INSECTA. 



141 



sucker with two, four, or six bristles ; feet moderately long ; 

 wings usually wide ; antennae with three articulations. Three 

 remarkable genera. 



Genus I. Tabanus, Lin. Gad-Fly. 



Head wide; sucker composed of six pieces, in the form of 

 lancets; proboscis projecting, with two lips. They resemble 

 large Flies, and are well known by the torments which they 

 inflict upon Horses and Oxen, whose skin they pierce for the 

 purpose of sucking their blood. 



Genus II. GEstrus. Bott. 



Hardly any vestige of mouth ; sucker composed of two setae, 

 appearance like that of a large hairy fly; antennae very short; 

 tarsi terminated by two hooks and two pellets. 



These Insects are rarely found in their perfect state. Each 

 species is generally a parasite of some species of mammife- 

 rous animal, and places its eggs upon whatever part of the 

 body is most suitable for its larvae. 



Genus III. Musca. Fly. 



Proboscis apparent, membranous, bi-labiate, and suscepti- 

 ble of being entirely drawn within the buccal cavity ; sucker 

 of two pieces. 



