LIST OF DIPTEKA. 223 



Thereva conspicua, n. s., mas. Fusca, capite fulvo subtus cano, 

 thorace fulvo bivittato, pectore cinereo, abdomine rvigro albo tri- 

 maculato, pedibus cinereis, tibiis fulvis, tarsis piceis, alis sub- 

 cinereis. 



Head tawny above, white in front, hoary behind and beneath, 

 where it is clothed with white hairs ; there are a few black bristles 

 behind the eyes which are red : feelers gray : the first joint clothed 

 with black hairs : chest dark brown, with two tawny stripes ; the 

 sides hoary : breast gray : abdomen black, shining, thinly clothed 

 with short black hairs ; there is a large triangular white spot on 

 the hind border of each of the segments from the first to the third ; 

 the first is narrower than the two other spots, and the second is 

 larger than the third, and they are all clothed with white hairs : 

 legs gray ; shanks tawny ; feet piceous ; wings slightly gray ; 

 brands brown ; veins piceous, very slightly bordered with brown ; 

 poisers dark ferruginous, their knobs piceous from the base to the 

 middle, pale yellow thence to the tips. Length of the body 4 lines ; 

 of the wings 8 lines. 



a. Nova Scotia. From Lieut. Redman's collection. 



Thereva nervosa, n. s., mas. Niger, abdomine piceo basi subtus 

 ferrugineo, antennis pedibusque fulvis, femoribus cinereis, alis 

 subcinereis, venis fusco marginatis. 



Head and chest black : head clothed with black hairs above, 

 and more thickly with white hairs beneath : feelers tawny ; first 

 joint very long and thick, and clothed with long black hairs : breast 

 thinly clothed with long white hairs : abdomen piceous, ferruginous 

 beneath towards the base : legs thinly clothed with black bristles and 

 short black hairs ,* hips and thighs gray ; shanks and feet tawny ; 

 tips of the feet-joints piceous : wings slightly gray, especially at the 

 tips and along the fore borders ; brands and veins brown ; cross - 

 veins bordered with the same colour ; poisers tawny, with hrown 

 knobs. Length of the body 4 lines ; of the wings 8 lines. 



a. Georgia. From Mr. Abbot's collection. 



Thereva plagiata, Harris, Cat. Ins. Massachusetts. Cinerea, capite 

 subtus pectoreque albis, abdomine nigro albo trifasciato, basi sub- 

 tusque cano, antennis nigris, pedibus canis, alis cinereis. 



Body gray : head in front and breast white : eyes, feelers, and 

 mouth black : abdomen black, hoaiy at the base and beneath, and 

 having three white bands on the back ; the first and the second are 

 narrow, and traverse the hind borders of the first and second seg- 

 ments ; the third occupies the hind border of the third and nearly 

 the whole of the fourth segment ; tip of the abdomen also white : 

 legs hoary ; hips white : wings gray, with a slight brown tinge along 



