Dolichopodidae. 3 



the reception of the thumb-like prolongations of the second joint. It 

 is then also somewhat hollowed, and from the second joint issnes a 

 somewhat conical, collar-shaped and somewliat chitinised prolongation, 

 which fits into the cavity of the third joint (fig. 18), the real mem- 

 branous connection between the two joints being at the end of this 

 prolongation. The third joint bears a two-jointed arista, which is 

 dorsal, placed nearer the base or the apex of the joint, or it is sub- 

 apical or really apical. The arista may be shorter or longer than the 

 antenna itself (the three basal joints), sometimes shorter in the female, 

 ionger in the male, and it may in the latter sex sometimes be very 

 long, longer than the whole body; in a few cases it may also in the 

 male show dilatations at the end of both joints, or only at the apex. 

 Its first joint is shorter or longer, from quite short to very long, much 

 longer than the second joint, and then longer in the male than in 

 the female. The first antennal joint is more or less hairy or bristly 

 above, or it is bare (i. e. microscopically haired); the second joint 

 has small bristles at the apical margin, often longer above or above 

 and below; the third joint is generally more or less distinctly hairy, 

 and the arista hairy or pubescent, sometimes only microscopically 

 hairy or apparently bare; in a few cases the arista is more long- 

 haired, or almost feathery, Jowls are generally not at all developed, 

 only rarely present, and sometimes a little broad. The epistoma is 

 broader or narrower, generally narrowest in the male, and here, 

 when the eyes are approximated or touching below, very narrow to 

 quite disappearing. As the antennæ are generally placed above the 

 middle, the epistoma is somewhat high; it is generally bare or 

 apparently so, sometimes distinctly pubescent. The clypeus is higher 

 or lower; it is not really separated from the epistoma, but it is 

 however more or less marked off; the dividing line is generally 

 marked by a small nodule or elevation at each side, often with a 

 little notch; sometimes it is more marked off by a transverse keel or 

 ridge; it is not rarely bent a little inwards, thus forming a small 

 angle towards the epistoma, and often it is somewhat arched, while 

 the epistoma is flat; its lower margin is straight or rounded, some- 

 times somewhat angular. Sometimes the clypeus reaches to or a 

 little below the lower margin of the eyes, but generally it is shorter; 

 rarely it reaches far below the eyes (the males of the American 

 genus Polymedon). The height of the clypeus is always easily made 

 out, also when it is only slightly marked from the epistoma, for 

 while the margins of the latter are in connection with the eyes, this is not 

 the case with the clypeus, the side margins of which are free, so that it is 

 only connected with the epistoma above. (Figs. 1 and 2). As the clypeus 



