248 EEV. A. E. EATON ON EECENT EPHEMERID^ OE MAYFLIES. 



CiNYGMA INTEGRUM, sp. iiov. Plate LXV. 4 (genitalia). 



Subiniago {dried). — Wings transparent brownish grey, approaching light Cologne- 

 earth ; the hind wings lighter than the others, approacliing whitish Cologne-earth grey : 

 neuration inconspicuous, suhopaque ; the costa pale at the roots. Abdomen bistre-brown 

 above, varied in segments 2-7 with very light brown-ochre ; the darker colour borders 

 the terminal margins of these segments broadly, excepting at the pleuraj, and in each of 

 them is produced forwards to the base of the segment, both as a narrow strij)e along the 

 track of tlie dorsal vessel, and also as a broad longitudinal stripe through the midst of 

 each side of the back; and conversely an oblong spot of the lighter colour extends from 

 the base some distance along the pleurae on each side of the back, and a narrower spot 

 saliently curved externally reaches from the base some distance along each side of the 

 dorsal vessel ; venter unicolorous, very light brownish ochi'e. 



Imago {dried), d . — Notum light pitch-, or Vandyke-brown. Abdomen in segments 

 2-7 translucent, light Vandyke-brown, opaque at the joinings above the pleura?, and with 

 three slightly darker longitudinal stripes from the hinder border of each of these 

 segments, viz. : — one coincident with the track of the dorsal vessel, which is intersected 

 lengtliAvise by a fine pale median line, and is sometimes only very faintly indicated, and 

 another rather broader and darker stripe on each side of that, falling short of the base of 

 the segment and vaguely delimited along its upper side ; moreover the trachea? are dark : 

 in segments 8-10 the prevailing colour Ijecomes modified either with light burnt-umber 

 or with opaque burnt- sienna or brown -ochre, while the median stripe is posteriorly 

 obliterated more or less in every segment, and iu segments 8 and 9 the lateral stripes 

 attain the base. Venter spotless, in segments 1-G light Vandyke-brown, in the hinder 

 segments light burnt-umber, approaching opaque Inirnt-sienna. Setae very light bistre 

 or whitish bistre-grey. Pore femur and tibia in ojxique view light bistre-brown, witli the 

 insertion of the tarsus black, and with two broad indistinct obscure bands on the femur 

 (one just before, and the other just beyond the middle) ; tarsus in some lights whitish 

 brown-oclire, in other lights bistre-grey, or nearly concolorous with the tibia ; in trans- 

 mitted light the femur and tibia acquire a light brownish amber tint. Hinder legs 

 lighter than the fore leg, the femora each with a single brown indistinct dark band 

 beyond the middle, the tibiae in opaque view whitish brown-ochre, and the tarsi either 

 concolorous with the tibiae or in some lights greyish or light brownish : in transmitted 

 light the femora become light yellowish amber, and the tibia? whitish amber-coloured. 

 Wings vitreous ; the pterostigmatic region of the fore wing (tinged, like the mem- 

 brane just at the roots, with extremely light bistre-grey) contains evenly anastomosing 

 cross veinlets : neuration pitch-brown. 



? . Very similar to 6 ; but the notum is of a light yellowish browu approaching light 

 brown-ochre, the setae whitish brown-ochre, the femora of some examples more strongly 

 coloured than in 6 , and the tibiae in opaque view dull light brown-ochre. Length of 

 body, 6 11, $ shrunken ; wing, d 12, ? 10-13 ; setae, 6 im. upwards of 25, S im. 

 16-20 mm. 



Kah. Washington Territory, and Mt. Hood, Oregon (M'Lach. Mus.). 



