64 



Cincinnati Society of Natural History. 



half their moults. The former will be described and figured, 

 and the latter compared as far as may appear necessary for 

 clearness. The seven-jointed antennae, the three-jointed tarsi, 

 the smooth, opposing edges of the lateral lobes of the labium, 

 and the relatively short abdomen place this nymph, without 

 question, among those of the Family Libellulidae. 



The size is as follows: Total length, 15 mm.; of the abdo- 

 men, 7 mm. ; width of abdomen, 6.5 mm. ; of the head, 5 mm. ; 

 length of wing covers 7 mm. ; of the extended labium, 7 mm. 

 The general color is slightly olivaceous above, more or less 

 mottled ; beneath whitish. 



The head, seen from above, is subquadrangular ; vertex and 

 posterior lateral angles rounded ; frons concave between the 

 rather small, round eyes, and slightly convex at the union 

 with the clypeus ; labium whitish ; the opposing edges of the 

 lateral lobes smooth-bearing, chestnut setae ; antennae pale; 

 joints 3, 6, and 7 are nearly equal, and as long as 1 and 2 to- 

 gether ; 4 and 5 are shorter ; the covered-mouth parts are 

 villous. 



The front of the prothorax is vertical, and fcas a sulcus par- 

 allel to its upper margin ; the latter is quite deeply bilobed. 

 The legs are obscurely ringed, with darker shades. 



The lateral margins of the abdomen are strongly produced ; 

 there are no dorsal hooks or lateral marginal spines ; the tenth 

 ring is very short, 3 to 9 longer and equal. The abdominal 

 appendages are about the length of 9 and 10; the superior 

 middle one is shorter than the lower laterals, broad at base, 



