editor of this edition, misnamed the March Brown 

 Baetis longicauda thus associating it with 

 another and quite distinct insect. Eaton, in his 

 monograph on Recent Ephemeridae, wrongly 

 united longicauda and venosus under the name 

 venosus, as one and the same, transferring them 



By permission of AXXALS AND MAQAZLSE OF NATURAI 

 Fig. 1. Rhithrogena haarupi 



to the genus Ecdyurus, and the March Brown has 

 been known as Ecdyurus venosus ever since. 



Mr. K. G. Blair, in 1931, separated the two 

 species again and proved that Ecdyurus longicauda 

 was in fact the Autumn Dun. 



Ecdyurus venosus differs in its habits from the 

 true March Brown. The latter insect appears on 

 the water during early spring in great numbers 

 in a succession of hatches throughout the day. 

 One moment there is not a fly to be seen : the 



