Phora. 187 



central bristles. Sciitellum with two bristles, likewise large. Pleura 

 bare. Abdomen robust. Hypopygium somewhat large, bent more 

 or less in under abdomen; the hypopygium has newly been thoroughly 

 studied by Schmitz (1920, Jaarb. Natuurh. Genootsch. Limburg 1919, 

 112, Fig. 1 — 7), and it yields the best characters for recognizing the 

 species; it is unsymmetrical ; on the right side the tergite bends down 

 and passes into the lower part (ventral plate), whereas on the left 

 side the upper and lower part are completely separated from each 

 other; the lower part (or ventral plate) does not reach quite to the 

 end of the hypopygium; the upper part forms behind on each side a 

 prolongation, betw^een which the opening for the anal tube is, these 

 prolongations form together a kind of forceps, but the arms are quite 

 unsymmetrical; on the left side the upper part passes evenly out 

 into the arm and this is in most species divided into an upper and a 

 lower lobe by a long fissure which from the upper margin goes down- 

 wards and then curves forwards towards the base; in some species 

 the arm is undivided ; the right arm is generally smaller and in contra- 

 distinction to the left it is articulated to the basal part; the lower 

 part or ventral plate has on each side behind a lobe or process which 

 is, as a rule, long and slender on the left side, broad and lobe-shaped 

 on the right; the arms of the forceps are more or less hairy, especially 

 the lower lobe of the left arm, further there is at the inner end of the 

 fissure a group of more or fewer hairs, and on the right side there is 

 a row of hairs along the hind margin of the downwards bending side 

 part. The anal tube is quite short and hardly stretching beyond the 

 opening between the arms, it consists as usual of a longitudinally 

 divided tergite and an undivided ventral part, and it is hairy at the 

 end. When the hypopygium is in situ the whole anterior part, which 

 is smooth and shining, is retracted into the sixth segment, so that 

 almost only the arms of the forceps are seen, but the shape and 

 sculpture of these, especially of the upper lobe of the left arm, is of 

 great value for the specific distinction. Abdomen in the female has 

 the sixth segment a little elongated and shows at the end the usual 

 two small lamellæ. Abdomen is very sparingly and short haired. 

 Legs somewhat robust, in nearly all species the front tarsi are dilated 

 in both sexes, especially the four last joints, only in the male of 

 heterocerca they are not or slightly dilated; the hind femora have in 

 the male on the ventral side at the base a curious elevation or process, 

 sometimes accompanied by a group of hairs; the process differs a 

 little in shape in the various species; the coxal bristles are strong 



