Scientific Intelligence — Zoology. 385 



too imperfectly known to enable any one to give a precise definition 

 of the different entomological regions, and to trace their respective 

 limits on the surface of the globe. In the absence of a natural division, 

 Latreillo proposed a systematic one, dividing each hemisphere into 

 zones, containing 12° of latitude, and subdividing each of these zones 

 by meridians distant 24°. We can now substitute for these arbitrary 

 limits those which result from the configuration of the ground, and 

 accomplish for the branch of natural history with which we are at 

 present concerned, what M. Milne Edwards has successfully done 

 in regard to the Crustacea. Proceeding as he has done, we find a 

 certain number of points, which may be considered, in regard to in- 

 sects, as centres of creation, whence the species have radiated, and 

 the mountains, in many cases, present us with the natural limits of 

 these regions, in the same manner as is done by the extent of seas in 

 the instance of the other articulata considered by M. Milne Edwards, 



We therefore divide the surface of the globe into 65 regions, each 

 characterized by the most typical genera and species which are pe- 

 culiar to it, and the limits of which are fixed at the point where 

 the greatest number of these genera and species cease to exist. 



The geographical distribution of animals, considered in relation to 

 their classification, may be of great importance in appreciating the 

 value of the characters on which generic groups are established. In- 

 deed, when we examine each family, and each genus by itself, we 

 are surprised to perceive that there are some of them which inhabit 

 certain countries of the globe of very limited extent, while others are 

 scattered over a much more considerable space ; and that others, 

 finally, inhabit the greater part, and sometimes almost the entire 

 surface of the globe. Moreover, we perceive that tribes and genera 

 exist sometimes comprehending a very great number of species which 

 have all the same peculiar /acie*, and the strongest resemblance to 

 each other in form and colours ; in such a case we are certain that 

 these are very natural genera> Coming after these, we find a consider- 

 able number of genera which are still with propriety regarded as natu- 

 ral, but which, at the same time, are so in an inferior degree to th« 

 preceding. All the species of which these are composed have a great 

 analogy to each other, but we may observe minute differences in form 

 and the greatest dissimilarity in colours. Lastly, when we pass to a 

 third sort, wo find genera, tribes, and entire families, which possess, 

 it is true, the common organs which furnish the most important 

 zoological characters, but which present very obvious modifications in 

 the form of the body, and particularly in the colours. We are soon, 

 however, enabled to ascertain that the differences between certain 



