, Dolichopodidae. 21 



the base, then excised below and with the apical part 



thin 16. Machaerium. 



— Third antennal joint long in the male, shorter in the 

 female, not excised below 3. 



3. Hind metatarsus considerably shorter than, about half 

 as long as the second joint; hypopygium in the male 

 free, pedunculated 18. Systenus. 



— Hind metatarsus from slightly longer to somewhat shorter 

 than the second joint ; hypopygium in the male more 



or less imbedded, not free 4. 



i. Hind coxæ without bristles on the outside; third an- 

 tennal joint in the male moderately long, not more 

 than thrice as long as high, larger, hairier species.. 14. Porphyrops. 



— Hind coxæ with a bristle on the outside ; third antennal 

 joint in the male more elongate, six to ten times as 



long as high; smaller, less hairy species 17. Xiphandrium. 



IV. Hydrophorinae. 



Arista dorsal, siibapical or apical; the second antennal joint simple, 

 rarely overlapping the third a little, the third short, or sometimes a 

 little elongated. Postocular bristles forming a single row, sometimes 

 with bristles inwards to it, or the lower part of occiput covered 

 with dense hairs. Acrostichal bristles present or absent, in the former 

 case uniserial, sometimes a little biserial behind; only in Achalcus, 

 Thrijpticus and Medeterus biserial. Propleura without, or with one to 

 several prothoracic bristles; hind coxæ likewise with or without 

 bristles on the outside. Hypopygium generally small and imbedded, 

 in Thrypticus and Medeterus free; the outer lamellæ generally small 

 or somewhat small, often united in the middle. Anal vein generally 

 present, sometimes wanting {Achalcus, Thrypticus). — This subfamily 

 is no doubt heterogenous, and should be subdivided; thus f. inst. 

 Medeterus and Thrypticus seem to form a natural group. Aldrich 

 has divided it into Synipycninae, Xanthochlorinae, Tinophilinae, Mede- 

 terinae, Hydrophorinae and Aphrosylinae, after having excluded Camp- 

 sicnemus and Teucophorus, which are placed in the Diaphorinae. 



Tahle of Genera. 



1. Acrostichal bristles present 2. 



— Acrostichal bristles absent (or practically so) 11. 



2. Acrostichal bristles biserial 3. 



— Acrostichal bristles uniserial (at most a little ir- 

 regularly biserial behind) 5. 



3. Anal vein present; hypopygflim in the male large, 

 pedunculated 21, Medetems. 



— Anal vein absent 4, 



