Dolichopodidae. 7 



opens into it through a hole always placed on the left side near the 

 base. The construction of the hypopygium is well described and 

 illustrated in a paper by Snodgrass (Proc. of the Californ. Acad. of 

 Se. 3, III, 273, 1904, PL XXX— XXXIII) with regard to several genera. 

 At the base the hypopygium is somewhat, more or less, unsymmetrical 

 on account of the seventh and eighth segment being placed at the 

 left side. On the ventral side it is deeply invaginated, the cavity 

 thus formed (genital chamber, Snodgrass) being open ventrally and 

 posteriorly; sometimes, when the hypopygium is short and roundish, 

 the opening is more apical than ventral. The sides of the cavity are 

 more or less raised and thin, and thus often forming more or less 

 distinct lobes, the ventral lobes; often the lobes are divided so that 

 there are middle ventral lobes and posterior ventral lobes, the latter 

 stretching beyond the end of the cavity. The middle lobes are some- 

 times unsymmetrical, this on one side being of another shape than the 

 other. The lobes may for the rest be of manifold shape and may 

 vary much in length, especially the posterior lobes may sometimes 

 be very long, and they may be variously, sometimes rather long- 

 haired. At the anterior end of the hypopygium the cavity is roofed 

 over, and from here arises the penis, which is thin, generally long, 

 and stretched backwards along the ventral side, often running between 

 the mentioned lobes; the penis is much curved in the basal part, as 

 it arises in reality inwards from the dorsal side; it is more or less 

 inclosed in a sheath of various structure. At the posterior side margins 

 of the cavity arise (generally) two pairs of appendages, the lateral 

 and median inner lamellæ, probably clasping organs; they are stretched 

 backwards, of various structure, often thin, more or less styliform 

 with various dilatations, and more or less curved towards each other. 

 Between them, more dorsally, there is a generally more or less hook- 

 like median appendage, the dorsal median appendage. All these 

 appendages are perhaps not always present. On the dorsal side at 

 the end the hypopygium is more or less, sometimes rather deeply 

 incised, and in this incision the smaU and hidden tenth segment is 

 placed. It bears two lamellæ, the outer lamellæ; these are smaller 

 or larger, and of very various shape, generally more or less scale- 

 like, or sometimes thread-like; for the rest they may be triangular, 

 roundish, elongated, sometimes very elongated, forked or of other 

 shape; they are generally hairy, and the margin is not rarely split 

 into teeth and has long, more or less curved bristles. Sometimes the 

 outer lamellæ are quite or partly united in the middle. According to 

 Snodgrass 1. c. the tenth segment bears the anal opening. This author 

 is of opinion, that the outer lamellæ have no direct connection with 



