THE CANADIAN ENTOMOLOGIST. 1U7 



following segments smooth ; head with a concave depression above 

 each antenna that extends to the vertex ; pygidium strongly com- 

 pressed at the middle, and then broadened into an oval plate, the 

 basal portion, which is separated from the oval apical portion by 

 the strongly compressed portion, is transversely striated, while the 

 apical portion is smooth Zaspilothynnus, Ashni. 



Second abdominal segment with about 13 or 14 transverse carin?e, the 

 first segment with many oblique strise at the sides towards apex, the 

 following segments after the second shining but microscopically 

 shagreened, with a few scattered feeble punctures, especially notice- 

 able on apex of the two last segments ; pygidium compressed 

 basally, dilated apically, but with an emargination on each side at 

 apex, smooth and without transverse striae at 

 base Tachynomyia, Guerin. 



45. Clypeus without a median ridge 46. 



Clypeus tvith a median ridge. 



Pygidium not very narrow, deflexed apically, longitudinally 

 striated, and with a tooth or lobe at each side towards the 

 base ; mandibles broad and flat, obtuse at apex, with a longi- 

 tudinal grooved line along the inner margin and another along 

 the outer margin for a little more than half 



their length Myrmecodes Latreille. 



(Type Tiphia pedestris, Fabr.) 



46. Head without convex impressions extending from the antennas to ver- 



tex, SLibopaque; clypeus transversely narrowed, with a slight median 

 tooth anteriorly ; mandibles long, falcate ; second dorsal abdominal 

 segment with a transverse carina near base and another near apex, 

 the intermediate space multistriated transversely; pygidium oblong- 

 oval, longitudinally striated with a notch on each side before apex ; 

 maxillary palpi 3 -jointed ; labial palpi 

 4-jointed Hemithynnus, Ashmead. 



Head with two convex impressions extending from the antennae to 

 the apex ; clypeus transversely narrowed, with a slight median 

 sinus anteriorly ; mandibles, falcate, acute ; pygidium strongly com- 

 pressed at sides just before the apex, then dilated, and as seen from 

 behind appearing as an oval elevation more or less transversely 

 aciculated, rarely smooth . Agriomyia, Guerin. 



