80 Orthorrhapha brachycera. 



what upwards. Hypopharynx is of the length of the proboscis, 

 straight, pointed and a little dilated at the apex; it is somewhat 

 semitubular. Labium is long and narrow, tlie labella are about one 

 third of the length of the basal part of labium and not broader, they 

 are cleft to their base and hairy below and at the apex; the basal 

 part of labium is well chitinised. There is a long connecting mem- 

 brane at the base of labium, and when this is stretched out the 

 labium reaches far beyond the labrum; in rest this membrane is 

 folded in and (generally, in some species not) likewise the oral cone, 

 the clypeus is then withdrawn into the oral aperture. Thorax is al- 

 most rectangular, somewhat arched above; prothorax is distinct, ring- 

 like, or sometimes {Xanthempis) specially developed; it has variously 

 arranged bristles above. There is a narrow metanotum, but no meta- 

 sternum, the whole space between the hind coxæ and first ventral 

 segment being membranous. There are dorsocentral and most fre- 

 quently also acrostichal bristles, but they may be variously developed, 

 more or less numerous, longer or shorter and present in one or more 

 rows; the acrostichal bristles may be absent; the bristles are generally 

 longer and stronger behind. Besides there may be smaller hairs on 

 the sides of the disc. There are generally humeral, posthumeral, 

 some notopleural, a supraalar and a postalar bristle, but some of 

 them may be absent. Scutellum has two to several marginal bristles; 

 metapleura have stronger or weaker bristles which are more or less 

 numerous. Abdomen is somewhat long and more or less slender, 

 generally more slender in the male than in the female. It consists of 

 eight segments, but the last is sometimes hidden. The first segment 

 is short, on the dorsal side broader than the following, the second is 

 the longest. Sometimes the first ventral segment seems not to be 

 chitinised, thus there is in tessellata a distinct but very short first 

 ventral segment, but in livida I could find none, so that it is either 

 not chitinised or not separated from the second segment. The male 

 genitalia may be of very various aspects and larger or smaller, but 

 whatever the shape may be they seem alvvays to consists of two 

 pairs of lateral lamellæ, the upper and the lower; the upper lamellæ 

 are however generally or always more or less connected with each 

 other at the base or above. Penis is likewise of somewhat various 

 shape, thread-like or thicker, simply curved or more sinuous and 

 curved upwards between the lamellæ. At the ventral base of the 

 penis there is (generally or always) a smaller or larger ventral lamella. 

 The eighth abdominal segment seems to form a complete ring not 

 divided into a dorsal and a ventral half-ring. In the female the abdomen 

 tapers towards the apex; behind the eighth segment there is a small 



