274 Rev. A, E. Eaton on 



of Toulouse in 1880, I wrongly coupled together a defective 

 subimago of P. virgo, 01., and a nymph inhabiting the 

 Garonne, naming them Jolia roeseli in l88l. Professor Joly 

 could not show me the fly, which he had reared from nymphs 

 of that kind; but in 1905 an allied American species was 

 bred by Dr. J. G. Needham, Professor of Zoology at Lake 

 Forest College, N.Y., and was identified with the genus 

 named from the adult fly Chirotonetes, Etn. (1881). Simul- 

 taneously the nymph conjectured by me in that year to be a 

 Chiroionetes was shown by Dr. Needham to be an Ameletus, 

 Etn.. (1881). 



Polymitarcys sp. 



A subimago, ? of a small species, deprived of caudal setse. 

 Fore wing, not fully extended, about 13 mm. long, dull, 

 white, shaded very lightly from the costa to the radius, and 

 the strongest of the longitudinal veins faintly tinged with 

 reddish-violet grey; the remaining neuration whitish. 



Bab. Zungeru, N. Nigeria (Nov. 1910) ; J. W. Scott- 

 Macjle, 1911, 417. British Museum. 



Prep. Part of hind wing in Ca. balsam ; Etn. 



Polymitarcys sp. 



$ . — A larger insect than the preceding. Fore wing about 

 20 mm. long, dull, semitransparent, light warm sepia-grey, 

 with opaque neuration. Setse pilose. 



Bab. Usangu District, German E. Africa (Nov. 29- 

 Dec. 15, 1910). Alt. 3500-4500 ft.; S. A. Neave, 1911, 

 17, 7, British Museum. 



Prep. Hind wing in Ca. balsam; Etn. 



Ephemera, Linn. (1746), restricted Leach (1815). 



Species of this genus appear to be less constant in the 

 matter of wing-markings than has generally been supposed. 

 Specimens bred in cool waters are much alike ; but others of 

 the same species that have inhabited warmer lakes or ditches 

 might often be mistaken for quite different kinds at the first 

 glance, the spots in their wings being more numerous and 

 confluent, and the coloured edging of cross- veinlets broader 

 or more pronounced. Gregarince may even produce modifica- 

 tions of markings in the abdomen in individual flies. 



Ephemera sp. 



Imago S (dried). — Wings of a talcose gloss, transparent, 

 tinted very faintly with a brownish adumbration, especially 



