324 EEV. A. E. EATON ON EECENT EPHEMEEID^ OR MAYFLIES. 



rowlv with bistre-brown on tbe dorsum, and with a lighter brown on the venter ; seg- 

 ments 9-10 and sometimes part of the preceding segment opaque light-yellowish ochre, 

 mingled on the dorsum with a paler yeUow. Setae, in opaque view, uniformly warm sepia- 

 brown. Coxge eoncolorous with the thoracic pleura. Fore femur, in opaque view, light 

 brownish olive, banded narrowly with blackish in the middle and close to the tip ; tibia 

 and tarsus somewhat of a medium sepia-brown, the tibia in some postures, however, 

 assuming the colour of the femur, with the insertion of the tarsus sepia-brown, and the 

 tarsus becoming very light sepia-grey : in transmitted light the femur and tibia are a 

 rich translucent yellowish or greenish amber ; the tarsus remains dull. Hinder femora 

 and tibiiB paler and more transparent than those of the fore leg ; during life the pigment 

 forming the femoral markings may perhaps be arranged in bands ; but in dried spcclnLens 

 these markings consist of a small grey median spot, and another just before the tip, 

 which is small, elongated, and blackish, and is flanked on each side by a very fine abbre- 

 viated black line in the edge of the limb. In some lights the hinder tarsi, and even the 

 tibise also, appear light brownish, or brownish grey ; in other j)Ostures only the tarsal 

 incisures are very narrowly brownish ; in transmitted light the femora and tibias become 

 whitish amber, and the tarsi with (sometimes) the extreme tips of the tibiae remain dull 

 or blackish grey. Wings vitreous : in the fore wing the membrane of the marginal and 

 submarginal areas, from the base to the beginning of the pterostigmatic region, is, for 

 the most part, sometimes colourless like that of the disk, but usually has a very faint 

 amber tint ; the remainder of these areas is suffused distinctly with transparent colour- 

 ing that varies in tint with change of posture from dull light reddish or reddish brown, 

 to bistre-grey or raw umber-grey, and this colouring extends further along the margin 

 to the extremity of the wing ; in the marginal area the same colouring becomes rather 

 faint near the costa. The markings of cross-veinlets in the fore wing are the same in 

 the adult as in the subimago, when there are any at all. Where in the subimago the 

 edge of the hind wing is black, it is not only so in the imago also, but the wing is there 

 bordered narrowly with a bistre-grey cloud, which is shaded off inside and gradually 

 diminishes in width posteriorly. Neuration of the fore wing in opaque view pitch-black, 

 excepting the stronger portions of the costo, subcosta, and radius, and also the basal 

 extremities of the other longitudinal nervures, which in some postures appear palei% or 

 light bistre-brown : in other p)ositions the neuration altogether, or else only the longitu- 

 dinal nervures, becomes translucent rufo-piceous. The pterostigmatic nervures are 

 simple and not crowded together. 



? . Very similar to the d , especially after oviposition : prior to this, the body is of a 

 richer yellow-ochi-e in its ground-colouring, and of course the abdomen is not translucent. 

 The marginal and submarginal areas are sometimes almost colourless ; sometimes only 

 the latter area, especially in the pterostigmatic region, is slightly amber-tinted, this tint 

 extending onwards along the margin to the extremity of the wing ; sometimes both 

 these areas and the colouring continued from them to the tip of the wing are light 

 amber-tinted, and a small reddish cloud lies between the costa and the radius at about 

 \ of the distance beyond the bulla towards the tip ; sometimes the reddish tint is as 



