74 CONNECTICUT GEOL. AND NAT. HIST. SURVEY [Bull. 



gills from their bases, and usually less than 20 spines on dorsal 

 margin of the median gill. 



Measurements : length, 11-12 mm. ; length of abdomen, 9 mm. ; 

 length of gills, 4.7 mm. ; width of gills, 1.3 mm. ; length of meta- 

 thoracic wing-cases, 2 mm. ; length of median lobe of labium, 2 ; 

 width, .6-1.5 ^^• 



Adult, male. — Color pale blue, black and buff. 



Head : blue and black, mouth-parts buff, with a tinge of blue in 

 fresh specimens ; antennae dark brown or black, the tips of the 

 first and second segments sometimes pale; postclypeus shining 

 black, except the lateral angles which are blue; anteclypeus and 

 labrum blue, the labrum with a dorso-mesal black spot; frontal 

 area above the clypeus to the level of the antennae blue, remainder 

 of the front black ; postocular spots large, blue, rather irregular, 

 and frequently with serrated margins ; pale stripe caudad of ocelli 

 wanting; occiput and postgenae mostly buff, compound eyes 

 brown above, pale below. 



Thorax : blue and black, buff below ; pronotum black, the 

 cephalic and caudal lobes mostly blue, median lobes black; pro- 

 epimera largely blue, mesostigmal plates, with blue lateral angles 

 and caudal margins ; mesothorax with the dorsal black stripe 

 covering half or one-third of each anepisternum, the blue stripe 

 of that sclerite contracted at the caudal third or fourth, and occa- 

 sionally interrupted, forming an exclamation point; black stripe 

 of the mesopleural suture widest adjacent to the katepi sternum, 

 and covering the dorsal half of that sclerite; metapleural suture 

 black ; ventral half of the mesepimera, and the metapleura blue ; 

 postcoxal areas pale or buff; legs striped, black and blue or buff; 

 tarsi and claws black, pale in tenerals; wings with 7-10 postnodal 

 cross-veins in the front wing, and M^ arising between the fourth 

 and fifth of these. 



Abdomen: blue, buff, and black; tergum i, blue with a black 

 basal spot ; second tergum blue with black dorsal spot, apical ring 

 and lateral stripe on each side near the margin ; terga 3-7 with 

 longitudinal black stripes on the dorsum from the bases to the 

 apices, the stripes widened subapically, connected with the apical 

 rings which reach the lateral margins of the sclerites ; dorsum 

 of 10, narrowed lateral margins of 8 and 9, black or dark brown ; 

 dorsum of 8 and 9 blue ; basal rings, usually interrupted on the 

 meson in 5-7, pale yellow or blue. Anal appendages (Fig. 10, 

 Nos. 3, 7) black and buff, the superiors black with paler tips, 

 inferiors slightly longer than the superiors, yellowish, with the 

 black tips directed mesad. 



Female. — Color similar to the male. 



Head: dorsal half of labrum usually brown. 



Thorax: mesostigmal plates as in Fig. 11, No. 13. 



Abdomen: with broader black stripes on 2-7; terga 9 and 10 



