﻿6 ARKIV FÖR ZOOLOGI. BAND 4. NIO 10. 



denza all' apice del rostro si ripiegano in alto formando una 

 specie di cappuccio all' estremitå del rostro stesso.» 



Instead of the real hypopharynx which Silvestri has 

 thus overlooked, he interpretes as hypopharynx a structure 

 which is to be found on the ventral side of what he consi- 

 ders to be the coalesced maxillae. 



The labium^ (Textfigs 1 and 2) is two-jointed: the basal 

 joint (mentum) is only slightly longer than the terminal joint; 

 it exhibits a median longitudinal ridge with broad basis 

 which branches off nearly at right angles into two short 

 diverging ridges a t the base of the terminal joint. 



The terminal joint is composed of the two labial palps 

 or labellse, which are firmly connected with each other by a 

 thin membrane; it is capable of being bent upwards at a 

 right angle by means of two powerful bundles of muscles 

 which are inserted at its hind edge and seem to attach 

 themselves to the thickened hind part of the ridge of the 

 mentum. 



The labellae increase in width towards the tip and their 

 lateral edges become curved more and more upwards and 

 inwards so as to meet in the middle and form a kind of 

 hood immediately in front of the labrum. 



The dorsal half of the anterior edge is rounded, the 

 ventral one is excavated, so that the labium on dorsal view 

 seems to end in two rounded lobes. while on ventral view it 

 is semicircularly excavated, with a small, rounded median lobe 

 (Textfig. 2). 



The labellse are provided with small hairs, the cutiele is 

 very thin and soft, the anterior edge is not smooth but finely 

 wrinkled. 



In the distal half of the labium there is a median longi- 

 tudinal chitinous thickening, with a groove in the middle 

 which coalesces with the inner surface of the labium; it widens 

 near the tip suddenly to about half its ordinary breadth and 

 terminates in a free point. 



This structure I homologize with the hypopharynx of 

 the Diptera. 



^ As the labium got löst thi-ough an accident af ter the drawing 

 (Textfig. 2.) had been made, and it had been dissected from the rest of the 

 mouthparts and delineated on ventral view (Textfig. 1) I am unable to 

 doscribe the proximal half of the inner (dorsal) surface of it. 



