SYNOPSIS OF THE BRITISH EPHEMERID^. 29 



1. C. DiPTERUM, Linne ; Pictet, Ephem. 266, 11, tab. 42; 

 C. dipterum, Stephens, 68, 1, 2 imago and sub- 

 imago ; Bph. hehipes, Stephens, 59, 14, 9 imago ; 

 Eph. apicalis, Stephens, 59, 11, $ imago; Baetis 

 cuUciformis, Stephens, QQ, 14, (^ imago. 



Imago. Head and thorax black-brown ; eyes black, 

 the turban-like part red ; abdomen pale fawn-colour ; 

 the four last segments brown ; anal forceps white ; 

 caudal filaments white, the joints and a slender ring 

 in the middle of the joints blackish ; legs yellowish ; 

 wings hyaline ; venation fine, whitish; in the apical 

 portion of the marginal field are some straight trans- 

 verse veins; posterior wings wanting. Female very 

 diff"erent from the male, reddish-yellow ; eyes blue ; 

 on the crown and prothorax are two small reddish 

 streaks ; abdomen with a brown raised spot on the 

 side of each segment and a dot in the middle ; egg- 

 valve with oval tip, entirely cleft ; legs yellowish ; 

 before the tip of the anterior femora is a red spot ; 

 wings hyaline, the costa to a little beyond the second 

 marginal vein yellowish-brown, marbled with white 

 spots. 



Length of the body (^ 3, 2 2| — 3| lines ; expansion of 

 the wings $ 8|, 2 7|— 10| lines; setae ^ 9, 2 6J 

 lines. 



Sub-imago $ . Eyes black ; turban orange ; head and 

 thorax dull brown-grey ; meta thorax pale brown ; 

 abdomen grey, the points and sides, together with the 

 last segment and the underside, paler; anal forceps 

 grey ; caudal filaments grey, the joints darker ; legs 

 dull yellow, the tip of the femora and tarsi darker; 

 anterior legs greyish-yellow, the femora above and 

 the tarsi darker ; wings ashy-grey. 



