2 INTEODUCTION. 



The pupa is fixed or free; in the great division of the 

 OBTHOEEHAPHA it is mummy-like, that is to say, shewing more or 

 less in outline the parts of the future imago, the shape of the 

 head, antenna?, wings, and legs often being conspicuous ; in the 

 second great division, the CYCLOBBHAPHA, it is long egg-shaped, 

 bearing no resemblance to the future insect, and exhibiting no 

 parts whatever of the body in outline. 



In the perfect state (imago) Diptera are to be found practically 

 everywhere and irs every conceivable situation, a few species 

 occurring even in very high latitudes and desert areas. 



A general introduction to the whole order of the Diptera is not 

 contemplated in this volume, and the various parts of the insect 

 are sufficiently well known to the majority of entomologists not 

 to require more than a brief description. The following ex- 

 planatory paragraphs on the external anatomy of a fly are there- 

 fore curtailed as far as expedient. The genus Tipvla is selected 

 as an example owing to its being the chief genus of the TIPULID^E, 

 the dominant family included in the present work. 



Fig. 1. Diagram of a Tipula, to illustrate the parts of a Dipteron. 



Head:- 



f. Frons. 



v. Vertex. 



o. Occiput. 



p. Tip of palpus. 



n. Neck. 

 Thorax : 



c. Oollare or prothorax. 

 ms. Mesosternum. 



d. Dorsum (or mesonotum). 

 t.s. Transverse suture. 



s, Scutellum. 



ra. Metanotum. 

 mt, Metathorax. 



h. Halteres. 

 Legs : 

 c. Coxa. 

 /. Femur. 

 t. Tibia. 



t.x. Tarsus (joints 1-5). 

 Abdomen : 



1-8. Abdominal segments. 

 a. Genitalia. 



