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



Abdomen: cuticle provided with numerous small black spots, 

 each bearing a single seta; lateral keels without spines, except 

 those of the segments 4 or 5 to 8 ; gills (PI. 11, Fig. 6) lanceolate, 

 broadest beyond the middle, and usually with 4 crescentic brownish 

 bands, of which the 3 apical ones are paler ; median gill with 

 a dorsal row of about 14 spines extending one-third the length 

 of the gill from the base ; ovipositor extending to the apex of the 

 tenth abdominal segment. 



Measurements : length, 11. 5 mm. ; length of abdomen, 7.5 mm. ; 

 length of gills, 5-5.5 mm.; width of gills, 1.6 mm.; length of 

 median lobes, 2.0 mm.; width of median lobe, .5-1.6 mm. 



Adult, male. — Color black and yellow. 



Head : antennae uniform dark brown ; labrum black on the 

 dorsal border, the black area projecting ventrad a little on the 

 meson ; genae, mandibles, and the front to the antennae yellow ; 

 remainder of the front and vertex black, the postocular spots 

 yellow and almost circular ; postgenae and occiput yellow. 



Thorax : black and yellow ; mesepisterna with short yellow 

 stripes and spots adjacent to the paraptera, the two forming an 

 exclamation point on each side of the dorsal carina ; thorax yellow 

 below ; legs black and yellow, the femora pale with a dorsal black 

 stripe on each from bases to apices, the stripe wddened subapically ; 

 tibiae with a dorsal stripe on each from bases to the apices, 

 the stripes fading into brown at apices ; tarsi and claws pale, 

 darker at tips ; wings with 6 to 8 postnodal cross-veins in the 

 front wing and M^ arising between the third and fourth postnodal 

 veins in the front and between the second and third in the hind. 



Abdomen: black and yellow; terga i-io dull black with excep- 

 tion of a narrow basal ring on segments 3-7, the stripe narrowed 

 on segment 2 at apex and widened on 3-6, lateral margins of the 

 terga pale; apex of the tenth tergum with a mesal elevation, the 

 elevation forming two small tubercles; anal appendages (Fig. 10, 

 No. 12) small, orange in color, the superiors large and blunt, the 

 inferiors bilobed, the superior lobe with small teeth. 



Female. — -Color pale blue and black. 



Head : postocular spots blue. 



Thorax : pale blue and black, sometimes lacking the black 

 stripes on the metapleural sutures ; occiput usually yellow, some- 

 times pardy black ; mesostigmal plates without an elevated ridge. 



Thorax : black and yellow ; pronotum mostly black, the cephalic 

 lobe sometimes partly yellow and the caudal lobe with a pale spot 

 on each lateral angle ; mesepisterna with yellow stripes. and_ spots 

 adjacent to the wing bases, the two together forming a distinct 

 exclamation point on each side; dorsal half of the mesepimera 

 black, the black stripe widened just behind the katepistema ; meta- 

 thorax and the postcoxal areas yellow ; legs black and yellow ; 

 tarsi and claws pale, darker at tips ; wings short. 6-9 postnodals 



