10 INTRODUCTION. 



sible to fix satisfactorily, as tlie descriptions given by 

 Linnaeus are quite insufficient for the purpose. 



De Geer, ' Gescli. Ins.,' vol. vii. 



Podura arborea nigra := Isotoma arborea. 



„ „ grisea Degeeria annulata. 



„ aquatica nigra Podura aquatica. 



„ ,, grisea Isotoma stagnorum. 



,, plumbea Tomocerus plnmbeus. 



„ ambulans Lipura ambulans. 



„ globosa fusca Smyntburus fuscus. 



In 1783 0. Fabricius published^ a memoir on tlie 

 group, in wliicli lie describes seven species — P. humi- 

 cola, F. hypnorum, P. cincta, P. gigas, P. longicornis, P. 

 crystallina, and P. minutay the latter being, I think, 

 Papirms nigromaculatus. 



Fabricius, in 1793," places the genus Podura (with 

 Lepisma) at the head of the Stnistata, and immediately 

 before Ephemera, following Gryllus, with which he 

 closes the TJlonata. He records seventeen species, 

 which are the same as the first sixteen in Gmelin's ed. 

 of the ' Sys. Nat.' (with the addition of P. sigiiata), 

 and are described in the same words ; adding, how- 

 ever, the P. annulata and P. lignorum, which he 

 describes as " plumbea capite thorace pedibus furcaque 

 pallidis." This species, I think, it is impossible to 

 identify with any certainty. 



He describes the mouth of Podura as containing four 

 subclavate palpi, which is certainly not the case. 



Of Lepisma he describes five species, L. saccliarma, 

 polypoda, Uneata, villosa, and collaris, the two latter 

 being respectively inhabitants of China and the 

 American islands. 



In the year 1796 Latreille instituted the order 

 Thysanura, which he united with the "Paeasiti," 

 and placed after the Mites, at the end of the Aptero- 

 dicera, commencing the winged groups with the 

 Coleoptera. 



1 ' Kong. Danske Vid. Sels. Skr.,' 1783. 

 - ' Entomologia Systematica.' 



