560 



gills with ten to twelve black cuticular spots on the margins and a 

 distinct arcuate cross-band just beyond the middle ; tracheal branches 

 much more numerous bcNond the middle of the gill; marginal setae 

 large and widely separated, the ventral row of the lateral gills ex- 

 tending about half the length of the gill from the base and the distal 

 setae much farther apart than the proximal ; ovipositor usually ex- 

 tending beyond the apex of the tenth segment. 



Measurements 



Length 10-11 mm. 



Length of abdomen 8 mm. 



Length of gills 4-4.5 mm. 



Width of gills 1 mm. 



Length of median lobe 1.5-1.7 mm. 



Width of median lobe 1.25 mm. 



Described from three specimens obtained from Dr. E. ]\I. Walker, 

 and labeled Toronto, Ont., May 31, 1913. 



Adult; Male. — Color, metallic green and pale blue. 



Head metallic green above, buff below ; median lobe buff, the cleft 

 large and rounded at the base; distal segments of the labial palpi dark 

 at the tips ; antennae black, the second segment with a pale ring at 

 the niidclle; postclypeus shining black, tlie anteclypeus buff; labrum 

 pale yellow with a dorsal, transverse, shining black stripe about one- 

 third the width of the piece ; exposed portions of the mandibles, the 

 trochantins, genae. and the front from the fronto-clypeal suture dorsad 

 to the antennal fossae, shining yellow ; remainder of the front, vertex, 

 and a large portion of the occiput, metallic green; postgenae black, 

 with a pale stripe beneath the compound eyes which is continuous with 

 the yellow of the genae ; compound eyes brown. 



Thorax metallic green and pale blue ; pronotum metallic green 

 without paler spots, the margin of the caudal lobe entire ; proepimera 

 buff-colored ; dorsal carina and the mesoplcural suture lined with 

 I)lack; mesosupraepisterna and tlie mesepimera except the cephalo-ven- 

 tral shoulders metallic green ; dorsal margin and about the ventral half 

 of the mesinfraepisterna pale, the remainder metallic green ; remainder 

 of the mesopleura and metaplcura except a green triangle adjacent 

 to the wing base on the metepimera, buff or jjale blue; postcoxal 

 I'.reas buff or pale blue ; legs pale, striped with black ; coxae and tro- 

 chanters pale, all the femora with dorsal stripes extending from the 

 apices nearly to the bases, antl the front femora with a short cephalo- 



