4 INTRODUCTION. 



Linnaeus, in the first edition of the ' Fauna Suecica,' 

 described nine species of Poclura, namely, P. viridis, 

 atra, globosa fusca, teres jjlumbea, nivalis, arhorea nigra, 

 aquatica nigra, viatica, and terrestrls alba. 



P. 'oiridis seems undoubtedly to be our Smynthurus 

 viridis. P. atra is more doubtful ; his description is, 

 " P. atra, abdomine subgloboso, antennis longitudine 

 corporis ; apice albis." In the ' Systema Naturae,' on the 

 contrary, these characters are given under the name 

 of P. ])olypoda, and P. atra is made synonymous with 

 De Geer's P. fusca. On the whole, I am disposed to 

 regard the P. atra of the ' Faun. Suec. ' (P. polyjjoda of 

 the ' Sys. Nat.'), as our Pajpirius polypodus. This species 

 occurs in Sweden, whence M. Tullberg has been 

 so kind as to send me some specimens. It has white 

 tips to the antennae ; but, on the other hand, in this 

 country it is rather violet than black. 



P. globosa fusca nit id a is, in all probability, our 

 Smynthurus fuscus. P. teres plumbea has been generally 

 regarded as the species which must, I think, now bear 

 the name of Tomocerus plumheus. It has been so consi- 

 dered by most of those who have written on the group, 

 but the determination seems to me very doubtful. 

 P. nivalis is still known by the same name. 



P. arborea nigra is probably the Isotoma arborea of 

 subsequent writers. P. aquatica is also still known 

 under that name. It is impossible satisfactorily to 

 identify the species described under the name of I. via- 

 tica, but most writers have denoted a small black 

 species of Isotoma by that name, and they are probably 

 correct. 



Lastly, the P. terrestris alba has given rise to great 

 confusion. In the second edition of the ' Fauna Suecica,' 

 and in the ' Systema Nature,' this sjDccies is described as 

 P. flmetaria. It is clear, however, that the P. fimetaria 

 of the 'Faun. Suec' is not the P. fimetaria of the ' Sys. 

 Nat.' Of the former, Linnasus says that " infinita 

 copia occurrit, et atomorum volitantium instar saltat," 

 and he describes it as " omnium minima, totaquc alba." 



