274 EEV. A. E. EATON ON RECENT EPHEMEIIID.E OE MAYFLIES. 



greyish black nearly fi-om side to side ; segments 8-10 raw-sienna. Setae light brownish 

 ochre with dark joinings. Legs as in subimago, but with the fore tarsus sepia-brown, 

 dark at the tips of the joints. Wings vitreous, tinged with greenish yellow, esj)ecially 

 towards the fore costa ; longitudinal neuration blackish green ; cross veinlets, and the 

 bullae of tlie subcosta and radius, black. When dried the notum becomes light brownish 

 ochre; a small dark spot is visible on each side just above the hinder part of the insertion 

 of the hind coxa. Segments 2-7 of the abdomen are translucent whitish, with a 

 slight yellowish tint posteriorly and in the middle of the back, and are edged with light 

 bistre-brown nearly across their terminal margins ; their trachea? are white. Segments 

 8-10 arc bright brown-ochre. The fore wings are tinged with yellowish amber distinctly 

 tlu'oughout the submarginal area, and also in the uttermost extremities of the two 

 following areas ; in the marginal area the tint is mucli fainter. In, opaque vieio the finer 

 longitudinal neuration and the cross veinlets appear black or piceous, while the great 

 cross vein and the thicker nervures of the fore wing appear yellowish brown ; in tram- 

 mitted light the longitudinal neuration becomes yellowish amber, and the cross veinlets 

 remain black. The bulla of the subcosta is thickened for some distance, and black. 



Variation 1. 6 {dried). The wing-membrane is faintly tinged with yellowish through- 

 out the disk, and the stronger tint in the marginal area is as distinct as that of the 

 submarginal area. The ground-colour of segments 2-7 and 10 of the abdomen is 

 subopaque light yellowish approaching Roman ochre ; that of segments 8 and 9 light 

 reddish. Hub. Orthez. 



"^Variation 2 [yolitans]. Eyes of 6 blackisb brown. Notum atro-fuscous. Dorsum 

 of abdomen light bistre-brown, with the tips of the segments darker. Setae pale greenish 

 grey, with darker joinings. Hah. Kear Heading, Berks. 



$ [dried). Very similar to //. (jallica \ but the dark edging docs not extend the whole 

 way across the back along the terminal margins of segments 2-7, and the course of the 

 dorsal vessel is not marked out ; the main tracheae also are whitish or pale. Setae whitish, 

 with reddish joinings. Wings vitreous, tinged throughout the submarginal area of the 

 fore wing distinctly, and more faintly so in the marginal area flith yellowish amber; 

 neuration coloured as in the other sex ; the bulla of the subcosta is thickened, and 

 brownish or piceous. The median markings of the hinder femora are hardly perceptible ; 

 but close to the knee, very near the under edge of the femur, is a very small black 

 spot or dot. On the head is a black dot on each side of the vertex close to the eyes, and 

 another on each side below the eyes. Length of body 12-14 ; wing, 6 11j-15, ? 17; 

 setae, i im. 20-33, subim. 2i, ? im. 21 mm. 



Hah. England, near lieadiug, on the Kennet and Ilolybrook. Switzerland, at Basle 

 (M'Lacli.) and by the Lake of Geneva (Pict.). Erance, at Orthez (Basses Pyreuecfi). 

 June and July. The subimago emerges chiefly after sunset. 



I refer here as a variation the insect described in 1870 as a distinct species, — //. volitans, 

 — with some hesitation. The difference in the colour of the eyes is immaterial; the 

 coloration of the legs is favourable to their identity. The colouring of the body, 

 however, is a more serious obstacle to their union ; but it may not be insurmountable. 



