SYNOPSIS OF THE BRITISH EPHEMERID^. 21 



tion very delicate, some straight transverse veins at 



the apex of the marginal field. 

 Length of the body $ 3| lines; expansion of the wings 



$ 4| lines ; setae $ 3J lines. 

 Habitat near London. 

 The description is made from English specimens. 



6. P. ERYTHROPHTHALMUS, Schrank ; Pictet, Ephem. 

 p. 222, 8, tab. 29 and 30 ; Eph. riifescens, Stephens, 

 59, 12, $, 2 imago. 



Imago. Head and thorax reddish-brown ; on the side 

 of the mesothorax is a sort of yellowish stripe ; abdo- 

 men reddish, the tips of the segments with a darker 

 transverse streak ; caudal filaments pale yellow, the 

 joints annulated with brownish-red ; penis pale brown, 

 of the form of a narrow oblong plate, the apex with 

 a triangular excision ; legs yellowish, the anterior pair 

 darker. Wings hyaline, the marginal veins yellowish ; 

 apical field with oblique veins and a row of double 

 cells ; the row of cells next the margin much smaller 

 than the others. 



Female very similar to the male, but the abdomen uni- 

 colorous and darker ; egg- valve projecting beyond the 

 anus, large, oval, the apex slightly emarginate. 



Length of the body $ 3|, 2 3| lines; expansion of the 

 wings ^ 8|, 2 8 lines; setae $ 5|, 2 3| lines. 



Sub- imago entirely yellowish-grey ; the caudal filaments 

 distinctly annulated with darker; wings unicolorous 

 ashy-grey. 



Habitat near London. 

 Pictet refers Stephens' Ephemera rvfescens to this species, 

 and probably he is right ; when I vras examining the Stephen- 

 sian types, I was not sufficiently acquainted with the dis- 



