254 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



89. Face finely shagreened, alutaceous or coriaceous; propodeum 



exareolated; cubitodiscoidal vein angularly broken and 

 usually with a ramellus; nervellus very obtuse, angularly 



broken below middle Syrphoctonus p. 302 



Face smooth and shining; antennae more than 20-jointed; 

 clypeus separated from face by a suture; propodeum areo- 

 lated; nervellus broken at or near middle .... Promethes p. 302 



90. Scape elongated 91 



Scape globular 92 



91. Areolet present, outer vein of areolet often translucent; trans- 



facial line not much longer than facial line; notauli want- 

 ing; nearly all flagellar joints in female longer than thick; 

 second dorsal abdominal segment without transverse im- 

 pressions Orthocentrus p. 305 



Areolet wanting; epomia wanting 'on sternum; propodeum 

 with basal area and areola confluent. .. . Brephoctonus p. 305 



92. Abdomen petiolate, in some species broadly so, spiracles of 



first dorsal abdominal segment situated in or behind mid- 

 dle 93 



Abdomen sessile or nearly so, spiracles of first dorsal abdom- 

 inal segment situated in or before middle, basal segment 

 broad and short; propodeum usually areolated at base.... 94 

 93. Hind tibiae with a single small spur Periope p. 308 



Hind tibiae with two spurs; areolet wanting; second joint of 

 male antennae excavated Alcocerus p. 308 



94. Second dorsal abdominal segment without a median carina. . 95 

 Second dorsal abdomiaal segment with a median carina .... 



Chorineus p. 308 



95. First joint of flagel decidedly longer than second.. 06 



First joint of flagel not or scarcely longer than second; pro- 

 podeum with six areas Hyperacmus p. 305 



96. Pleural areae of propodeum usually separated from each other 



by a sharp transverse carina 97 



Pleural areas of propodeum not separated from each other 

 by a transverse carina; areolet present Triclistus p. 307 



97. Vertex separated from occiput by a sharp ridge 



Metacoelus p. 307 

 Vertex and occiput without a sharp ridge between them; pro- 

 podeum with two median carinas Exochus p. 306 



98. Face with a distinct shield; mid tibiae with two spurs; basal 



segments of abdomen pyramidal or oval above; ovipositor 



rarely visible Metopius p. 309 



Face without a distinct shield; mid tibiae with a single 

 spur; eyes distinctly emarginate; first, second, and third 

 dorsal abdominal segments with parallel carinas; scutel 

 margined Pseudometopius p. 308 



