486 



much more pigment than the sterna, and with small setae distributed 

 evenly over the surfaces ; sternum of segment ten with long hair-like 

 setae; gills (Fig. 49) spatulate, broadest just proximad of the middle, 

 three or four times as long as broad; tips rounded or obtusely pointed, 

 black, and two rather indistinct dark cross-bands proximad of the tip; 

 gills sometimes nearly black. 



Measurements 



Length 19-20 mm. 



Length of abdomen 14 mm. 



Length of gills 8.5-9 mm. 



Width of gills 2-3 mm. 



Length of median lobe 2.4 mm. 



Width of median lobe 5-1.7 mm. 



Adult; Male. — Color, dark brown and yellow\ 



Head brown and buff, the median lobe of the labium pale or 

 nearly white, subquadrangular in outline, the median cleft shallow 

 and narrow but apparently extending well towards the base of the 

 piece ; proximal segment of the palpus pale, except the distal half of the 

 fixed hook which is black; antennae dark brown with a short basal 

 segment, a much longer second segment, and two terminal aristiform 

 segments which together are much longer than the two basal ones; 

 clypeus and labrum pale yellow or greenish ; exposed portions of the 

 mandibles, their trochantins, and the genae as far dorsad as the f ronto- 

 clypeal suture, pale ; front and vertex brown ; occipital and postgenal 

 regions largely dark brown or black, becoming pollinose with age. 



Thorax brown and yellow; prothorax brown above, pale below, 

 the proepimera distinct, pale, with a dark dorsal border; caudal lobe 

 of the notum not especially prominent or convex, the cephalic lobe 

 with a median circular black spot and the median lobes each with an 

 irregular H-shaped dark mark; cephalic portion of the prescutum tri- 

 angular, not deeply depressed ; stigmal plates brown and black ; pleural 

 sutures and the dorsal carina pale, the pale stripe of the mesopleural 

 suture becoming bluish with age ; legs striped, yellow and black, the 

 coxae and trochanters entirely pale, the femora and tibiae striped and 

 the tarsi and claws entirely black ; wings with ten to eleven postnodal 

 cross-veins and with M2 arising between the third and fourth post- 

 nodals in the front wing and between the second and third in the hind 

 wing. 



Abdomen dark brown, often with a trace of metallic green; 

 sterna of segments three to nine black; dorsum of terga i-io with 



