84 Bulletin Wisconsin Natural History Society. [Vol. 6, Nos. 1 — 2. 
form — apically — of the eighth segment of the abdomen. Mr. Need- 
ham has accordingly grouped the species into four sub-genera, 
Gomphiis, Gomphiirus, Styluriis and Arigomphtis. Grouping 
known species and such Hkely to be found within the state under 
these sub-generic names the result for Wisconsin is ten species of 
Gornphus, four of GompJiiirus^. one of Styhirus., and four of Ari- 
gomphus. For distinguishing the sub-genera the following table 
is appended: 
1. Tvvo cells between veins Al and A2 at their origin 2 
One cell between veins Al and A2 at their origin 3 
2. Two cells ; if one, elong-ated, the margin not thickened. 
Hind femora of sexes similar ; posterior genital hamule of male 
generally vertical; segment 8 square at apex Gomphus 
Hind femora of sexes different, male hairy, female with many 
stout spines below ; posterior genital hamule of male directed 
posteriorily ; segment 8 oblique at apex Arigomphus 
3. One cell, the border thickened. 
Abdominal segments 7 — 9 dilated ; posterior genital hamule of 
male perpendicular Gomphurus 
Abdominal segments 7 — 9 not dilated ; posterior genital hamule 
of male directed anteriorily Stylurus 
Subgenus GOMPHUS, 
The characters of this group, as indicated by the table, are 
prominent enough to constitute a separate group of species. Sev- 
eral species, three in number, form a class by themselves by the 
presence of only one cell between veins Ai and A2 of the hind 
wing. 
1. Two cells between veins Al and A2 2 
One cell between veins Al and A2 6 
2. Segment 9 longer than, or at least equal to 8 3 
Segment 9 shorter than 8 brevis 
3. Legs with some green or yellow 4 
Legs entirely black quadricolor 
4. Tibiae yellow externally 5 
Tibiae black externally descriptus & borealis 
5. Length about 52 mm sordidus 
Length about 43 mm exilis 
6. Dorsum of 9 & 10 yellow 7 
Dorsum of 9 & 10 black fraternus 
7. Ground color black, markings olive and yellow graslinellus 
Ground color dark brown, markings yellow externus 
Gomphus brevis Hagen, Bull. Ac. Belg. (2) 46:464, 1878; Need- 
ham, Bull, 47 N. Y. State :Nrus., p. 449, 1901, (Bibliography, Description 
of n;yTnph and imago). 
Abd. male and female 31—33 ; h. w. 26 — 27. 
Male. — Black and green. Face banded with black on all sutures, 
upper part of front and occiput olive. Thorax with a short mid-dorsal 
black line, not reaching the prothorax. The humeral and antehumeral 
stripes connected above. Legs entirely black. Abdomen black, yellow 
