286 TttE CANADIAN ENTOMOLOGlST. 



Hind tibiae and tarsi somevvhat thickened, the former 



with a longitudinal sulcus Holcocnema, Konow. 



Hind tibiae and tarsi normal Nematus, Jurine. 



First dorsal abdominal segment with a deep median incision ; 

 terminal ventral plate more than twice as long as wide ; 



frontal area wanting Amauronematus, Konow. 



10. Hind femora and tibice somevvhat thickened, the tarsi 



normal Hypolaepus, Kirby. 



Hind tibife towards apex and first joint of liie tarsi strongly com- 

 pressed and very broad Croesus, Leach. 



Family XHI.— Dineurid.b. 

 This group has heretofore baen classified with the Nematidce, but 

 from which it is readily separated by having two marginal cells in the front 

 wings. It appears to me, however, to be more closely allied to the 

 Selandriidce, and especially to the Tefit/iredijiidce, than to the Nematida, 

 and probably was evolved from the latter. The basal nervure uniting 

 with the subcostal vein some distance from the origin of the cubitus sepa- 

 rates it from the former, while the short oviform abdomen and the vena- 

 tion of the front wings distinguish it from the latter. 



Two subfamilies have been recognized, separated as follows : 



Table of Subfamilies. 

 Lanceolate cell contracted near the middle, closed at 



base Subfamily L, Hemichroinae. 



Lanceolate cell petiolate Subfamily H., Dineurinae. 



Subfamily L — Hemichroin.^^. 

 This subfamily in having the lanceolate cell contracted at or near 

 the middle, and in the habitus of the species, closely resembles the Hoplo- 

 i:aw/z«« in the family Selandriidge, and suggests the possibility of its 

 being the phylum from whence that family originated. 



The genera may be recognized with the aid of the following table : 



Table of Genera. 

 Costal transverse nervure not interstitial, placed much before the apex of 

 the basal nervure ; third submarginal cell more than twice as long as 

 the first ; claws bifid. 



Second submarginal cell receiving both recurrent nervures, or the 

 second recurrent is interstitial ; first recurrent nervure in hind 

 wings 7iot twice the length of the first transverse cubitus, the anal 

 cell longly petiolated Hemichroa, Curtis. 



