376 M. Latreille on the Geographical Distribution of' Inserts. 
3. Many genera of insects, and particularly those which feed 
on vegetables, are spread over a great number of points in the 
principal divisions of the globe. 
4. Some others are exclusively proper to a certain extent of 
country, whether of the ancient or the new Continent. The fol- 
lowing genera are never found in the latter country ; Anthia , 
Graphypterus i Erodius , Pimelia , Scaurus , Cossyphus , Mylabris , 
Brachycerus , Nemoptera , Abeille ( Apis of Latf, Anthophora , 
as well as many others of the family Scarabeides , &c. ; on the 
other hand, the western hemisphere presents us with many ge- 
nera, which are not to be met with elsewhere, and of which the 
following are the principal : Agra , Galerita , Nilio, Tetraonyn\ 
Rutelia , Doryphora , Alurnus , Erotylus , Cupes , Corydahs , jL«- 
bidas, Pelecinus , Centris , Euglossa , Heliconivs , Erycina , 
jjw, &c. our bees are there replaced by the genera Milipona 
and Trigona. The genera Manticora , Graphiptera , Pneumora , 
Masaris , &c. have hitherto been found only in Africa ; the first 
and the third of these genera are even restricted to the Cape of 
Good Hope. The Colliuris is proper to the East Indies. The 
genera Lamprima , Helens , Paropsis , and Panops , come only 
from New Holland, and some neighbouring islands *. 
5. Many species, in their native country, affect exclusively 
certain localities, whether in low lying districts, or in those which 
are elevated to a fixed height. Certain alpine butterflies are 
always confined near the region of perpetual snow. When a 
traveller ascends among mountains to a height at which the tem- 
perature, the vegetation, the soil, are the same as those of a 
country much more northern, he there discovers many species 
which are characteristic of the boreal regions, and for which he 
would search in vain among the plains and valleys at the foot of 
these mountains. I have already cited some examples, which 
support this rule. If, in the same country, the temperature of 
certain low lying spots is modified by local circumstances, we 
there also find many species which occur more frequently a lit- 
tle further north, if the mean temperature has been lowered, or 
a little further south, if it has been raised. It is thus that we 
begin to observe to the north of the department of the Seine 
* The largest species of Cossvc, Zeuzcra and II~pad.es come from these countries. 
