138 DRAGONFLIES OF NORTH AMERICA 
14 Vein M1/a rising under the proximal third of the stigma or before 
ita’ inner end). 4))s)32 4... 14 ee eA ae eremita, p. 146 
Vein M1/a rising under the middle or distal third of stigma... .15. 
15 Sides of lateral thoracic pale stripes more or less straight; first 
one without dorsal posterior spur.............. juncea, p. 147 
Sides of lateral thoracic pale stripes excavated; with a dorsal 
posterior spur on first stripe... ..4).45.+ tee subarctica, p. 148 
16 Abdominal segment 10 black.............. tuberculifera, p. 148 
Abdominal segment 10 with pale spots..................... ii. 
17 Anterior margin of first lateral thoracic pale stripe rectangularly 
BEREIRHO Ret, 3) Mie. <a ile yiellhG tt a Pee ree canadensis, p. 148 
Anterior margin of first lateral thoracic pale stripe obtuse- 
angularly sintate ad) lh ORL pa ow eee verticalis, p. 149 
+ In the determination of species the final criteria must be the genitalia 
Characters such as the color of the face and the dark markings on it, and even 
the thoracic color pattern, are dependent too much upon state of preservation of 
the specimen to be reliable; the dorsal thoracic pale stripes are often too faded 
to be discernible. For a careful and detailed description see Dr. Walker’s mono- 
graph: The North American Dragonflies of the genus Aeshna, University of 
Toronto Studies, Biological Series No. 11, 1912. This very excellent work is 
indispensable to any worker in the genus. It has been drawn upon to a very large 
extent in assembling the material herein. 
* Not constant; see figures of genitalia. 
Nymphs 
1 End hook of labium curving to an internal terminal tooth..... 2. 
find of labium trunmeste.3. si. oo5 2s ea eee 4. 
2. End hook broadly curved toa points 2914. ee ee ee 3. 
End hook abruptly curved, almost truncate......... canadensis. 
3 End of lateral lobe slender, 9 X 1.5; lateral spine on 6 less than one 
fourth‘as long as segments! 2.005 eos ee ee constricta. 
End of lateral lobe broader, 7X3; lateral spine on 6 one half as 
long as the: segmentin 3: Stee eer cee. Sees. clepsydra. 
4‘, Eaters! spimes.on 5-9). scene he ee sek ko: a oe 5. 
Lateral. spines. on..6-9..)) so4a5 68 A a eee 6. 
5 Lateral spine on 9 reaching beyond the posterior margin of 10.. 
SOLS, SPL Ae PRR RE SS eh ee ee interrupta. 
Lateral spine on 9 reaching three fifths of the margin of 10 (all 
spines shorter than in the above).................-. eremita. 
6: ‘Femora ‘coneolorous: =) .0,. JPRS a ee peer eis ese ff 
Femora striped « 3 gf es oS Da Eee tener nota 8. 
