INTRODUCTION. 



23 



The volume containing the PoDURiE was written 

 by M. Gervais, who placed them after the Aphanivtera 

 (Pulex). He gives a carefiil resume of the works of 

 previous authors, and treats the modern genera as sub- 

 genera, retaining the term Podura for the group. He 

 adopts Bourlet's genus Heterotoma, and describes all 

 Nicolet's species as well as Bourlet's, so that many- 

 appear twice over. 



Nevertheless, in this work ^ M. Gervais has given us 

 an excellent summary of preceding memoirs on the 

 group, and has proposed some additional species, 

 which, however, are unfortunately described with much 

 brevity. 



The following is the list of species as given by 

 him : 



1 ' His. des Ins. Apteres,' v. iii. 



