SYNOPSIS OF THE BRITISH EPHEMERID.E. 13 



which have been compared with the types of the three 

 species mentioned by Stephens. In C. dimidiatay Stephens 

 says (head and thorax) "pitchy-black." I have observed 

 differences in the colouring and met with some darker speci- 

 mens, but never ** pitchy-black." Stephens does not mention 

 the dark base of the abdomen. Since his description was 

 made from dead specimens, these two circumstances are not 

 sufficient to prevent our uniting the species. The same re- 

 mark may be made with regard to C.pennata, and although 

 he here mentions a sub-imago, the description of C. brevi- 

 cauda appears to suit very well for the female sub-imago. 

 Curtis's description of C. viiiiima is too short to decide on 

 the species ; it is very possible it belongs here. 



Habitat London, Hertford, in June ; Cambridge, Whittle- 

 sea Mere, in July. 



The circumstance that C. hrevicauda and interjnipta are 

 found in the same localities and at the same time does not 

 prove anything for an identity of the species ; since C. haU 

 terata and dimidiata fly simultaneously in Prussia in the 

 same localities. 



C. Harrisella, Curt. Phil. Mag. 122,1; Steph. 61, 4; 

 is only made out from Harris's figure. Exposition, pi. 6, 

 f. 3. Harris figures a female sub-imago, which, according 

 to the size given, belongs to C. halter ata. 



The genus Palingenia, Burmeister, has simple eyes, four 

 dull wings with numerous transverse veins, three caudal 

 filaments, the middle one very short. The two European 

 species, P. longicauda and virgo, live in large sluggish 

 streams, whence they seem to be excluded from the English 

 Fauna ; moreover both species, by their size, their colouring 

 and their generally abundant occurrence, are so remarkable 



