THE MAYFLY 25 



times an abbreviated thin streak on each side 

 of the dorsal vessel, at the base of the segment, 

 i\> flanked by a longer and broader tapering 

 streak (represented sometimes by a triangular 

 spot in the anterior segments), which does not 

 extend either to the side or to the hind margin 

 of the segment ; sometimes these markings 

 coalesce, so as to leave an ivory-white triangle 

 pointing forward upon the middle of the hind 

 margin of the segment. Ventral markings, a 

 pair of longitudinal linear brown-black streaks. 



" This species usually inhabits colder and 

 swifter waters than Ephemera vulgata. It is 

 abundant in Dovedale, Derbyshire, and in many 

 streams in the North of England. In Dorset- 

 shire it inhabits trout streams and the River 

 Axe. It would probably be found in the 

 Itchen, and it may occur in the Test above 

 Romsey. It is the mayfly of anglers in trout 

 and grayling waters." 



I would supplement the above remarks by 

 stating that I have found Ephemera danica on 

 the Test, the Itchen, the Taw. It is at times so 

 plentiful on the Rennet that in the neighbour- 

 hood of Thatcham the Great Western trains 

 have been invaded, and these prolific insects have 

 been found in the railway carriages. On Lough 

 Arrow, near Boyle, in Ireland, vast numbers 

 appear, usually earlier than on south-country 

 streams. In this lake not only do the very 

 largest trout, fish up to 10 lb., feed upon the 

 spent imagines, but flocks of sea-birds are 

 attracted by their advent, and I have seen 



