INSECTS IN GENERAL. 95 



them on the west to the preceding islands, and have possibly 

 received from them their productions. A similar communi- 

 cation, in consequence of the want of similar means, cannot 

 exist from the coast of America. Thus many of these islands 

 though American in their geographical position, may yet be 

 considered Asiatic, as to the animal and vegetable produc- 

 tions. 



The New Continent presents a similar progressive march, 

 in the changes of species relative to the notable differences of 

 latitude and longitude. M. Bosc found in Carolina many 

 species not to be found in Pennsylvania, and still less in the 

 province of New York. In Georgia, some species of lepi- 

 doptera are found, whose principal habitat is the West 

 Indies. The banks of the Missouri, about twenty degrees 

 west of Philadelphia, are the habitation of many peculiar 

 species. Other changes of this kind have been observed in 

 Louisiana. The entomology of the Antilles, with a few ex- 

 ceptions, forms an absolute contrast to that of the United 

 States. The isle of Trinity, in ten degrees of north latitude, 

 has some equatorial species, as for instance, butterflies of 

 those divisions named menalaus, teucer^ &c., which are not 

 to be seen in St. Domingo. In the former island are also 

 found quadrupeds unknown in the latter. There are species 

 in Brazil, which are likewise to be found in Cayenne ; but it 

 has also a multitude of others peculiar to itself. 



Nevertheless, in comparing the parallels of the Old and 

 New World, under the relation of temperature suitable to 

 the different species of insects, we shall find that these paral- 

 lels do not correspond in this respect. The southern insects 

 of the western hemisphere are not found so high as in ours. 

 With us, they commence to appear between 48° and 49** 

 N. L. ; there, they scarcely appear higher than 43**. When 

 we reflect on the physical constitution of America, and 

 consider that its soil is very much watered, considerably 



