INTRODUCTION. XXIX 



This attempt at subdivision, based upon the antennae and 

 palpi, was all that had been made until a comparatively recent 

 date. It is the classification followed by Loew in the first 

 volume of the Monographs published as late as 1860. In 

 1863 Brauer proposed a more rational division of the diptera 

 into the two suborders, Orthorrhapha and Cyclorrhapha, based 

 chiefly upon larval and pupal characters. Their characters 

 in a later publication 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 

 bursts 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 hard- 

 ened larval skin (forming the so-called puparium); the imago always 

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

 present; ptilinum usually present CYCLORRHAPHA. 



More recently Brauer has proposed a further subdivision of 

 the suborders into tribes and groups as follows : 



SUBORDER ORTHORRHAPHA. 



Section I. Nematocera. 



Tribe 1. Eucephala. Families Mycetophilidae, Bibionidae, Chiro- 

 nomidae, Culicidae, Blepharoceridae/^Simuliidse, Psychodidae, Pty- 

 chopteridae, Rhophidae. 



Tribe 2. Oligoneura. Family Cecidomyidae. 

 Tribe 3. Polym-ura. Tipulidse, Limnobiidae. 

 Section II. Brachycera. 



Tribe 4. Acroptera. Family Lonchopteridae. 

 Tribe 5. Platygenya. 



Group 1. Homodactyla. 



Superfamily 1. Notacantha. Families Stratomyidae, Xylo- 



phagidae. 

 Superfamily 2. Tanystoma. Families Tabanidaa, Acan- 



thromeridae, Leptidae. 



Superfamily 3. Bombylimorpha. Families Nemistrinidae, 

 Acroceridae. 



