258 EEY. A. E. EATOX ON EECEXT EPIIEMEEID^ OE MAYFLIES. 



a distinctly defined cloud of deeper tint than tlie colouring of the typical specimens — in 

 fact, sometimes a medium raw-umber brown cloud. Legs darker than in the typical race : 

 vjhen dried the fore femur becomes raw-umber brown, and the tibia and tarsus light 

 pitch-brown, with the insertion of the latter dark ; femoral streak distinct. 



Variation 2. — The whole of the membrane of the fore wing is tinted with dull rusty 

 yellow, and the colouring in the basal half is scarcely, if at all, darker than in the 

 remainder, although, when the wings are erect, it may apparently be so where the hind 

 ^viIlgs underlie the others. Notum brown-ochreous. Legs lighter than in the typical 

 race ; femoral streaks distinct but rather small. 



9 {licing). — Eyes olive-black. Dorsum of the abdomen intermediate in tint between 

 yellow-ochre and raw-sienna, very pale by the joinings ; venter very light Mars-yellow ; 

 lobe of the ninth ventral segment emarginate. Legs golden-brown or brown-amber ; the 

 fore tibia and tarsus, the hinder tarsi, and the bases of the hinder tibise tinged Avith 

 olive-grey ; the femoral spots or streaks, the femoral tracheae, and the points of the 

 trochanters black. Wings vitreous, colourless or almost colourless : in opaqtte view the 

 stronger of the longitudinal nervures appear to be subtestaceous or rusty yellow, the 

 finer nervures piceous, and the cross veinlcts black ; in transmitted light all of the 

 neuration appears subtestaceous. 



Variation [the semicolorata of Pict., not of Curt.]. — The colour of the wings resembles 

 that of Variation 2 of the other sex. 



Length of body 7-11 ; wing 7-12 [usually 10-12] ; setae [of the larger specimens], 

 6 im. 23-28, subim. 8-9, ? im. 14, subim. 10 mm. 



Eab. Europe, from Js'orway (WaUengren) southwards to the Alps and Pyrenees. 

 The typical race is common in Great Britain from June to September, frequenting trout- 

 streams and the swift parts of rivers ranging in temperature during the summer from 

 about 51° to 58° E. In Cumberland, on Cross Eell, it ascends to about 1500 feet. The 

 same race occurs on the continent in Belgium, Erance, Saxony, Switzerland, Bavaria, 

 northern Italy, and (Zeller, in M^Lach. Mus.) Cariuthia, e. g. at the following localities : — 

 the stream at Yersoix in June (Pict.) [uj)wards of 1250 ft., water 58° F. in the afternoon 

 of August 24th] ; Morillon near Samoens [2200 ft., water 50° E., 4-6 p.m. August 30th]; 

 between Partenkirchen and Mitten wald in Bavaria ; in the Ortler district, both in the 

 Val Eurva above S'" Caterina [6300 ft., water 59° E., July 28th], and in the Val Mazza 

 near Ponte di Legno [5800 ft., water in the Oglio 49° E., but 56° E. in a tributary torrent 

 at the same place, July 29th, in the afternoon] ; along the Neez, above the Pont d'Oly, 

 near Jurancon, Pau [about 600 ft.] ; on the road to the Col des Tontes from Eaux Bonnes 

 [3220 ft.] ; and at the outlet of the Lac d'Aious [5945 ft.]. 



Variation 1 is represented in M'^Lach. Mus. by specimens from Autun, Gex (Ain), and 

 Neuchatel. According to Pictet it is common in the neighbourhood of Geneva, at 

 streams, and is wont to appear in large numbers before rain or thunder-storms in sum- 

 mer. Variation 2, in the same collection, is ticketed Carintbia, May 27th (ZeUerj. 

 Pictet makes no mention of the femoral markings. 



