Chaetoneurophora. 



99 



Female, In general appearance similar to the male, but often 

 paler; palpi larger -with bristles of ordinary length. Abdomen is of a 

 curious construction; the first foiir segments are of about equal 

 length only the first shorter, the tergite of the fourth segment is 

 narrowed behind, the fifth tergite is a very short and small, more 

 or less hidden plate, often quite hidden so that abdomen has appar- 

 ently only five tergites, the sixth segment is, as iisual, elongated; 



Fig. 39. 



Fig. 41. 



Fig. 40. 



Abdomen of Ch. thoracia $. 



Fig. 39 normally distended, from above; Fig. 40 with the sacks pulled out, 



from above; Fig. 41 the same from the side. 



on the ventral side the sixth segment has a large, chitinized ventral 

 plate; as well known the occurrenoe of siich a ventrite is very rare 

 among the Phorids, its occurrence here is, I think, due to the peculiar 

 construction of abdomen. The lateral hairs on abdomen are some- 

 what conspicuous besides the long hairs on second segment; on the 

 membrane to each side of the fifth tergite a bunch of bristles is seen, 

 when this part is not quite withdrawn. — Such is the construction 

 when abdomen is normally distended (fig. 39), but in certain circum- 

 stances the membrane with the bunch of bristles is capable of being 

 pulled out to a high degree, and it forms then on each side a large 



sack of orange colour, the sacks being connected in the middle at the 



7* 



