Asilidae. 3 



lies a dorsal median lamella of a somewhat paired structure or it 

 is divided into two styliform lamellæ; on the ventral side at the 

 base of the lower forceps lies a ventral median lamella, sometimes 

 very large. In the interior is the penis, generally curvcd upwards. 

 The female abdomen terminates in a shorter or longer ovipositor, 

 generally with a pair of lamellæ at the apex; often the eighth abdo- 

 minal segment forms part of the ovipositor, and in some cases even 

 the sixth and seventh. The legs are strong or more slender, some- 

 times very strong; in some cases they may be specially developed, 

 e. g. have the hind metatarsi very elongated, or thickened, or there 

 may be spines at the end of the front or the hind tibiæ. The legs 

 are hairy and more or less bristly, the bristles being of different 

 categories, very thin or stronger or very strong and spine-like, On 

 the ventral * or antero- ventral side of the front tibiæ and on the 

 posterior or postero-ventral side of the hind tibiæ there is a special, 

 short, dense pubescence, and similarly on the under surface of the 

 tarsi. All tibiæ have apical spurs. The claws are generally somewhat 

 strong; there are two, generally rather large pulvilli, sometimes they 

 may be rudimentary or even wanting {Leptogaster, Acnephcdum, Rha- 

 dinus, Psilinus); the empodium is strong and claw-like or weaker and 

 more bristle-shaped. Wings with the costal vein extending all round 

 the margin; the subcostal cell open or closed; the cubital vein forked, 

 sometimes (in non-Danish genera) the upper branch with a recurrent 

 veinlet or a vein prolonged to the radial vein; thus there are two or 

 three cubital cells. Discai cell formed exclusively of the discai vein; 

 between it and the upper branch of the postical vein a postical cross- 

 vein, or this cross-vein wanting and the postical vein uniting with the 

 discai vein only at a point or for some distance, and in the latter case 

 contributing to form the discai cell. There are five posterior cells, all 

 open or the fourth often narrowed at the apex or closed at a shorter 

 or longer distance from the margin. (In some non-Danish genera the 

 first posterior cell may also be closed). The anal cell reaching the 

 margin, open or closed. The basal cells of equal length or the second 

 shorter than the first. The alula generally well developed, rarely 



^ With regard to the different sides of the legs and the arrangement of the 

 bristles on them I use the method proposed by Mik (Dipt. Unters. Jahresber. 

 d. k. k. akad. Gymnasiums, 1878) and later on by Grinishaw (Entoni. Month. 

 Mag. 2, XVI, 1905, 173). When we consider all three pairs of legs as stretched 

 completely and horizontally out rectangularly to the body I term that side of 

 both femora and tibiæ which is turned upwards the dorsal or upper, and the 

 opposite the ventral or lower; the side which looks forwards is the anterior 

 or front side, and the opposite the posterior or hind side. 



1* 



