EEV. A. E. EATON ON EECENT EPHEMEEID.E OR MAYFLIES. 49 



in several other burrowing nymphs) each with a minute tubercle ; the divisions of the 

 minute gills of the first segment are linear and fringeless ; those of the gills of the 

 other segments are larger, and are flat, ovate-lanceolate, acuminate, fringed, membranous 

 laminae. Wings aduate to the notum along their inner margins only. Pronotum large, 

 quadrangular, ciliated at the sides, which are nearly straight ; its border in front and 

 behind slightly thickened, and armed at the fore corners with single triangular points 

 projecting forwards. Seta? acuminately plumose, a little more than half as long as 

 the body. Ventral segments 7-10 of the abdomen, taken together, are about If as 

 long as the rest put together. 



Tyi^e. H. hillneata (in % Baetis), Say. 



Distribution. Amei'ica, from Canada to Brazil ; also India. 



Etymology, eg and jeved, on account of its being the sixth of the Sections of Paliiigenia 

 cmctor'um defined by Hagen in 1863, and named by Walsh in that year. 



The species of this genus and of Ei)hemera might be described concisely from living 

 specimens. 



Hexagenia albivittata, Walk. 



XBaetis albivitta , ! Walk., List of Ncuropt. Ins. in Brit. Mus. part iii. 566 (1853). 



Pallngmia continua, ! id., Trans. Ent. Soc. London, n. s. v. 199 (1860) . — P. dorsigera, ! Hag. MS. (1861) . 



Hexagenia albivitta, ! Etu., op. cit. (1871), 64, pi. iv. 2, 2a [details] ; Hag., ojj. cit. (1873), 392. 



Suhimago {dried). — Wings transparent pale smoke-grey with opaque black neuration ; 

 but the main nervures are pale near the base of the wings and in the hinder portion of 

 the disk of the hind wings, with the exception of the subcosta of the hind wing, which is 

 black up to the wing-roots. 



Imago {dried). — Body above snow-white varied with black ; the black forms a broad 

 longitudinal stripe on each side of the pronotum, and encloses a large somewhat mitri- 

 form blotch on the meso- and metanotum ; white predominates upon the dorsum of the 

 abdomen, leaving a serrated black stripe above the spiracular line on each side (composed 

 of a series of triangular spots, each with its hypotenuse descending obliquely from the 

 hinder margin towards the lower anterior angle of the dorsum of the segment) and en- 

 closing some small black intermediate markings in the anterior portion of some of the 

 segments, viz. : — in both sexes a short longitudinal linear streak adjacent to the dorsal 

 vessel in the last few segments, and in the ? in each of the segments 3-6 a pair of 

 similarly situated triangular streaks, whose apices coalesce somewhat with the tips of the 

 serratures of the lateral stripes ; venter pale dull reddish sepia-brown with a longitudinal 

 median testaceous streak, and with darker tips to the segments, or, in very faded speci- 

 mens, pale dull lutescent with the overlapping borders of the segments paler. Seta? 

 either fawn-colour banded with brown, or brownish with irregular dull yeUow-ochreous 

 bands. Wings in c? perspicuous, faintly tinted with very pale sepia-grey, paler in the $ ; 

 neiu^ation pitch-black. Legs in ? lutescent, the hinder tarsi with the terminal joint 

 and ungues, and the extreme apical borders of the paler other joints reddish sepia-brown : 

 the fore legs in d fuscescent, with all of the tarsal joints but the Jast black. Length of 

 body 15 ; wing, d 15, ? 17 ; setse, s im. 35, subim. 23 mm. 



SECOND SERIES. — ZOOLOGY, VOL. III. 7 



