573 



tapering points, the dorsal marginal setae of the median gill usually 

 extending nearly half the length of the gill from the base, the ventral 

 row of the same gill consisting of about seven strong setae, consider- 

 ably farther apart than those of the dorsal row; ventral marginal 

 setae of the lateral gills extending slightly farther from the base of 

 the gills than the dorsal row of the median gill; pigment of the gills in 

 the form of one or two arcuate cross-bands near the middle of the 

 gill; these, however, may be wanting; ovipositor extending to the 

 middle of the tenth abdominal sternum. 



Measurements 



Length 13-14 mm. 



Length of abdomen 9-10 mm. 



Length of gills 6-7 mm. 



Width of gills 1-1.3 mm. 



Length of median lobe 1.8 mm. 



Width of median lobe 6-1.6 mm. 



Adult; Male. — Color, black or dark metallic green and pale green. 



Head black and yellowish green ; mouth-parts buff, the median 

 lobe of the labium subtriangular, the cleft short and acute at the prox- 

 imal end ; antennae black or very dark brown ; postclypeus black, shin- 

 ing; anteclypeus, labrum, exposed portion of the mandibles and 

 their trochantins, genae, and the front above the clypeus, yellow ; 

 postocular spots large and subcircular; vertex, and front except the 

 stripe above the clypeus, dull black ; occiput black and greenish yellow. 



Thorax greenish black and greenish yellow ; pronotum shining 

 black with a transverse yellow stripe on the cephalic lobe ; caudal lobe 

 of the pronotum with a distinct transverse carina; noto-epimeral suture 

 indistinct, the proepimera and episterna largely yellow; mesothorax 

 shining black with a yellow stripe just above the mesopleural suture; 

 ventral half and cephalic shoulder of the mesepimera yellow ; paraptera 

 trapezoidal, with a yellow spot just ventrad of the lateral angles, the 

 remainder black ; mesostigmal plates black, the caudal margins ele- 

 vated and lined with yellow ; metathorax including the postcoxal areas, 

 pale green or yellowish; legs black and yellow, the coxae and tro- 

 chanters pale with some darker marks on the sutures; femora all with 

 a broad dorsal stripe, the tibiae with narrower dorsal stripes extending 

 from near the bases to near the apices ; tarsi and claws pale, dark at 

 the tips; wings short, the postnodal cross-veins seven to nine, and M 2 

 arising between the third and fourth postnodal cross-veins in the front 

 wing and between the second and third in the hind wing. 



