DIPTERA. 487 



cumbent on the body. The antennae terminate in a palette, almost 

 always accompanied by a seta. The palpi of the greater number 

 are flattened or laminiform, and laid on the proboscis. 



These characters, a body compressed on the sides, a triangular 

 head, slightly projecting in the manner of a snout, the abdomen 

 curved underneath, and long slender legs furnished with little spines, 

 particularly distinguish the genus 



DOLICHOPUS, Lat. Fab. 



Which now forms a small tribe. These Insects are frequently green or 

 cupreous. The legs are long and very slender. They are found on walls, 

 trunks of trees, &c. Some of them run along the surface of the water 

 with great celerity. 



FAMILY III. 

 TABANIDES. 



Our third family of the Diptera is characterized by a salient pro- 

 boscis, usually terminated by two lips with projecting palpi, by the 

 last joint of the antennae being annulated, and by a sucker composed 

 of six pieces: it comprises the genus 



TABANUS, Lin. 



Or the Horse-flies. These Diptera are very similar to large Flies, and well 

 known by the torment they occasion to cattle, by piercing their skin in 

 order to suck their blood. Their body is usually but slightly pilose. 

 Their head is as wide as the thorax, almost hemispherical, and with the 

 exception of a small space, particularly in the males, occupied by two eyes, 

 generally of a golden-green, with purple spots or streaks. Their antennae 

 are about the length of the head, and are composed of three joints, the 

 last of which is the longest, terminates in a point, has neither seta nor stilet 

 at the end, is frequently lunate above its base, and with from three to seven 

 transverse and superficial divisions. The proboscis of the greater number 

 is almost membranous, perpendicular, of the length of the head or some 

 what shorter, almost cylindrical, and terminated by two elongated lips. 

 The two palpi, usually incumbent on it, are thick, pilose, conical, 

 compressed and biarticulated. The sucker inclosed in the proboscis is 

 composed of six small pieces, in the form of lancets, which, by their num- 

 ber and relative situation, correspond to the parts of the mouth in the Co- 

 leoptera. The wings are extended horizontally on each side of the body. 

 The alulae almost completely cover the halteres. The abdomen is triangu- 

 lar and depressed. The tarsi are furnished with three pellets. 



