EXPLANATIONS OF PLATE III. 



Fig. J. Side view of the head of Eristalis horticola; dotted lines indicate 

 the courses of the tip of the proboscis, k, and of its middle joint, 

 g, in the retraction of the proboscis, d, angle of the head in which 

 the dorsal posterior process, d' (fig. 7), of the fulcrum is attached. 



Fig. 2. Longitudinal section of the head of E horticola, with partly retracted 

 proboscis. Lettering as in fig. 1. 



Fig. 3. Longitudinal section of the head of E. horticola, with extended pro- 

 boscis. Lettering as in fig. 1 and 2. 



Fig. 4. Detached maxilla and maxillary palpus of E. horticola. 

 Fig. 5. Tip of Iabru7ii-epipharynx of E. horticola, spread out and viewed 

 from beneath. 



Fig. 6. The hypopharynx of E. horticola, from above. 



Fig. 7. The fulcrum of E. horticola; d', its dorsal posterior process; z, its 

 ventral posterior process. 



