14 Orthorrhapha brachycera. 



more or less raised on the front legs, whence Verrall says, "appear- 

 ing to be standing on tiptoe". In no other family does the sexual 

 dimorphism reach so high a degree as in the DoHchopodids ; the 

 larger majority possess in the males secondary sexual characters 

 more or less developed. These characters are in the first line adorn- 

 ments of the legs, such as more or less plumed dilatations of the 

 tarsi, especially the front or middle, more rarely the hind tarsi ; special 

 shape of, or special bristles on the tibiæ, and also special bristles on 

 the femora. But the characters are also found on other parts ofthe 

 body ; the antennæ, especially the third joint, is often longer in the male, 

 likewise the arista or its first joint, and the arista may show dilata- 

 tions; the epistoma is often narrower and of another colour than in 

 the female, and the mouth parts smaller. The wings may be broadened 

 or of special shape, or they may have a special venation, and some- 

 times also dark markings; the costa has sometimes thickenings. The 

 pulvilli, especially on the front tarsi, may be enlarged, even the claws 

 may be specially shaped (Loew), or they may be wanting, at all events 

 on the front tarsi (Diaphorus). Also the colour of the body may in 

 the male be different from that in the female (f. inst. Argijra). Even 

 when no adornments are present on the legs, the length of them, and some- 

 times the colour may be different from that in the female; furtherthe 

 hind tibiæ are often or generally more thickened towards the end in 

 the males than in the females, and there is not rarely, thus in most 

 DoUchopodinae, a little impression or furrow at the end on the dorsal 

 side, often with special, short, generally white hairs. The hind me- 

 tatarsus is generally stronger in the male than in the female, its base 

 is a little differently shaped, and sometimes (species of Medeterus) it 

 has in the male a little excision at the base, often with a little spine 

 or tubercle. Finally also the wings, when not specially shaped in the 

 male, often show however small differences from the female, such as 

 the bend of the discai vein being a little larger, and the posterior cross- 

 vein lying slightly nearer the apex, as Macquart has figured it for a 

 number of species (Ann. de la Soc. Ent. de Fr. 2, II, 1844, 177, PI. 4—5). 

 The Dolichopodids are all predaceous, feeding on other insects, 

 especially small and soft ones, and also on other small animals; in- 

 stances have several times been recorded; among others Loew says 

 in Mon. of Dipt. of North Am. II, 1864,4.: "The species ofthe genera 

 with a large proboscis, especially their females, can altogether engulf 

 small insects within their proboscis, as if they swallowed them, whereas 

 tliey only suck them out, and throw the remainder away". E. Becker 

 says (Denkschrift. d. Math-Nat. Cl. d. Kais. Akad. d. Wissensch. Wien, 

 XLV, 1882, 28), that it may be observed on the living specimens, 



