EEV. A. E. EATON ON EECENT EPHEMEEIDJE OR MATELIES. 127 



fuscous, the segments sometimes each with a pair of short dark divergent lines followed 

 by two dots at the base, the 9th segment often brown-ochreous, with a longitudina 1 

 piceous streak along each side. Setre sopia-grey with darker joinings ; forceps testaceous 

 or greenish grey. Legs either almost sulphureous, with the fore tiliia lutescent and all 

 the tarsi testaceous ; or with the fore femur yellowish- or olivacoous-grey, the hinder 

 femora paler and tinged rather more with yellowish, the fore tibia dark olive-grey, the 

 tarsi and hinder tibiae grey ; a diffused obsolescent or nebulous rubigineous band is some- 

 times perceptible at the extremity of the femur, and the ungues are often piceous. 

 Wings vitreous, with the stronger nervures and sometimes the bulla almost faintly 

 piceous or amber-colour. 



? {living). — Eyes dark olivaceous ; vertex of head marbled with black, pale ochreous 

 or orange, and grey. Pronotum olivaceo-fuscous varied with pitch-brown. Meso- and 

 metanotum pitch-brown. Abdomen more opaque and tinged with dull greenish than in 

 the d' , but rather similar : the borders of the dorsal vessel dark. Legs olivaceous, the 

 femora with a grey band just before their pale distal extremity, the fore tibia sometimes 

 testaceous, the tarsi greyish. Wings much as in the c7 , but sometimes with the bulla 

 more distinctly coloured. The ventral lobe of the penultimate segment is slightly retuse ; 

 and the pleurae of the 8th segment are posteriorly acute. Eggs green, becoming browner 

 when dried. Length of body, s 6-9, 2 6-10 ; wing, 6 7-9, ? 7-5-11 ; seta?, ? im. 

 7 & 8-12 & 11, subim. 8 & 7 ; setse, ? im. 7 & 8-8 & 9, subim. 7 & 9 millim. 



Hab. Europe, from Portugal, near Cintra (300-400 ft. alt.), Madrid, and mid-Italy, 

 near San Marcello, in the Apenniuo Pistojese (2100-2700 ft. alt.), northwards to Great 

 Britain, and at least to Holland and Germany ; but the extent of its continental range 

 farther north and east is not yet ascertained. In England the fly is plentiful from June 

 till September ; but it was common at the end of April in Portugal. The nymph varies 

 greatly in colour ; the darkest and most strongly marked specimens are prevalent in 

 trout-streams, those of lighter colours in warmer streams and rivers, the variations being 

 largely determined by the nature of the bottom. I believe that Pictet was mistaken in 

 describing as distinct species merely colour- variations of this one ; and that some of the 

 differences indicated by him in the adult flies are attributable to the ordinary mutations 

 of colour undergone by them during their advance to full maturity, and during the 

 decline of life. The form of the forceps-basis in my earlier figure (1871) differs from 

 that in PI. XIV. 24 a, in the breadth of the extremity of the median projection ; but this 

 is only because the insect was then not adjusted so well for drawing as the more recent 

 subject. The part which is shaded thereabouts in the former figure was hidden when 

 the newer drawing was made, and the acute unshaded portion was brought into full view, 

 by throwing the extremity of the insect further back. 



Ephemerella inermis, sp. nov. 



Suhimago {dried). — Pore wings transparent, light brownish grey, with neuration in 

 some lights dull greenish grey, changing in other lights to duU light yellowish, the 

 membrane and opaque longitudinal nervures becoming dirty brownish white near the 

 wing-roots ; hind wings rather pale. Setse dark sepia-grey, with black joinings. Legs 



17* 



