. Bulletin - New York State Museum. Science. MAY FLIES AND MIDGES OP NEW YORK 21 of the venation are easily learned, and afford a ready clue to the relationships. Eaton says, " Unstable in minutiae, so closely is the essential plan of the neuration adhered to by nearly related mayflies that the general facies of the wing is an important aid to their classification, affording characteristics as easily recog- nizable as the style of branching in the case of ; By reference to , 2 or 3, or any of the wing figures of the plates, it will be observed that there are three nearly
. Bulletin - New York State Museum. Science. MAY FLIES AND MIDGES OP NEW YORK 21 of the venation are easily learned, and afford a ready clue to the relationships. Eaton says, " Unstable in minutiae, so closely is the essential plan of the neuration adhered to by nearly related mayflies that the general facies of the wing is an important aid to their classification, affording characteristics as easily recog- nizable as the style of branching in the case of ; By reference to , 2 or 3, or any of the wing figures of the plates, it will be observed that there are three nearly parallel veins extending along the front or costal margin of the wing, costa (C), subcosta (Sc)^ and radius {R^). These three are fol- lowed by three forking veins that occupy the greater part of the wing area, the radial sector (Rs), the media (M) and the cubitus (Cu). The middle one of these, the media, forking usually far-. rig. 2 Wings of Callibaetis ther outward than the others and being more constant in form, is one of the best landmarks of the wing. All that lies between it and vein R^ is radial sector, which, in the fore wings of may- flies, is entirely detached from the radius and functions as a separate vein. The only place in the series where there is likely to be any difficulty in recognizing the media is in the few genera closely allied to Baetis (see ) in which both tlie media and the cubitus are apparently simple; but it will be readily observed by carefully noting the number and relation of the longitudinal veins that the hinder branch of the fork of these two veins is detached, and appears as an independent sector standing on the hinder side; the relative lengths of these veins enable one to recog- nize them all, even when detached, or when, through shifting of cross veins at their bases, they appear to have formed attach- ments of a contradictory sort (see vein CiCo in , ). These. Please note that these images are extracted from scanned page imag
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