M. Latreille on the Geographical Distribution of Insects. 375 
which they make their abode are separated from each other by 
natural barriers, either entirely interrupting, or rendering very 
difficult the communication, such as seas, chains of highly ele- 
vated mountains, vast deserts, &c. Thus the Arachnides, the 
Insects, even the Reptiles of America and of New Holland, can- 
not be confounded with the animals of the same classes, which 
inhabit the ancient Continent. The insects of the United States, 
although often nearly allied to ours, are yet separated by cer- 
tain characters. Those of the kingdom of New Granada and 
of Peru, countries so near to Guiana, and equally equinoctial, 
differ nevertheless, in a great part, from those of the latter coun- 
try, their climates being divided by the Cordilleras. When one 
passes from Piedmont into France by the Col de Tende, a ma- 
nifest change may be observed. These rules suffer some ex- 
ceptions in regard to aquatic species. There are also certain 
insects of which the distribution is very widely extended. La 
Belle Dame , or Painted Lady Butterfly, (P. cardui ), so com- 
mon in our climate, and even in Sweden, occurs at the Cape of 
Good Hope, and New Holland presents a species almost entire- 
ly the same. The Sphinx du Nerion , and the Sphinx celerio or 
Silver- striped Hawk moth, have our own climate for thpir nor- 
thern limit, and for their southern the Isle of France. Amongst 
aquatic insects, the Dytiscus griseus , which lives in the waters 
of Provence and of Piedmont, is not unknown in Bengal. I 
do not speak from authors, who often confound the species of 
far distant countries, when they have some characters in com- 
mon, but from my own observations *. 
* Although the animals of the class Crustacea do not belong to my present 
subject, I may add the following general observations : 
1. The genera Lithodes , Corystes , Galathea , Homota , Phronyma , are proper to 
the seas of Europe. 
2. Those of Hepatus and Hippa have not yet been found, except in the Ame- 
rican Ocean. 
3. From the same, and the coasts of China and the Moluccas, comes the genus 
Limulus . 
4. The genera Borippe and Leucosia , inhabit particularly the Mediterranean 
and the seas of the East Indies. 
5. The last named seas give us exclusively the following genera : Orythia , Ma - 
tut a, Ranina , Albunea , and Thalassina. 
6. The other genera are common to all the seas ; but that of Ocypode is only 
found in warm countries. The great species of Grupsus come from South Ameri- 
ca and New Holland. 
