Dceember, 1S98.] LJCLLr ^^ lc8o 265 



EPSEMEEID^ TAKEN BY MR. McLACHLAN IN THE DISTRICT OF 

 THE LAC DE JOUX (SWISS JURA) IN 1898. 



BY THE EEV. A. E. EATON, M.A., F.E.S. 



[The insects noticed below were taken during a stay in a little- 

 known corner of the Canton Vaud from July 25th to August 10th. 

 No systematic search for EpJiemeridce was attempted. Some general 

 notes on the district will be given later when dealing with another 

 group. — E. McLachlan]. 



EpHEMEEEiLA IG-NITA, Poda. — 2 ? im., rather small. 



C^Nis DIMIDIATA, Steph. — 6 examples, not all adult. Abundant at Lac Brenet. 

 Baetis ehodani, Pict. — 1 $ im. 

 Baetis sp. ?. — 1 ? im., fragmentary. 



Baetis nubecularis, sp. nov. 

 1 S im., defective in legs and setse. 



Imago (dried) ^ . Thorax above pitch-black ; at the sides browner and varied 

 with a lighter colour. Abdomen pitch-brown ; after the 6th segment opaque, but 

 anteriorly translucent with narrowly opaque joinings. Setse whitish sepia-grey, the 

 joinings from certain standpoints simply opaque or else darker grey. Fore-leg 

 pitch-brown ; the femur towards its lower edge lighter or translucent. Wings 



vitreous ; the fore-wing (as shown in 

 the annexed figure) tinted for some 

 distance at the apex with light pitch- 

 grey, and this more distinctly in the 

 pterostigmatic region,and the adjoining 

 portion of the submarginal area, than 

 elsewhere ; the stronger neuration pi- 

 ceous or bistre-brown, the two exterior ranks of cross veinlets anterior to the 

 prsebrachial nervure being of the darker tint. Length of wing, 7.10 mm. 



Hab. : Source de I'Orbe, Canton Yaud ; I J" im., August 2nd, 

 1898 (McLachlan) . The clouding of the wing is analogous to what 

 is seen in the North American Blasturus nebulosus, but is less rounded. 

 In being particoloured the wing differs from that of all other known 

 European species of the genus. 



Epeoetts assimilis, Etn. — 19 $ im. Absolutely swarmed along the road between 

 the Source de I'Orbe and the town of Vallorbe on the afternoon of August 3rd, 

 during a succession of violent thunderstorms. 



Rhithhogena semicoloeata, Curt. — 3 <? , 1 $ im. One <? has the wings hardly 

 at all tinted ; another $ exhibits typical colouration, and is matched by 

 the $ ; the third $ is of the variety described as " Variation I " (the semi- 

 colorata of Pictet, not of Curtis) in Trans. Linn. Soc. London, ser. 2, Zool., 

 vol. iii, p. 257. 



Ruitueooena aueantiaca, Eurui. — 1 <J im. 



