152 KEY. A. E. EATON ON KECENT EPHEMERID^ OE ilATFLIES. 



prevent leakage, and the caudal setae withdrawn more or less completely into the visceral 

 cavity. The terminal segment also is partly retractile. What appear to be the perineal 

 lobes form with the dorsum of that segment the extremity of the sheath of the setae ; 

 and whilst these are passing into its aperture during retraction, the fringes of each seta 

 collapse upon the rhachis successively. Dr. Vayssiere conducted me to the river at 

 Avignon, and captured a specimen without entering the water, — the only one that I have 

 seen alive. He reared the subimago early in June at Avignon, and states that the fly is 

 nocturnal. 



About fifty literary references to P.foliaceum are cited above ; of these only one relates 

 to the subimago and egg, aU the others to the nymph exclusively. The most important of 

 them are Vayssiere (1881 & 1882), Joly (1872, Sept.), and Westwood (1877, Oct.). This 

 catalogue of Prosopistoma literature is very nearly exhaustive, and although many of 

 the passages cited are tautological, yet the reiterated statements are not verbatim reprints 

 of one another. Some of the ' Notes ' designated by capital letters are special additions 

 to the extracts reprinted as ' Separates." 



Prosopistoma variegatum. 



Prosopistoma variegatum, Lat., Nouv. Aim. du Mus. d'Hist. Nat. (3), ii. 23(1833); Gueriu-Men., Ic. 

 Reg. An. iii. 40, pi. xxxv. 4 (1829-44); Westw., Proc. Ent. Soc. Lond. (1872), p. vi.; idem, Trans. Ent. 

 Soc. Lond. (1877), pp. 189-194, pi. iv. B 1-4. 



Hub. Madagascar. Length of body of nymph 6 millim. (Latr.). An undescribed 

 species. 



In accordance with my usual custom, I refrain from passing criticisms upon the work 

 of previous authors, preferring that it should be understood that where om- conclusions 

 may happen to differ upon any point concerning Prosopistoma, my not concurring with 

 their opinions respecting it is not due to oversight of their observations. 



