340 PROCEBDl^UH OF THE \AT10XAL MVtiEUM. vol.4!). 



up as does the female of ArcMlestes and was placing eggs in a small 

 willow stem about 2 inches above the surface of the water. In view 

 of the abundance of congener, the lack of other species on the creek, 

 and the careful collecting done, together with the small size of con- 

 gener, with which the single skin agrees, I feel sure that this is the 

 nymphal skin of congener. 



Length (head, thorax, and abdomen), 17 mm.; gills, 7 extra; 

 abdomen, 12; hind femur, 4.5. 



The nymph (figs. 168 and 169) is long and slender, but not so 

 slender as the nymphs of rectangularis and others of the larger spe- 

 cies of Lestes. 



Head two and one-half times as \vide as long (this measurement 

 may be at fault because of the distortion of the skin) . Eyes occupy- 

 ing only half of total width of head. Notch at back of head wide and 

 shallow. Antennae (see fig. 171) with segments 1 and 2 heavy, the 

 second longer than the first, the tliird to the seventh slender. The 

 segments increase in length to the third and decrease to the seventh, 

 which is minute. Labium (fig. 170) slender, but the base of the 

 mentum not so slender as in L. rectangularis. Closed median cleft of 

 median lobe extending below bases of lateral lobes. Mental setae 

 long, a row of seven on either side. A seta on base of each lateral 

 lobe and four large setae on each movable hook. Each lateral lobe 

 bears three large hooks, the inner of which is the largest and having 

 on its inner edge a row of minute teeth ; the outer hook is second in 

 size. Next the outer side of the middle tooth is a cutting edge of six 

 or seven minute teeth. 



Prothorax conic, with the dorsal scutum rectangular. Legs with 

 faint band on distal end of femur. 



Abdomen cylindric. Lateral keels of segments 5-9 terminating 

 caudad in a sharp point. (See fig. 172.) Abdomen with lateral white 

 stripe above each lateral carina and a middorsal white stripe. The 

 dorsum of each abdominal segment with four black spots on its distal 

 margin, one above posterior end of each lateral keel, and one on either 

 side of the middorsal white spot. Gills (see fig. 168) oblong-lanceo- 

 late, with two dark spots on each edge. 



4. LESTES DISJUNCTUS Selys. 



I find several specimens of this from a slough near T(-)pi)cnish. 



5. LESTES UNCATUS Kirby. 



Common about the various ponds. The specimens are not so 

 brilliant as those from Bend, Oregon. 



6. LESTES UNGUICULATUS Hagen. 



Found occasionally about alkahne ponds. 



7. ARGIA EMMA Kennedy. 



Common along the streams from the last week iu June until 

 September. It is most abundant on Satus Creek soutli of Alfalfa. 



