5 2 NORTH AMERICAN DIPTERA. 



tively recent date. It is the classification followed by 

 Loew in the first volume of the Monographs published as 

 late as 1862. In 1863 Brauer proposed a more rational 

 division of the Diptera into the two suborders, Ortho- 

 rrhapha and Cyclorrhapha, based chiefly upon larval and 

 pupal characters. Their characters in a later publica- 

 tion he gives as follows: 



Larvae with a 'jaw-capsule' (Kieferkapsel) or a differentiated head. 

 Pupae free or enclosed in the larval skin; in either case the larval skin 

 hursts for the extrication of the pupa or imago in a T-shaped opening 

 on the back of the anterior end, or rarely in a transverse rent between 

 the eighth and ninth abdominal rings. The imago lacks the frontal 

 lunule and ptilinum Orthorrhapha. 



Larvae without differentiated head. Pupae always enclosed in the 

 hardened larval skin (forming the so-called puparium ) ; the imago al- 

 ways escaping from the anterior end through a circular orifice. Frontal 

 lunule present; ptilinum usually present. . . Cyclorrhapha. 



More recently Brauer proposed a further subdivision 

 of the suborders into tribes and groups as follows: 



BRAUER'S CLASSIFICATION. 

 Suborder Orthorrhapha. 

 Section I. Nematocera. 



Tribe I. Eucephala. Families Mycetophilidae, Bibionidse, Chi- 

 ronomidae.Culicidae, Blepharoceridte, Simuliidae, Psychodidae, 

 Ptychopteridee, Rhyphidae. 



Tribe 2. Oligoneura. Family Cecidomyidae. 



Tribe 3. Polyneura. Tipulidae, Lininobiidae. 



Section II. Brachycera. 



Tribe 4. Acroptera. Family Lonchopteridae. 

 Tribe 5. Platygenya. 



Group 1. Homoodactyia. 



Superfamily 1. Notacantha. Families Stratiomyidee, 



Xylophagidae. 



Superfamily 2. Tanystoina. Families Tabanidae, Acan- 



thomeridse, Leptidae. 



Superfamily 3. Bombylimorpha. Families Nemistrin- 

 idae, Acroceridas. 



Group 2. Heterodactyla. 



Superfamily 1. Procephala. Families Mydaidae, Asil- 

 idae, Bombyliidae. 



Tribe 6. Orthogenya. Families Empidae, Dolicbopodidse. 



