54 Orthorrhapha brachycera. 



The antennæ consist of five joints, the first is longer than the second, 

 the third is compressed, broadest at the base, somewhat pointed to- 

 wards the apex, the two last form an arista with the first joint short. 

 The eyes have the facets in front, from the inner eye-margin some- 

 what outwards, more or less enlarged in both sexes. On the back 

 of the head, below the occipital foramen, there is a membranous part 

 with the united stipites of the maxillæ. The clypeus is distinctly 

 marked off below the epistomal cailus, it is rounded upwards and 

 impressed. Proboscis directed downwards and more or less for- 

 wards; it varies in length from half as long to slightly longer than 

 the head is high; the basal part of the labium occupies about half 

 the length; the apex is rounded or more pointed. Labrum as long as 

 the basal part of labium, it is elongately triangular, rounded or trun- 

 cate at the apex. The maxillæ have a long, semitubular lacinia which 

 is either truncate {albiceps, forcipula, trigonus, atricapillus, cyanurus) 

 or somewhat pointed at the apex {e.g. crabronifonnis); the m.axillary 

 palpi are short, cylindrical, one-jointed. Hypopharynx likewise semi- 

 tubular, it is strong, pointed at the apex; it is beset with erect hairs 

 above over about the apical half. Maxillæ and hypopharynx equal 

 in length to labium. Thorax high, more or less arched above; it 

 is rectangular with rounded corners. There are præsutural, supra- 

 alar and postalar bristles, and on the middle of the disc there are 

 two rows of dorsocentral bristles, generally only on the hind part 

 (præscutellar bristles Ost. Sack.), more rarely continued longer forwards. 

 Scutellum has long marginal bristles. On meta- and hypopleura there 

 is a vertical row of more or less strong bristles. Metathorax distinct, 

 there is a somewhat large metasternum, the space between it and 

 the hind coxæ is membranous. Abdomen long, narrower than the 

 thorax and generally decreasing in thickness towards the apex; it is 

 cylindrical or somewhat compressed. It consists in the male of eight 

 segments; the first dorsal segment is short and always broader than 

 the foUowing segments, the second is the longest; the first ventral 

 segment is very short. The eighth segment is small and often more 

 or less hidden, it has sometimes, in the male, on the ventral side a 

 prolongation at the hind margin. The male genitalia consist of the 

 upper forceps which may be of somewhat different shape in the 

 different species; below the upper forceps is the lower pair of forceps the 

 arms of which are complicated and two-branched ; the inner branch 

 varies not a little in shape in the different species; between the arms 

 of the upper forceps lies the dorsal median lamella, it is membranous 

 in the middle, but chitinised at the sides and hence somewhat paired. 

 On the ventral side lies the ventral lamella at the base of the lower 



