1907.] 107 



iiw.ay down the field in an easterly direction, the same as that taken 

 by the larger species. Whilst the flight was going on a few of them 

 paddled about on the surface in a sort of dance, but these did not 

 seem to fly away like those which came straight up from the bottom 

 of the [)ond. No migration of any sort was going on in other ponds 

 in adjacent fields. 



1 have always understood that these small ponds were believed 

 to be stocked with water-beetles (and I suppose any other winged 

 water insects such as water-boatmen) by immigrants flying from other 

 [)ieces of w%'iter, but I have not come across any account of a migra- 

 tion such as the present one, though it must surely be of not infre- 

 quent occurrence, and likely to be observed by those who keep their 

 eyes open for such things. 



Montevideo, Chickerell, near Weymouth : 

 April, 1007. 



THE BRITISH PLECOPTERA (PERLIDMJ. 

 BY K. J. MOBTON, P E.S. 



The following short sketch of our knowledge of the British 

 Plecoptera has been suggested by some enquiries that have reached 

 me, reminding me that a good deal of recent information concerning 

 our species has never been noticed in any of the British Entomo- 

 logical publications. In the genus Nemoura, in |)articular, several 

 changes and additions have to be recorded ; but it may be of use to 

 run over all the genera. 



Bictyopteryx.— lLyvo species appear in McLachlan's Catalogue of 

 1870: mio-ocephala and rectangula. The latter, according to examples 

 named for me by him, seems to be quite the same as what he called 

 microcepTiala, the individuals referred to having merely a somewhat 

 simpler nenration than is usual, and as far as I can say with certainty 

 at present, only one species of Dicfyopterijx (in the restricted sense) 

 occurs in Britain. I have seen it in many examples from highland 

 lakes and lowland rivers in Scotland, and from the Severn, the Kennet, 

 and the Test in the South. All these British insects were at one time 

 considered by Klapalek as rectangula and different from microcephala ; 

 but he now regards a South European insect as the true rectangula, 

 and he has recently described our species as new under the name of 



