On the Biaconidpc in the British Museum. 163 



XVTI. — yotes on the B;aconi(l?e in the British Museum. — 

 IV. On new \i^\com\\di, mostly Australian. Bj ROWLAND 

 E. Turner, F.Z.S., F.E.S. 



Key to the Australian Geneva of Helcouiuce. 



1. Recurrent nervure received by second cubital 



cell Megalohelcon, gen. n. 



Recurrent nervure received by first cubital 

 cell 2. 



2. Median lobe of mesonotum depressed below 



the lateral lobes Paraheleon, Kokuj. 



Median lobe of mesonotam not depressed . , 3. 



3. Anal cell of fore wing with two fully deve- 



loped transverse nervui'es ; first tergite 

 large, constricted at one-third from the 

 base, the basal poi'tion bUobed and mas- 

 sively subtuberculate on each side of the 



anterior margin Calokelcon, gen. n. 



Anal cell of fore wing with one transversa 

 nervure, rarely with indications of the 

 second ; first tergite not abnormal 4. 



4. Frontal excavation present 5. 



Frontal excavation absent Aspidocolpus, Wesm. 



5. Anal cell of fore wing with indications of a 



second transverse nervure Gymnoscelua, Forst. 



Anal cell of fore wing without any indication 

 of a second transverse nervure 6. 



6. Median segment and two basal tergites clothed 



with dense grey pubescence ; second ter- 

 gite with a median longitudinal carina . . Trichiohelcon, gen. n. 

 Median segment and abdomen without dense 

 pubescence ; second tergite without a 

 carina Austrohelcon, gen. n. 



Typical Gymnoscelus lias the second transverse vein of the 

 aual cell fully developed. 



Megalohelcon, gen. nov. 



Mandibles bidentate at the apex, the inner tooth much 

 longer than the outer j anterior margin of the clypeus straight. 

 Face produced into a spine above the base of the clypeus, 

 with a curved carina on each side near the inner margin of 

 the eyes ; cheeks as long as the third joint of the flagellum. 

 Head large, transverse, as broad as the thorax ; eyes broadly 

 oval, ocelli very large ; frontal depression not well defined. 

 Antennae about 77-jointed. Median lobe of the mesonotum 



