342 IN8ECTA. 



the three finer seasons of the year produces species peculiar to it. The 

 females and males of those which live in societies, however, enjoy a 

 longer term of life. Individuals hatched in autumn shelter them- 

 selves from the rigours of winter, and reappear in spring. 



The species, like those of plants, are circumscribed within geogra- 

 phical limits. Those of the western continent for instance, a very 

 few, and all from the north, excepted, are strictly peculiar to it ; such 

 also is the case with several genera. The eastern continent, in turn, 

 possesses others which are unknown in the western. The Insects of 

 the south of Europe and north of Africa, and of the western and 

 southern countries of Asia, have a strong mutual resemblance. The 

 same may be said of those which inhabit the Moluccas, and more 

 eastern islands, those of the Southern Ocean included. Several 

 northern species are found in the mountains of southern countries. 

 Those of Africa differ greatly from the opposite portions of America. 

 The Insects of Southern Asia, from the Indies on the Sind eastward, 

 to the confines of China, are very much alike. The intertropical 

 regions, covered with immense and well-watered forests, are the 

 richest in Insects of any on the globe; Brazil and Guiana are 

 particularly so. 



All general systems or methods relative to Insects are reduced 

 essentially to three. Swammerdam based his on their metamor- 

 phoses ; that of Linnaeus was founded on the presence or absence of 

 wings, their number, consistence, superposition, the nature of their 

 surface, and on the deficiency or presence of a sting. Fabricius had 

 recourse to the parts of the mouth alone. In all these arrangements 

 the Crustacea and Arachnides are placed among the Insects, and in 

 that of Linnaeus, the one generally adopted, they are even the last. 

 Brisson, however, had separated them, and his class of the Crustacea, 

 which he places before that of Insects, comprises all of those animals 

 which have more than six feet, or the Insectes Apiropodes of M. 

 Savigny. Although this order is more natural than that of Linnaeus, 

 it was not followed ; and it is only in modern times, that anatomical 

 observations and their rigorously exact application have brought us 

 to the natural method *. 



I divide this class into twelve orders: the three first of which, 

 composed of apterous Insects, undergoing no essential change of 

 form or habits, merely subject to simple changes of tegument, or to a 



* Cuv., Tabl. Elm. de 1'Hist. Nat. des Anim., and Logons d'Anat. Compar. ; 

 Lamarck, Syst. des Anim. sans Vert&b. ; Latr., Precis des Caract. GLnr. des Insect., 

 and Gen. Crust, et Insect. For more minute details, see also the excellent elemen- 

 tary work of Kirby and Spence. 



