276 Rev. A. E. Eaton on 



with grey-black and skirted by a narrow edging of a smoky 

 tint shaded off inwards ; most of the longitudinal veins in the 

 hind wings white. Abdomen probably yellowish white, 

 with black markings, a somewhat serrated stripe on each 

 side of the dorsum being the principal. Fore legs opaque, 

 subluteous ; hinder legs of a lighter yellow, especially the 

 tibias ; ungues and joinings of their tarsi dark. 



Length of fore wing about 27 mm. 



Hah. British E. Africa, Ilala, Maramas Dish, 14 miles E. 

 of Mumias, 4500 feet alt. (June 18-21, 1911), S. A. Neave ; 

 1912, 20, British Museum. 



Hexagenia, Walsh (1863). 



All species previously known are natives of N. and S. 

 America and Asia respectively. 



Hexagenia (?) illustris, sp. n. 



Abdomen from the side, showing lateral markings of the dorsum ; the 

 median seta (rudimentary), part of a lateral seta, and a limb of the 

 S forceps in dotted outline out of focus. Part of forceps ; the 

 apical joint of one of them from a different standpoint ; and the base 

 in profile of an outer caudal seta, on a uniform larger scale than the 

 former detail. 



Hexagenia illustris, sp. n. 



Imago <$ (dried). — Dorsum ivory-white down the middle, 

 with black lateral markings above the spiracular line on the 

 abdomen (see fig.) ; a broad fuscous stripe along each side of 

 the meta- and mesonotum, black on the pronotum, and the 

 pleura, below that, black as far as the insertions of the legs. 

 Head black ; the space between the antennas besides their 

 first two joints whitish. The abdomen has in addition a fine 

 abbreviated transverse line in the middle of the dorsal base 

 of segment 9, a small triangular spot in segment 8, and a 

 short acute triangular streak in segment 7, barely indicated 

 in segment 6, all in corresponding positions, blackish. Venter 

 spotless, except the joining at the base of segment 9, and, close 



