1908] 
3IuttJcowski, Dragon Flies of Wisconsin. 
8S 
13. Yellow and dark-brown; superior appendages trigonate, ex- 
ternally truncate ; vulvar lamina very short, the apex ex- 
cised militaris 
Brown and fuscous ; superior appendages trigonate ; vulvar 
lamina oblong, bifid pilipes 
14. Length between 40 and 50 mm 15 
Length over 50 mm 16 
Length imder 40 mm abbreviatus 
15. Abdominal segments 7 — 9 greatly dilated ventricosus 
Abdominal segments 7 — 9 little dilated quadricolor 
16. Dorsum of segment 9 yellow 17 
Dorsum of segment 9 black 18 
17. Segment 7—9 greatly dilated, vulvar lamina constricted at 
base crassus 
Segment 7 — 9 little dilated, vulvar, lamina short, broad, bifid 
olivaceus 
18. Segment 10 and appendages yellow 19 
Segment 10 and appendages black 20 
19. Segment 8 with a yellow basal spot, 10 with a yellow spot 
cornutus 
Segment 8 black, 10 largely yellow furcifer 
20. Segment 7 — 9 not expanded 21 
Segment 7 — 9 greatly expanded fraternus 
21. Superior abdominal appendages acute, outwardly truncated, 
the inferior tooth directed downward ; vulvar lamina bifid 
descriptus 
Superior abdominal appendages less acute, the inferior tooth 
directed far inward; vulvar lam.ina not so deeply bifid, less 
diverging borealis 
22. Yellow stripes on thorax dilated anteriorily , 23 
Yellow stripes on thorax narrow, isolated scudderi 
23. Sides of hind femora black 24 
Sides of hind femora yellow amnicola 
24. One cell between veins Al and A2 at their origin ; length more 
than 45 mm 25 
Two cells between veins Al and A2 at their origin ; length less 
than 45 mm. brevis 
25. Mid-lateral thoracic stripe incomplete; length above 50 mm.. 26 
Mid-lateral thoracic stripe complete ; length less than 50 mm. 
. adelphus 
26. Abdominal segments 8 — 9 with some yellow 27 
Abdominal segments 8 — 9 black dilatatus 
27. Dorsum of 8 with a basal spot j'^ellow; 9 largely black. . . .notatus 
Dorsum of 8 with a basal spot yellow ; 9 largely yellow .... vastus 
28. Ground color brown ; segment 9 about equal to 8 plagiatus 
Ground color black ; segment 9 much longer than 8 spiniceps 
The species of Gomphus can be naturally sub-divided into sev- 
eral groups or sub-genera. Chief distintive characters are the 
presence of one or more cells between veins Ai and A2 of the 
anal angle, the sexual similarity or dissimilarity of the femora, 
the form of the posterior genital hamule of the male, and the 
