60 



The nymph measures 24 mm.; the abdomen, 14 mm.; the 

 hind femur, 4 mm.; width of head 5 mm., of abdomen 7.5 mm. 



Body sparsely covered with clavate hairs and minutely 

 pointed blackish granulations; 3d joint of antennae very flat, 

 oval. Labium short, meeting in front a posteriorly directed 

 fringe of hairs growing under the edge of the labrum. Lateral 

 spines on 7 to 9, those of 9 half as long as segment 10 at mid- 

 dle. Dorsal hooks on 3-9, very low and broad with decurved 

 apices. Lateral abdominal appendages al:)out three fifths as 

 long as the subequal superior and inferiors. 



3. Difisf((fo)}nn<i sp. {a). 



Nymphs taken by Mr. Hart from gravelly shallows of the 

 Ohio River at Golconda, in southern Illinois, October 27, differ 

 from those of carol us in having lateral spines on the 6th 

 segment of the abdomen. 



The nymph measures 25 mm.; abdomen, 15.5 mm.; hind 

 femur, 4 mm.; width of abdomen 8 mm., of head 5.2 mm. Color 

 (in alcohol) yellowish with black points at top of thoracic 

 sutures and a pair each side of each dorsal hook ; scars lirown- 

 ish. Body moderately hairy, lateral spines on abdominal seg- 

 ments 6 to 9. Dorsal hooks on 2 to 9, large and subcultriform 

 in front, regularly decreasing to a rudiment on 9 ; superior and 

 inferior abdominal appendages long, laterals very little shorter. 



V. Hagenius Selys. 



There is Init one North American species of this interest- 

 ing genus, the flat nymph of which is conspicuously unlike that 

 of any other dragon-fly in form, as described below. It is found 

 clinging to the flat surfaces of driftwood and stones or amongst 

 dead leaves. The Epliciiwi-ida' inhabiting such surfaces are also 

 conspicuously flattened. They are therefore not easily picked 

 off by fish nor dislodged by a rush of water, and are able to slip 

 away through narrow crevices. Perhaps Hagenius has this 

 shape for similar reasons. Its blackish color is evidently pro- 

 tective. 



