42 ORTHORRHAPHA. 



Discal cell nearly always present, but absent in some genera of 

 EMPLOYE, DOLICHOPIDJS. PLATYPEZID^E, etc. 



" In all cases of doubt as to whether a fly belongs to the 

 BRACHYCERA or NEMATOCERA (and doubt could only arise in some 

 STRATIOHYID.E and LEPTID^E), because of an annulated, flagellum- 

 like 3rd joint at the antennae (as in RhacMcerus, Berts, Xylopliagus, 

 Coenomyia, etc.), the contraction of the anal cell towards the 

 wing-margin provides an infallible character." (Verrall, 1909.) 



" Larvae with parallel jaws, moving upwards and downwards, 

 or outwards and downwards, which are used for piercing, 

 hacking, boring or sucking. Head not fully developed, only 

 a jaw-case without ganglia present, which, however, sometimes 

 is almost a head, because of the outwardly projecting eyes. 

 Chain of ganglia beginning behind the jaw-case. Larvae with 

 rudimentary mouth-parts ; meta- or amphi-pneustic, and com- 

 posed of 10 to 12 segments." (Brauer.) 



Tables of Families in NEMATOCERA. 



1. Thorax with a conspicuous 



suture on the mesonotum (indistinct 

 but present in PTYCHOPTERIN^E). 

 Discal cell normally present. All the 

 veins equally distinct and complete . . Tipulidae, p. 265. 

 Thorax without a conspicuous V~ 

 shaped suture on the mesonotum 

 (except in incomplete form in some 

 BLEPHAKOCEBID-S:). Discal cell al- 

 ways absent, except in RHYPHIDJE . . 2. 



2. Wing with seven longitudinal veins 



(apart from the forkings of any of 

 these) reaching the margin of the 

 wing. Auxiliary vein always present. 3. 

 Wing with less than seven longitudinal 

 veins (apart from the forking of any 

 of these) reaching the margin of the 

 wing (except in Chironomus, in which 

 the auxiliary vein and 2nd longi- 

 tudinal vein are always faint) ...... 6. 



3. Wings bare, never with scales or hairs. 



Eyes rounded. Proboscis never formed 

 for biting ; palpi incurved .......... 4. 



Wings never bare, always thickly 

 covered with scales or hair, or both. 

 Eyes reniform (kidney-shaped). Pro- 

 boscis nearly always expressly formed 

 for biting, or at least capable of doing 

 so ; palpi in CULICIDJE stiff and 

 straight .......................... 5. 



4. Discal cell always present. Head in 



male holoptic (eyes contiguous), or 

 practically so. Antennae distinctly 

 jointed, the joints annular or oval . . Rhyphidae, p. 549. 



