PLATE VIII 



Figure 1. The proboscis of Musca nebulo, diagramatic, in side 

 vieAv. 



The part above b.c., and including it, is the rostrum. 

 The haustellum extends from this to d.s. The rostrum 

 is rotated backwards and upwards in retraction, on the 

 fixed point formed by the approximation of a.a. to cl., 

 the part being at the same time drawn up by r.h.p. 

 w.r., the membraneous wall of the rostrum. A portion 

 of the side wall of the fulcrum has been removed to 

 show the position of the dilator muscle of the pharynx. 

 The oral lobe of one side is seen from the inner 

 aspect, c.c., collecting channel, e.w., a part of the 

 external wall of the labellum, cut short. 



Figure 2. Two isolated rings from a pseudotracheal channel. 



Figure 3. A pseudotracheal ring in sitti, showing the bifid end, b., 

 with its attached membrane, and its flattened end, f. 



Figure 4. The arrangement of the free ends of the rings at the 

 open side of the pseudotracheal channel. Bifid ends and 

 flattened ends alternate. The last three figures, which 

 are of Calliphora erythrocephala, after Graham- 

 Smith. 



Figure 5. One of the prestomal teeth of Philaematomyia gurnet. 



Figure 6. The distal end of the labial gutter of Philaematomyia 

 insignis, showing the thickened lateral portions which 

 articulate with the discal sclerite. x 150. 



Figure 7. The labella of Lyperosia tninuta, in the position of 

 action. Drawn from a preparation fixed without clear- 

 ing. The direction in which the teeth and connected 

 structures lie is the reverse of that in the resting position, 

 m.b., the marginal bristles, which in the resting position 

 form a fringe at the distal end of the proboscis. 

 Compare figure 7, Plate XIII. 



Figure 8. The teeth and connected structures of Philaematomyia 

 insignis. The pseudotracheal channels are not 

 shown, x 500. 



