198 



A. L. MELANDER. 



tennse two- or three-jointed, the outer joint simple, not ringed, and 

 provided with a terminal or sub-dorsal arista of various length ; ver- 

 tex not hollowed ; empodia small, at least never swollen ; never more 

 than four posterior cells present in the wings, all of which are open ; 

 anal eaeal closed far from the border if present (except in the 

 Mythicomyiina;) ; second basal cell not confluent with the discal cell 

 if we except some of the species of Hemerodromia. 



In addition to these points, there are other characters peculiar to 

 the family. The body is rather long and slender, the thorax gener- 

 ally very prominent. The head is nearly spherical and attached 

 loosely to the thorax. Although never minute the head is often 

 small, a character made pronounced by the large thorax. The eyes 

 often occupy nearl}j the whole head, sometimes the males are holop- 

 tic, sometimes dichoptic ; in some cases the eyes of the female are 

 contiguous below the antenna?. Generally the females are dichoptic. 

 Of one species both sexes may have similar eyes, or the female may 

 be dichoptic and the male holoptic. At the insertion of the an- 

 tennae there is an emargination of the eyes, more or less deep and 

 wide. The eyes are nearly always bare and composed of small 

 omraatidia, which may be of uniform size or rarely larger above. 

 Three ocelli are present. On account of the variation in the size of 

 the eye there is a corresponding difference in the construction of the 

 gense. These are largest in Coloboneura, whereas in many of the 

 Empididse the eyes reach the oral margin, and the cheeks disappear. 

 The mouth-opening is small ; in some species, such as Flatypalpus 

 hians, it is relatively larger. The mouth may be surrounded by 

 small bristles, but no large oral vibrassse are ever present. The face 

 IS without a mystax, but in Empimorpha it is covered with long hair. 

 The proboscis, which is generally adapted for piercing, is variable 

 in length and structure. Sometimes it is minute and thickened, 

 often it surpasses the head and thorax, in which case it is either di- 

 rected backward or downward and is slender, or, more rarely, it is 

 directed forward and is then generally moderately thickened. Palpi 

 one- to three-jointed, bristly or not, projecting forward or applied to 

 the proboscis, ribbon like and slender, to oval, short, and broad. 

 Antennae porrect, generally diverging, approximated at the base, of 

 various shapes, generally three -join ted, often two-jointed. Most 

 often the basal joints are short and the third joint longer, rarely the 

 third joint is the shortest. The antennal appendage consists of a 



