SYNOPSIS OF THE BRITISH EPHEMERIDJE. 31 



size and colouring, a further accurate investigation should be 

 made in order to confirm my conclusions. 



Synonyms for the imago are C. dipterum and C. mar- 

 inoratum, Curtis, Phil. Mag. 121, 1 ; and for the sub-imago, 

 according to the conjecture of Curtis, C. ohscurum, 121, 2. 



2. C. Rhodani, Pictet, Ephem. 248, 2, tab. 37—39 ; B. 

 horaria, Stephens, 66, 15, $ imago; B. veinia, Ste- 

 phens, 66, 16, 2 imago ; B. cingulata, Stephens, 67, 

 18, $ imago ; C. ockraceum, Stephens, Q^, 2, 2 

 imago; B. vermis, Curtis, Phil. Mag. 121, 11a. 



Imago. Head and thorax shining black ; the turban 

 of the eyes red ; abdomen pale brown, the tip darker ; 

 caudal filaments pale brown, with darker annulations ; 

 legs yellowish-brown, anterior legs dark brown ; anal 

 forceps pale, the thick basal joint brownish; penis 

 short, not visible externally ; wings hyaline ; costa 

 pale yellow, darker towards the apex ; apex of the 

 marginal field with numerous, irregular oblique trans- 

 verse veins, which are only here and there united to 

 form double cells. 



Females similar to the male; abdomen entirely dark 

 brown ; the paler caudal filaments more distinctly 

 annulated; ventral plate of the last segment two- 

 pointed and deeply incised. 



Length of the body ^ 3, $ 3.| lines ; expansion of the 

 wings (? 9, 2 9 lines ; setae <^ 9, 2 6 lines. 



Sub-imago of both sexes unicolorous grey-brown ; cau- 

 dal filaments unicolorous brown ; wing's srev, costa 

 rather darker, brownish. 



Habitat near London, Hertford ; May to July. 

 The description is made from English specimens; their 

 identity with C. Bhodani appears to me very probable, but 



