98 Bulletin Wisconsin Natural History Society. [Vol. 6, Nos. 1 — 2. 
FAMILY LIBELLULID^. 
SUB FAMILY MACROMIINAE. 
Introducing the third family of dragon-flies, the Macromiinae 
are unique among Odonates by having the triangle of the hind 
wings placed far beyond the level of the arculus. In this peculiar- 
ity the nymphs also take part, possessing a horn, pyramidal in 
shape, on the front of the head. Together with the Cordidinw 
the imagoes of the Macroniiijuc have a tubercle on the eyes be- 
hind. The males further resemble the Cordidiirm by the auricles 
on the sides of segment 2 of the abdomen and by the excavated 
anal margin of the hind wings. The Macromiince are composed 
for the greater part of large species that expand from 8o to no 
mm. They fly in the vicinity of their aquatic homes and are rarely 
captured far from it. Their wings are strong, their flight is reg- 
ular and well sustained. The two genera of the group separate, 
as follows : 
Eyes bareh' touching- ; occiput larger than vertex ; four to six cross- 
veins in the space above the bridge Didymops 
Eyes touching for some distance ; occiput smaller than vertex ; two 
to four cross-veins in the space above the bridge Macromia 
DIDYMOPS Eambur, Ins. New., p. 142, 1842 ; Needham, Proc. U. S. 
Xat. Mus. 26, p. 756, 1903 (Venation). 
The genus is represented by a single species confined to North 
America. At present it is not known to have been collected in 
Wisconsin, but from its occurrence in many parts of the Transi- 
tion and Upper Austral life zones it may be inferred that the 
species is native also in Wisconsin. 
Didymops transversa Say, Journ. Ac. Phila., 8, p. 19, 1839 ; Hag-en, 
Syn. Xeur. N. Am., p. 135, 1861 ; Needham, Bull. 47, N. Y. State Mus., p. 
481, 1901 (Bibliography & Desc. of nymph) ; Needham, Proc. U. S. Nat. 
Mus. 26, p. 711, 763, 1903 (Venation). 
Abd. male 37, female 39—40 ; h. w. male 33—35, female 37—38. 
Male. — Color brown marked with pale yellow. Face broAvn with a 
transverse greenish stripe. Frons with a black spot above. Thorax 
brown, a narrow antehumeral and sides each with a large broad stripe 
yellowish or white. Legs brown, feet black, tibiae yellowish above. 
Wings hyaline, bro^vnish at base, nervure brown, costa yellow, ptero- 
stigma brown. Abdomen brown, segments 7 — 9 laterally- expanded, the 
segments marked more or less with rings, 7 with a white ring- at the 
base prominent, laterally a spot at the base of 8, 10 entirely yellowish. 
Appendages yellow, longer than 10. 
Female. — Larg-er than the male. Wing-s with more brown at the 
base. The abdomen uniform, not expanded. 
Life Zone : Transition, Upper and Lower Austral. 
Time and Habitat — May to August about lakes. 
MACROMIA Rambur, Ins. Nevr. U. S. Nat. Mus. 26, p. 740, 1903 
(Venation) . 
