168 THE CANADIAN ENTOMOLOGIST, 



2. One third or more of the length of the abdomen, formed by the 



loth abdominal segment (supposition). Aphylla, 



Tenth abdominal segments not longer than the other segments.. j. 



3. Middle legs less distant at base than fore legs Progoinphus. 



Middle legs not less distant at base than fore legs (These 



apparently not separable) Herpetogotnphus and Ophiogotnp/ius. 



4. Third joint of antennae flat, circular 5. 



Third joint of antennse cylindric, at least twice as long as wide. .6. 



5. Abdomen flat, subcircular Hagenius. 



Abdomen ovate, twice as long as wide Lanthus. 



6. Abdominal appendages longer than the loth segment, front bor- 



der of median lobe of labium straight (or in Gomphus occa- 

 sionally very slightly rounded), with the usual fringe of flat 

 scales, but without teeth. Abdomen not abruptly narrowed be- 

 fore 9th segment 7. 



Abdominal appendages shorter than the loth segment; front 

 border of median labial lobe produced into a prominent rounded 

 lobe which is generally armed with a conic apical tooth. 

 Abdomen rather abruptly narrowed to the base of its gih 

 segment, more slowly tapering to the apex Orcus. 



Body spindle-shaped, little flattened ; fore and middle tibi^ with 

 small external apical hooks or with none Stylurus. 



Ninth abdominal segment one half longer than the 8th, its lateral 

 margins nearly parallel. A minute middorsal apical spine on 

 the 9th segment only. Lateral lobe of the labium with a 

 strongly incurved end hook and teeth on the inner margin 

 increasing in size posteriorly. 



Body flat, lanceolate ; fore and middle tibiae with strong external 

 apical burrowing hooks. Ninth abdominal segment hardly longer 

 than the 8th, much narrowed posteriorly. Rudimentary dorsal 



hooks on some of the segments before the 9th Gomphus. 



(To be continued.) 



