20 



GENERAL BIOLOGY 



jects a long, slender hairy tongue, that is itself retractile, 

 and that bears a minute membranous nectar-lapping 

 lobe at its tip. These parts seem at first very unlike 

 labium and maxilla of the grasshopper, but it is not 

 difficult by separating them and examining them 

 carefully to recognize their identity. In the accompanying 

 figure (fig. 13) the parts are all indicated by name; and the 

 proboscis of a short-tongued bee is 

 similarly drawn and lettered to make 

 their recognition easier. It will be ob- 

 served that in the honey bee the long, 

 tubular terminal joint of the proboscis 

 is composed of the hollowed out laciniae 

 of the maxillae and basal segments of 

 the labial palpi, closely applied together. 

 In the flies (Diptera) labrum and 

 mandibles are rudimentary, the rudi- 

 ments of the maxillae are intimately 

 combined with the highly specialized 

 labium to form the proboscis, which 

 is hollow, retractile beneath the head, 

 its terminal joint folding downward, 

 much as in the bees: but at its tip, 

 instead of the hairy, decurving, pro- 

 trusible tongue, there is often developed 

 a pair of up-folding, opposible flaps 

 (labellae) with corrugated inner sur- 

 faces (fig. 14). Since investigators are 

 not wholly agreed as to the identity of 

 parts in the fly labium, it will be suffi- 

 cient if the student note its length, its 

 folding and extension, the action of its labellae, and other 

 characters that have to do with pollen and nectar gathering. 



FIG. 13. Comparative 

 diagrams of probos- 

 cis of long-tongued 

 and short-tongued 

 bees. Upper figure, 

 the honey bee 

 (Apis). Lower fig- 

 ure (Halictus, from 

 Dr. W. A. Riley) ; 

 a, labrum; b, man- 

 dibles; c, maxillae; 

 d, labium; p, pal- 

 pus. 



