110 



FIRST LESSONS IN ZOOLOGY. 



head when not in use. The structure of the tongue is very 

 curious. When the fly settles upon a lump of sugar or 

 other sweet object, or even upon the back of our hand 



FIG. 118. Proboscis of the house-fly. A , right side view ; B, view of the same 

 from above; C, semi -tubes of its false tracheae ; E, a tooth; F, arrangement of 

 teeth between roots of false tracheae. In A and B, I, labellurn ; o, operculum ; 

 p, palps; /, fulcrum; m, mentum. (Magnified.) After Macloskie. 



when covered with perspiration, it unbends its proboscis, 

 extends it,, and the broad knob-like end divides into two 

 flat, muscular leaves (B I), which thus form a broad sucker- 



FIG. 119. Head and proboscis of the blow-fly, e, eye; geranium; bp, basiprobos- 

 cis; p, maxillary palpus; pr, chitinous ridges uniting with the rudimentary 

 maxilla; lp, lower labial plate; mp, medi-, dp, disti-proboscis. 



like surface, with which the fly laps up liquid sweets, or 

 any matter which seems good to the fly's mind. 



The two flaps at the end of the proboscis are supported 

 upon a framework of strong but delicate rods which act as 



