PREFACE. 



The animals which form the subject of this work 

 were first grouped together by Latreille under the 

 name of Thysanitea : to me, on the contrary, they 

 appear to form two distinct orders, for one of which I 

 have proposed the term Collembola. They have 

 hitherto been much neglected by English naturalists. 

 And they from their small size, and the dehcacy of their 

 structure, which renders them uninteresting to col- 

 lectors, together with the absence of well-marked meta- 

 morphoses, this is, perhaps, not surprising ; yet the 

 two groups are in many respects of singular interest. 



It is unfortunate that the two naturalists, M. 

 Nicolet and M. I'Abbe Bourlet, who have of late years 

 contributed most to our knowledge of the Collembola, 

 should have published the results of their labours 

 almost simultaneously; and as they worked quite 

 independently of one another, the consequence has 

 been to complicate greatly those difficulties of nomen- 

 clature which, owing to the brevity of early descrip- 

 tions, were already sufficiently embarrassing. 



Several, for instance, of Linnaeus' specific characters 

 would apply to more than one species, and even to 

 more than one genus. I have reason, therefore, to be 



