EET. A. E. EATOX OX EECEXT EPHEilEEIDj: OE MAYFLIES. 259 



PlHIThkogexa ArEAS'TiACA, Burmeister. 



X Bae'tis aurantiaca, Bunn., Haudb. d. Ent. Bd. ii. Abth. ii. 801 (1839) ; Pict., Hist. Xat. X'erropt. 

 ii. Ephem. 191 (1843-5) ; Walk., List of X'europt. Ins. in Brit. Mus. part iii. 560 (1853) ; Etn., Trans. 

 Ent. Soc. London (1871), 148 [note to Sraon. of Heptagenia iridana].—? B. j lateralis, Pict., op. cit., 

 pi. xsi. i. [nymph] (1843-5). 



Heptagenia aurantiaca, Meyer-Diir, Bull. Soc. Ent. Suisse, iv. 315 (1874) ; ! Eostoek, Jahresb. d. Ver. 

 f. Xaturk. Zwickau, 1877, p. 91 (1878). 



BJiithrogena [nympli], ! Etn., Ent. Mo. Mag. xviii. 24 (1881). 



Subimago {Uving), 2 . — "Wings usually griseous, seldom light sepia-grey, the hind 

 "vrings scai'cely, if at all, lighter than the fore wings ; wing-roots dull pale brownish- 

 yellow marked with a brown spot, the great cross vein similarly brownish ; neuration a 

 little darker. Setse griseous. Oculi subolivaceous or coesious, with a black transverse 

 line and a black moveable spot ; orbits of ocelli black ; a black line or triangular spot 

 extends from the base of the antenna almost to the orbit of the ocellus, and the facial 

 carina has sometimes a small black spot upon it. Pronotum pale, sometimes edged with 

 black ; a faint fuscous blotch at the front border of the mesonotum ; tegulae, a stripe in 

 continuation with them, the two longitudinal sutures of the mesonotum nearest to the 

 tegulae, and one or two lines on the pleurae in advance of the intermediate coxse, sub- 

 piceous or nigro-piceous ; a black spot on the foremost stigma ; a dark or black dot or 

 dash upon the outer proximal joining of the intermediate coxa, or in front of it, and a 

 spot upon the meso-pectus behind the coxa (or else a fine subpiceous line between the 

 coxa and the mesopectus in its stead) ; a black spot at the base of the hind coxa in front, 

 and another beneath at its tip ; trochanters black-pointed. Fore femiu: greenish grey, 

 black at the extreme edge of the knee above, and marked nearly in the middle with a 

 small black Y-shaped or triangular spot ; fore tibia blackish grey, black at the knee ; 

 fore tarsus and ungues black. Hinder legs lighter, but correspondingly marked. 



Imago {living), 6 . — Oculi commonly intense burnt-umber brown above and greenish 



grey beneath, divided either by a black transverse line or by a pale space edged with 



black ; sometimes the upper portion is fusco-olivaceous, and the lower csesious or cferu- 



lescenti-griseous ; in twilight, or by candle-light, the upper part appears greenish black. 



Occiput black ; face pale, marked, as in subimago, with fuscous or piceous. Thorax 



above varying from brownish yellow-green (pistazinous), or fuscous, or pitch-brown, or 



luteo-piceous, to pitch-black [changing to lutcous or luteo-piceous in dried examples] ; 



the metanotum black or piceous ; sternum concolorous with the mesonotum. Markings 



of the pleurtc and pectus, coxte, and femora very similar to the same in subimago ; 



ground-colour of the legs : — fore femur at first pistazinous changing to piceous ; tibia and 



■arsus in some lights darker, in others the tarsus is paler than the tibia, and its insertion 



s black : hinder femora at first almost greenish white, changing to light olivaceous ; 



ibiae paler, sometimes piceous at the tip ; tarsi smoky, or blackish grey, darker than the 



ore tarsus, with the incisures very narrowly black. Wings vitreous ; neuration either 



uscesceut or colourless, but the subcostal bulla piceous ; cross veinlets in the marginal 



jea of the fore wing usually quite simple, 2-6 (3 commonly) before the bulla very 



