322 KEY. A. E. EATON ON EECENT EPHEMEEID.E OK MAYFLIES, 



tip ; the forceps-basis is less deeply emarginate behind ; and in segments 8 and 9 the 

 venter is more of a light brown-ochre or " fuscous " in colour. Differences in the state 

 of preservation of the specimens may be held to account sufficiently for most of these 

 discrepancies, and individual idiosyncrasy for the remainder. From the coloration of 

 the abdomen of the adult fly, I am led to infer that the abdominal pairs of tracheal 

 branchife of the nymph are seven in number. 



P. 233, 1. 4 from bottom, /or tibia read tibise. 



P. 238, 1. 12 from bottom,/or Epeorus gbminus, sp. nov., read : — 



Epeorus stlvicola, Ed. Pictet. 



X Baetls sylvkola, ! Ed. Pict., Syuop. Nevropt. d'Espagne, 24, pi. iii. 7-12 (1865). 

 Heptagenia si/hicola, ! Etn., Trans. Ent. Soc. London (1871), 147. 

 Epeorus gemi litis, ! Etn., at p. 238, supra (1885). 



SuLimago (dried), $. — Wing-membrane sepia-grey; neuration for the most part (in 

 opaque view) pitch-black, the subcosta being so entirely, in both wings, but the proximal 

 ends of the other main longitudinal nervures become light bistre-grey, and the tegulae 

 are light yellowish : cross-veinlets in both wings narrowly and very faintly bordered with 

 light grey. Setse intense warm sepia-brown, with black joinings. Length of body, d 

 12, 2 13 ; wing d 15, $ 16 mm. 



P. 239, 1. 14 from top, after the parenthesis insert ; Spain, San Ildefonso, Segovia (Ed. 

 Pict.). M. E. Erey-Gessner lately transmitted to me for examination the type speci- 

 mens of this species ; and I have consequently been able to identify my Portuguese 

 Epeorus with Ed. Pictet's % B. sylvicola. 



P. 239, 1. 6 from bottom, /or 1835 read 1885. 



P. 239, 1. 7, add Also the Vosges (Puton, MS.). 



P. 212, 1. 14 from bottom, add Plate LXV. 13 ( d genitalia). 



P. 249, 1. 20 from bottom, for " anastomo seat all " read anastomose at all. 



P. 252, after 1. 20 from top, add :— 



Tgpe. Eh. semicolorata. Curt. 



Disiribuiion. N. America and Europe. 



Etfjinology . pelQpov, a stream, and ykvoc. 



P. 266, after 1. 16 from toj^, add : — 



Ti/2Je. H.fiavescens, "Walsh. 



Distribution. Northern Hemisjohere from about 30° N. lat. within the Arctic Regions. 



Etymology. eVra and yei'ea, in reference to the genus being seventh in a series. 



The following descriptions refer to the North-American species of Heptagenia {antea, 

 p. 266). 



Since tlie publication of the descriptions of IL. fiavescens and H. interpunctata, p. 266 

 and p, 267, a large series of the latter species and kindred forms has been added to 

 Mr. M'Lachlan's Collection. I have examined these, and I am led to suspect that the 



