46 Transactions of the Society. 



surface, (2) are paired organs, and (3) occupy positions, which 

 several facts suggest that they represent the labial palpi (pi. III. 

 fig. 4). 



Summary. 



(1) On reviewing these eight groups, it is apparent that they 

 are artificial, so that families that are closely related to each other 

 are occasionally in different sections, though it oftener happens that 

 they are in neighbouring, or even in the same group. 



(2) It will also be seen that the Nemocera have characters in 

 the tropin, as well as in the antenna;. Examples of species with 

 four-jointed palpi and a ciliated hypopharynx will be found in every 

 family, and these parts may, when in that condition, be considered 

 as distinguishing characters — establishing a relationship with the 

 Asilidse and the Empidae, in the sub-order Brachycera. The palpi 

 are maxillary in every case, with the exception of the Bibionida?, 

 and it is difficult to understand why this family has deviated. 



(3) It seems that Dilophus gives the clue to the original situa- 

 tion of the labial palpi, (4) while Chrysops shows the palpigers ; 

 these have altered their position in the Muscidre, but are very 

 constant, and generally to be found at the base of the labial palpi. 



(5) That as a rule the males of the Culicidse are harmless, 

 but their trophi are variable, and may in some instances be fully 

 developed. 



(G) The mandibles of Anopheles differ from those of other 

 Culicidas. 



(7) In some males of the genus Culex, and related genera, is 

 found a false joint on the labium. This possibly marks the spot 

 where the labial palpi were articulated. In some genera this is 

 constant, in others variable. 



(8) The median apodemes in Tipula are a fusion of the 

 mandibles on the ventral, and of the cardines of the maxilla; on 

 the dorsal side. 



(9) Species exist in Diptera (apart from (Estridaj) in which 

 both palpi are aborted. 



(10) Homologisation of the trophi of the Dolichopida?, and their 

 aberration both from the Nemocera and Musca types. 



(11) Affinities exist in the trophi of Dolichopus and Phora. 



(12) The palpi in Glossina are labial. 



(13) The Hippoboscidffi are descended from blood-sucking 

 Muscida?. Homology of their trophi. 



(14) Archaic types of trachoe and maxilloe in the Ephydridre. 



(15) Gizzard in the submentum (fulcrum) of Drosophila. 



(16) The trophi in the different species of a family are some- 

 times variable, especially in the Brachycera. The Dolichopidee and 

 Empida? present the greatest divergences in this respect, and it is- 



