86 [MarcL, 



legs are also provided with numerous spines, which are arranged in 

 different manners. The wings have the first posterior cell more or 

 less closely contracted and sometimes closed at the end, where it joins 

 the costa, by the apical cross vein, which is formed by the bending 

 upwards of the fourth longitudinal vein. 



It is chiefly by variation in the above characters that the genera 

 and species are distinguished from each other ; and the formation of 

 genera has been found so diiEcult, owing to the impossibility of de- 

 ciding between generic and specific characters, that some authors have 

 given up generic division of the Family altogether. This, however, 

 has been found so inconvenient, that some artificial arrangement, with 

 the adoption of generic names, is absolutely necessary. I have, 

 therefore, drawn up an analytical table of genera, taking the charac- 

 tei'S from Macquart, Schiner, Rondani, and others, which I will insert 

 before commencing the diagnosis of species. 



TABLE OF GENERA. 



1 (70) First posterior wing cell open at the end.* 



2 (23) Arista with the second joint elongated. 



3 (12) Arista straight ; the second joint much shorter than the third. 



1 (11) Antennae with the second joint elongated. 



5 (6) Antennae with the second joint longer than the third .. 



1. EcHiNOMTiA, Dinner. 



8 (5) Antennce with the second joint shorter than the third. 



7 (8) Palpi rudimentary 2. MiCEOPALPUS, Mcq. 



8 (7) Palpi normal. 



It (10) Proboscis Tery long, straight, and slender 3. Aphria, Dsv. 



10 (9) Proboscis rather long, but thick ; fronto-orbital bristles in a double row 



in both sexes 4- Demoticus, Mcq. 



11 (-i) Antenna; with the second joint short. 



12 (3) Arista geniculated ; the second joint nearly or quite as long as the third. 



13 (16) Head wide and swollen. 



14 (15) Cheeks tumid, facial angle nearly straight 5. Gonia, Mgn. 



15 (14) Cheeks not tumid, facial angle inclined backwards... 6. Germaria, Dst. 



16 (13) Head neither wide nor swollen. 



17 (18) Proboscis long, slender, and twice elbowed 7. SiPHONA, Mgn. 



18 (17) Proboscis of the ordinary shape. 



19 Wing-veins setigerous. 



20 (21) Fourth longitudinal vein bent in a curve to form the apical cross vein ; 



abdominal segments without discal eeta 8. Thryptoceba, Mcq. 



21 (20) Fourth longitudinal vein bent at an angle; abdominal segments with 



discal setffi 9. Bigonichkta, End. 



* In some genera the aperture in certain species is very small, or even quite closed. 



