ON THE LIFE HISTORY OP UGIMYA. Ö 



these processes is ])rovicled with a muscle: those (i) on the upper pro- 

 cesses serve to project the basi-proboscis forwards, while those (//) on 

 the lower tend to retract it into a cavity of the head provided for its 

 reception. The upper sur£iC3 of the pharynx is partly hard and chiti- 

 nous, and partly membranous. On either side of the membranous 

 portion lies a chitinous oval disc (c) beset with a few hairs. Each of 

 these discs bears a single jointed palp (d) covered also with hairs, and 

 from its insertion on the disc there extends laterally a fine hairy chiti- 

 nous rod (r), so that the disc seems to be a modified form of a maxilla. 

 The proboscis proper (B) is composed mainly of the labium (j) which 

 assumes a form of short wide trough, and on its upper side in the 

 median line there is found a lancet-like arched chitinous body — the 

 modified labrum (c) — under which lies a jointed stylet. 



On each side of the base of the labrum is inserted a long chitinous 

 rod (/) which runs posteriorly to the side of the basi-proboscis. This 

 rod seems to correspond with the rudimentary first maxilla which 

 Kraepelin (5) has observed on the proboscis of Musca. 



The free end of the labium is furnished with a somewhat tri- 

 angular fleshy disc — the labellas (g). It is divided into two flaps by 

 two air tubes (w), which pass upwards in the middle line of the fleshy 

 disc to its top, and then bending laterally at right angles extend to 

 each side of it. From these air-tubes numerous fine branches of air- 

 tubes — pseudo-tracheœ — pass regularly towards the periphery of the 

 flaps. 



On the outer surface ( i) of the labellœ where two pointed processes 

 of the labium lie, is situated a T-shaped chitinous piece (/û). The 

 axis of this piece extends longitudinally between the two flaps of the 

 labellœ, and the two arms on its top extend towards the margin of each 

 flap respectively. By the action of these, the flaps when not in use 



(5) Zeit fur Wiss. Zool. Band 39. 1883. 



