84 Orthorrhapha brachycera. 



balloon attracts the females, and then copulation takes place; when 

 tilis is finished the balloon is dropped. The authors declare, that 

 during the copulation the female sits on the male and the latter 

 holds the balloon and roUs it during the copulation. In accordance 

 with the facts recorded above it seems more probable, that the male 

 hånds the balloon to the female, and that this latter is belovv and 

 holds the balloon during the copulation. 



The genus comprises about 220 species from the palæarctic region ; 

 29 have hitherto been found in Denmark. 



The genus Empis comprises species many of which may differ to 

 no slight degree and show many deviating characters; it might there- 

 fore be thought easy to divide up the genus; yet this is not so 

 on account of intermediate forms, as has already been pointed out 

 by Loew (Wien. entom. Monatschr. VIII, 1864, 353—54) and has 

 since often been repeated. Loew, therefore, contented himself with 

 dividing the genus in his well known groups (Verwandtschaftskreise). 

 In 1909 (Deutsch. ent. Zeitschr. 1909, Beiheft, 85) Bezzi has created 

 a number of subgenera somewhat different from Loew's groups, and 

 I make use here of these subgenera, as I take them to indicate 

 natural groups. Yet I think it will be difficult to get a sharp distinc- 

 tion between two of them, viz. Empis and Pter empis. 



Tahle of Suhgenera. 



1. Dorsocentral bristles uniserial, acrostichal bristles 

 absent 2. 



— Dorsocentral bristles bi- or pluriserial (only in E. 

 livida uniserial, but this species is known by the 

 abbreviated branches of the discai vein) 3. 



2. More or less yellow species; the head long, pear- 



shaped ; hind femora not thickened I. Xanthempis. 



— Not yellow species ; head round ; hind femora thickened II. Anacrostichus. 



3. Eyes in the male broadly separated; hind femora 



thickened III. Pachymeria. 



— Eyes in the male contiguous ; hind femora not thickened ... 4. 



4. Wings with the axillary angle obtuse; eyes contiguous 

 in the male narrowly separated in the female, epistoma 

 very narrow in both sexes ; only one notopleural bristle ; 



hind legs considerably elongated; body black, shining IV. Lissempis. 



— Wings with the axillary angle acute; eyes contiguous 

 in the male, broadly separated in the female ; epistoma 

 more or less broad; more than one notopleural bristle. . . 5. 



5. Upper branch of the discai vein abbreviated V. Co2)tophlebia. 



— Upper branch of the discai vein not abbreviated (in 

 E. livida both branches abbreviated just before the 

 margin) 6. 



