490 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



A quarter of a mile below Sears ville dam many pairs were caught 

 about a pool shaded by large alders and in the open glades in the 

 underbrush males were abundant. 



During May I found a few individuals about a deep pool in Coyote 

 Ci-eek at San Jose, California. On June 11, 1914, 1 caught this species 

 on the Sacramento River at Colusa, California, and on June 14, on the 

 Chico River at Chico, Cahfomia. On July 9 it was common in the 

 willows along the San Lorenzo River near Santa CiTiz, California. 

 This was the last date on which it was seen. Thus the season extends 

 from April to July. 



Measurements: Length of abdomen: Male, 26-27 mm.; female, 

 20-22. Length of liindmng: Male, 20 mm.; female, 20-22. 



Male, structural notes. — Head wide, its extreme width tmce its 

 length. Antennal and fronto-vertical fossae well developed. Occipi- 

 tal ridge low. Prothorax with middle lobe divided along mid- 

 dorsal hne from front to center into two low, smoothly rounded 

 halves (figs. 28-29). Posterior lobe thin, as much higher than the 

 middle lobe as that is than the anterior lobe, erect (almost vertical), 

 shghtly emarginate on the posterior edge. Just ventrad of the lateral 

 terminations of the posterior lobe the side of the prothorax is bulged 

 into a conspicuous swelhng. 



Front femur with 4 internal and 6 external spines, middle with 9 

 internal and 8-10 external spines, hind with 8-9 internal and 8-9 

 external spines. Front tibia with 3 internal spines and 9 external, 

 middle with 13 internal and 7-8 external, hind ■\\'ith 18 internal and 

 10 external spines. Hind femur reaching to middle of segment 2. 

 Wings reaching to apical fourth of segment 6. 



Pterostigmas equilateral, rhomboidal (almost square). A large 

 hemispherical tubercle on ventrum of metathorax with a pair of con- 

 spicuous black spots on its anterior surface. 



Posterior hamules low, rounded, not reaching the ventral edge of 

 the genital fossa. A minute spine on inferior, anterior angle of side 

 of segment 3. Abdomen slender. Segment 10 with a middorsal, 

 apical, forked projection, which projects httle above the middorsal 

 contour. Inferior appendages %vith two branches, a flat branch 

 extending dorsad and mesad and closely apphed to the posterior end 

 of 10 and a slender ventro-extemal branch as long as 10, this tapering 

 regularly to its incurved slightly hooked tip. The dorsal appendages 

 are thin and laminalike and curve abruptly mesad and ventrad, each 

 terminating ventrally in a small point lying on the inner side of the 

 base of the external branch of the respective inferior appendage. 

 (See figs. 25-27.) 



Female, structural notes. — Structure as in male except in the geni- 

 talia. Segment 10 one-haK length of 9. Appendages three-fifths 

 length of 10, broad with romided tip. Segment 8 with a large flat 



