260 EEV. A. E. EATON OX RECENT EPIIEJIERTDiE OE MAYFLIES. 



faint, 1 (rarely 2) at or near the bulla, and 10-19 (usually about 16) beyond it better 

 developed. Abdomen above fuscous or pistazinous, the segments narrowly darker 

 immediately before their pale extreme apical edges, their sides paler and eoncolorous with 

 the venter ; in segments 2-7 from the lateral line near the base of the segment on each 

 side of the dorsum a dark fuscous stripe (sometimes black towards its origin) ascends 

 obliquely, growing gradually lighter and less defined, and blends with the dark colouring 

 along the midst of the posterior border of the segment ; these stripes are most strongly 

 marked in the binder segments. Venter in the anterior segments spotless, pale or 

 cinereous, in 7-10 more or less lutescent or orange-tinted ; forceps black or greenish 

 black, paler inside distally ; penis testaceous. Sctic sepia-grey, becoming whitish 

 distally, sometimes black close to their origin ; a few of the joinings near tbe base 

 black. 



$ (living). — Mai'kings similar to those of the subimago. . Oculi subglaucous, with 

 Iheir orbits and the line across subpiceous. Ground-colour of thorax light fusco- 

 olivaceous ; the oblique abdominal stripes are sometimes abbreviated, the stigmata 

 marked with a dark dot. Wings and neuration colourless. Fore tarsus eoncolorous 

 with the tibia, its joints narrowly edged above at the tips with blackish like those of tbe 

 binder tarsi, whose ungues are sometimes slightly rubiginose. Venter pale ochraceous ; 

 setae sometimes greyish white, sometimes greyish ; ventral lobe slightly excised. In 

 other respects similar to the j . 



Dried specimens have the main nervures of the wings pale amber-colour, tbe great 

 cross vein of the fore wing blackish or piceous, the costa beyond it greyish, and the 

 bulla black ; the cross veinlets remain pellucid as a rule. In some specimens the hinder 

 tarsi are a shade darker tban the tibia;. The lateral stripes of the abdomen sometimes 

 are reduced to spots, and sometimes are almost obliterated. Length of body 6-5-9 ; 

 wing 7-10 ; setsD, d im. 11-15, subim. 0-5, $ im. 9-10, subim. 6-5 mm. 



Hab Common on the continent, in rivers and streams, from Holland and Germany 

 southwards to Switzerland, the Pyrenees, and Portugal, c. g. at the following places : — 

 Aruhem, Ilalle, Dresden; Basle, Berne, Versoix ; Brive, near Le Puy (Haute Loire), 

 Toulouse, Tarascon (Ariegc), Orthcz ; and Ponte de MarccUos (Beira Baixa). 



Herr Eostock's identification of this species with Burmcister's %B. aurantiaca appears 

 compatible with the latitude of interpretation allowed to the descriptions of more than 

 forty years' standing. Burmeistcr omits to mention the conspicuous dark spots on the 

 femora ; but Pictet did just the same thing with respect to those of the preceding species ; 

 and therefore no stress need be laid upon the omission. 



IIhithrogena gekwanica, sp. nov. Plate XXIV. 43 h (penis dried). 



Imago [dried), d . — Notum pitch-brown anteriorly, pitch-black posteriorly. Abdomen 

 fusco-piceous or piceo-fuscous, paler by the dorsal joinings. Seta3 fuligiueo-piceous. 

 Pore femur piceous ; tibia fuligineo-piceous. Uindcr femora piceo-lutescent, each with 

 a dark median band, the trochanters rather lighter; tibite light yellowish amber; tarsi 

 fuscescent, with piceous ungues. Wings vitreous, tinged slightly with light olive-grey 



