254 Orthorrliapha brachycera. 



basal part somewhat longer than the labella: posteriorly it is divided 

 into two, somewhat long processes; the labella are broad, with hairs 

 at the margin. Thorax rectangular or nearly quadratic, somewhat 

 high, and a little arched above; pro- and metathorax small, the 

 former with small bristles above. The acrostichal bristles biserial and 

 somewhat long; there are six dorsocentral bristles, the first of which 

 may sometimes be somewhat small; further there is a humeral bristle 

 and some small hairs, a posthumeral, two notopleural, a præsutural, 

 three supraalar and a postalar bristle; the front part of the disc 

 has short hairs, some of which may however be somewhat long. The 

 propleura have numerous hairs both above and below. Scutellum 

 bare above, it has two long marginal bristles, and at each side one 

 or several smaller hairs or bristles. Abdomen cylindrical, a little 

 narrowed towards the end; the first dorsal segment is shorter than 

 the second, the first ventral segment is very short, and seems to be 

 somewhat connected with the second; in the male the segments two 

 to five are of the same length, the sixth is shorter; on the ventral 

 side the fifth sternite is shorter than the tergite, the sixth is mem- 

 branous and folded up to receive the hypopygium ; the seventh seg- 

 ment is small and hidden. The hypopygium is short and roundish, 

 it is not pedunculated and is laid more or less up under the sixth 

 segment; its appendages are generally more or less long and distinctly 

 seen; there are ventral lobes of various shape, shorter or longer, 

 generally styliform or somewhat lancet-shaped ; the outer lamellæ are 

 generally long, attenuating thread-like from a somewhat broader base, 

 and not rarely forked; sometimes, but rarely, they are broader and 

 more lamelliform. In the female there are five normal abdominal 

 segments, the others are hidden ; sometimes the end of the sixth may 

 be seen; the ovipositor terminates with some spines above. Dot-like 

 impressions are visible on the second to fifth segments, and the ab- 

 dominal segments have shorter or longer hindmarginal bristles. The 

 legs are somewhat slender; sometimes the front legs are somewhat 

 short, or the hind legs somewhat robust and elongated; the front 

 tarsi in the males may have the first or the two first joints thickened 

 towards the end, or a little curved, and the middle tarsi may have 

 the last joints dilated; the hind metatarsus is from slightly longer to 

 a little shorter than the second joint. In many species the middle 

 or posterior coxæ have in the male a more or less strong, flat apical 

 spine; these spines are in reality formed of a number of close-standing 

 bristles, and sometimes they may be seen to be cleft at the end, or 

 to split up into very close-standing bristles; when the leg is laid in 

 potash and the coxa is pressed, the spine is easily divided into the 



