322 EMPIDJE. 



Head comparatively small, sometimes very small, more or less 

 globular, generally bulging out posteriorly ; as wide as, or narrower 

 than the thorax ; joined to the thorax by a narrow neck. Eyes 

 large, often forming nearly the whole of the head, generally bare, 

 contiguous in both sexes or in the c? only, or separated in both 

 sexes ; in contiguous eyes the upper facets nearly always larger 

 than the lower ones ; in the middle of the inner eye-margin is an 

 incision of greater or less size, said to be always present and 

 perceptible ; three ocelli. Proboscis of various structure ; short 

 and thickened, of more moderate size both in thickness and length ; 

 or, as is frequently the case, horny, adapted for piercing, directed 

 forwards ; or elongate, in some species as long as the whole body, 

 and directed obliquely forwards, downwards, or backwards. Occa- 

 sionally the proboscis is curved. Mouth-opening generally small. 

 Palpi generally 1 or 2, rarely 3, jointed ; of various structure, 

 size, and length ; bare or bristly. Antennae porrect, approximate 

 at base, sometimes 2-jointed, generally of three unquestionable 

 joints, of which the 3rd may taper into, or bear, an arista, which 

 is always bare except when styliforrn. In some genera a pro- 

 minent 1- or 2-jointed style is present, and some authors have 

 described such antennae as being 4- or 5-jointed. Even in certain 

 genera in which they are regarded as 3-jointed, the 3rd joint 

 (in these cases nearly always elongate conical or pear-shaped) is 

 apparently of a different texture from the basal two, partaking 

 more of the nature of a style. In the present work the latter 

 genera are regarded as having a 3-jointed antenna, attention being 

 called to the structure of the 3rd joint. In the genera with so- 

 called 4- or 5-jointed antennae the 4th and 5th joints are regarded 

 as representing a style. Head with a few weak bristles on vertex, 

 frons, or occiput. 



Thorax of moderate size, often greatly humped, generally sub- 

 quadrate, the prothorax sometimes produced forwards. Scutellum 

 small, semicircular, or gently curved, with two or more bristles ; 

 a few bristles generally occur on the margin of the thoracic 

 dorsum. 



Abdomen of 7 or 8 segments,* bare or pubescent ; generally in 

 the <$ elongate, conical, or cylindrical, in some genera short, 

 rounded, or ovate ; io the 5 sometimes broader at the base, but 

 always more pointed at tip. Genitalia in <5 of various structure, 

 sometimes complex and prominent ; in usually in the form of 

 a slender conical ovipositor with two terminal styliform lamellae. 

 Abdomen never with conspicuous bristles. 



Legs exhibiting various forms of structure. In some groups 

 they are comparatively normal, that is to say, of moderate length 

 and thickness ; but in others the coxae may be greatly lengthened, 

 the femora (either pair singly or the whole of them) being often 

 conspicuously incrassated, and in some genera furnished with 

 spines below. The tibiae and metatarsi are sometimes enlarged, 

 whilst marked differences in sexual ornamentation not infrequently 



* Melander says 5 to 7. 



