The Mouth-parts of the Nemoccra, etc. By W. Wcsche. 47 



only in the Cyclorrhapha that types of mouth-parts seem firmly 

 established, and the specialisations easily homologised. 



In the whole order, the mandibles are only present in a few 

 families, and even in those families they are often absent in the 

 males. The palpi are very variable, and when the maxillary are 

 present the labial are absent, though occasionally rudiments of the 

 absent part are found, more often of the maxillary than of the labial. 

 The paraglossre, which are considered typical of the order, only 

 occasionally disappear, as in the specialised Muscidse and the 

 Hippoboscidfe. The most constant parts are the stipites and 

 cardines of the maxilla3, which are only absent in the (Estridre ; 

 and it is very possible that a more comprehensive study of that 

 family than I have hitherto had the opportunity of making, may 

 show them to be present in some species. 



It follows from this constant variability, that the tropin cannot 

 be regarded as unfailing guides in classification, but I think that 

 this variability will be of assistance in considering the relations of 

 families ; on the other hand, the persistence of types in the 

 Cyclorrhapha makes the mouth-parts of great use in studying the 

 phylogeny of that sub-order. 



