intervals, since the 
mean temperature, without particular and modifying causes, 
would be uniform under the same parallel. In proportion as 
one advances towards the poles, the extension of the species em- 
braces a greater number of geographical divisions, because that 
of the parallels of longitude diminishes progressively, on leaving 
the Equator. But other circumstances also tend to reduce their 
number. 
The insects of America, even those of its northern provinces, 
at least as far as Canada, differ specifically from ours, whilst 
those of Greenland appear to be European ; that last country 
shall be, for our geography of the insects of the Ancient Conti- 
nent, the point of departure of our first meridian. It would be, 
on every hypothesis, intermediate between the two hemispheres. 
The Canaries, the Cape de Verde Islands, and Madeira, are 
African, by the natur of their productions. Our meridian. 
