XVIII INTRODUCTION. 



Dorsoplenral sat are, the suture running from tlie humerus to 

 the root of the wings, separating the mesonotum from the 

 pleura. Mik projDOses for it tlie rather more appropriate term 

 of notojjJ eural suture. 



Sterno^deuval svture, the suture below the dorsopleural 

 suture, nearly parallel with it and separating the mesopleura 

 from the sternopleura. 



Mesopleural suture, the suture running from the root of the 

 wings downward and separating the mesopleura from the 

 pteropleura. 



Mesophmra, the space situated in front of the root of the 

 wings, between the dorsopleural and sternopleural sutures. 



Pteropleura, situated below the root of the wings, back of 

 the mesopleural suture. 



Sternopleura, the lower part of the pleura, below the sterno- 

 pleural suture and above the front coxae. 



Htipjopleura, the space over the middle and hind coxse, be- 

 low the metapleura and pteropleura. 



Metajtleura, the "sides of the metanotum", a more or less 

 swollen space at the outside of the metanotum and between it 

 and the pteropleura and hypopleura. 



Metanotum, the oval, arched portion behind, beneath the 

 scutellum. It is frequently the best developed in the flies 

 with long, slender abdomen, as the Tipulida?. 



Halteres, balancers or poisers, rudimentary posterior wings, 

 a slender organ with a dilated head, situated below each 

 metapleura. 



Te(/uUv or aluhr, a pair of membranous scales situated 

 above tlie halteres and back of the root of the wings, one 

 above the other. The lower one or both may be rudimentaiy 

 or absent; the upper one moves with the wings and is called 

 the antitegula by Osten Sacken. Comstock, however, objects 

 to this use of tegula, saying that the term Avas first used 

 for the cup-like scale above the root of the wing in certain 

 hymeno])tera. an<l should be reserved for tliat organ. 



