164 EEV. A. E. EATON ON EECENT EPHEMEEIDiE OE MAYELIES. 



the fore tibia olivaceous. In drying, the legs acquire yellowish amber tints. (The 

 alpine condition.) 



Length of body, d 6-8-5, $ 6-11 ; wing, 6-5-11 ; setse, c? im. 13-25, subim. 8-5, ? im. 

 11, subim. 8 mm. 



Hah. Spring-water streams in the mountains of Switzerland, N. Italy, Savoy, and 

 Central Italy: July to September. Thusis and Val Anzasca (M'^Lach.) ; near Cham- 

 p6ry, Valais, in streamlets having at altitudes of 3700-4000 ft., between 2 and 4 p.m. 

 in August, temperature ranging from 54° to 62° and 68° F. ; also at a spring in the same 

 neighbourhood at Les Clous (4000 ft., 6*50 a.m., 18 August, 1879, water 46° F. [large speci- 

 men]) : also near Samoens (2280 ft., 5-30 p.m., 13 Sept., water 54° F.) ; also in Val 

 Montjoie between Contamines and Notre Dame de la Gorge. Common in the Apennino 

 Pistojese near San Marcello, in streamlets tributary to the Limestre, both in the 

 chestnut wood below Gavinana (2550-2750 ft.), and at a streamlet crossing the highway 

 nearer San Marcello (2160 ft., 3-40 p.m., 27 July, '82, water 63° F.). The temperatures 

 quoted give suflB.cient indications of the water-climate suitable to the species, and may 

 be of use in the selection of sites for collecting. The Apennine specimens are just 

 appreciably brighter in the colour of their bodies than Alpine examples ; but the diffe- 

 rence is very slight indeed. 



Baetis atrebatinus, Etn. Plate LXIV. 15 (forceps). 



Baetis atrebatinus, ! Etn., Trans. Ent. Soc. Loudon (1870) 4; id., op. cit. (1871) 113, pi. v. 19, 19 a 

 [detail]. 



This species (living subimago Sf imago) closely resembles B. rhodani, but is dis- 

 tinguishable therefrom by the almost complete suppression of the usual projection in 

 front of the hind wing near the base of the costa, and by an acute prominent black point 

 in a shallow rounded depression in the protuberant part of the segment [probably the 

 point of the penis] above the forceps in the middle line of the venter. Length of body 

 7-8 ; wing 6-8 ; setae, 6 im. 11-13, subim. 8-5, ? im. 8-10, subim. 7-5 mm. 



Hab. England. The Kennet near Reading, Berkshire ; captured when in subimago 

 and at rest upon herbage fringing the towing-path of the canal between the mill and the 

 county bridge nearest the junction of the Basingstoke and Devizes railways : October. 



Baetis tenax, Etn. Plate LXIV. 16 (forceps). 



Baetis tenax, ! Etn., Trans. Ent. Soc, London (1870) 5; ! id., op. cit. (1871) 116, pi. v. 22, 23 a 

 [detail] . 



Imago {living). — 3 . Turbinate eyes intense warm sepia-, or chocolate-brown ; lower 

 eyes sooty-black. Notum jet-black. Abdomen in segments 2-6 translucent, tinted with 

 olive-brown, pale at the joinings and lighter towards the pleurae, with the tracheal trunk 

 slightly reddish-purple grey ; the other segments opaque : venter light cinereous, tinged 

 with orange in segment 9 between the forceps -limbs, and in part of segment 8, and 

 ochreous in segment 10. Forceps-limbs whitish, sometimes darker at the base. Setae 

 white. Femora olivaceous or dark olive-grey, pale yellowish at the knees ; fore tibia and 

 tarsus cinereous ; hinder tibiae and tarsi smoky grey, with the tarsal joinings either 



