THE ENTOMOLOGIST. 



37 



Figs. 5 tl" G. — Mycetophila. Macrocera. 

 A" .7 



The above figures, and others which will follow, are from 

 the drawings of A. H. Ilaliday. The same letter refers to the 

 same parts in all the figures. 



One of the chief attractions in noticing the Diptera is the 

 great variety of their manner of flight, and this corresponds 

 with the difference of structure in the wings. These variations 

 will be briefly traced in some notes, which are preceded by 

 the following extract from the MSS. of A. H. Haliday on the 

 same subject. 



"The subcostal areoletlics between the costal vein and the 

 first longitudinal vein, usually the mediastinal (but if this vein 

 is effiiced, then the subcostal). 



" The mediastinal areolet lies next beyond this, between the 

 mediastinal and subcostal veins; and if the mediastinal vein 

 is wanting there is no mediastinal areolet. 



" The radial areolet lies between the subcostal and radial 

 veins ; if the latter divides into two branches at the end, 

 another radial areolet is enclosed between them; and in 

 either case, if the radial vein is connected with the subcostal 

 by a transverse vein, the radial areolet may be thus divided 

 into more than one. This areolet may become entirely closed 

 without extending to the margin, in case the radial vein 

 rejoins the subcostal before the end, as in Laphria, Volucella, 

 Hirmoneura, and Midas. 



