8 Rev. A. E. Eaton on New British EphemcridcB. 



greenish-olive, ^vith blackish tarsi. Abdomen sub-oliva- 

 ceous, with dark oblique lateral streaks; beneath, each 

 segment has in the middle of the base a short black acute 

 isosceles triangle, whose extreme apex is remotely flanked 

 by a short diverging line on either side, which lines are 

 followed each by a dot, and in a line both with these two 

 dots and two lines respectively is a short line on each 

 side close to the edges of the ventral region of the seg- 

 ment. Setae black, piceous towards their tips. 



Length of body, S 11-12, ? 12-14; fore-wing, $ 13- 

 17, ? 13-15; set. r^ 22-33, ? 20 mm. 



Hah. — The Dart, the Kennet, and the Trent. May to 

 August. 



This species closely resembles the Alpine H. montana, 

 Pict., which, however, has blue eyes. The name which 

 I have given it has reference to the neat ventral markings. 



I am preparing for publication figures of the special 

 structures of these and of many other British and foreign 

 species of Ephemeridce. 



