420 EXTERNAL ANATOMY OF INSECTS. 



2. Labium*. — On the under-side of the head, and op- 

 posed to the upper-lip, the mouth is closed by another 

 moveable organ, concerning the nomenclature and ana- 

 logies of which Entomologists have differed considerably. 

 At the first view of it, this organ seems a very com- 

 plex machine, since the under-jaws or maxillce are at- 

 tached to it on each side, and the tongue is often seen to 

 emerge from it above, so as to appear merely a part of it; 

 but as the former answer to the upper-jaws, and the lat- 

 ter is the analogue of the part bearing the same name in 

 .the vertebrate animals, I shall consider these as distinct 

 and primary organs, and treat of the under-lip {labium) 

 of which I am now speaking, b}^ itself. Linne takes no 

 notice of this part, but his illustrious compatriot and co- 

 temporary, De Geer, did not so overlook it : he appears 

 to consider the whole apparatus, including the maxillce, 

 as the labium^; but sometimes he distinguishes the mid- 

 dle piece by that name c ; and the tongue, in the case of 

 the stag-beetle, he denominates a proboscis (trompe) d . 

 In the Hymenoptera he calls this part tongue, under-lip, 

 and proboscis : but seems to prefer the last term e . Fa- 

 bricius originally regarded the whole middle piece as a 

 labium f ; but afterwards (though his definition is not ac- 

 curate, since he assigns the palpi to the ligula, which he 

 affirms is covered by the labium — circumstances by no 

 means universal in Coleoptera) he considers this as con- 

 sisting of ligula and labium*. Latreille at first regarded 



a Plates VI. VII. and XXVI. b. 

 b De Geer iv. 124. t. iv./. 12 iii. 415. t. xxi./. 4. 

 c Ibid. iv. 281—. t. xi./. 7- d Ibid. 329. t. xii./. 3. 



e Ibid. ii. 775— t. xxvi./. 10. b c, b c. 

 PMlos. Entojn. 13. b Syst. Eleuth. i. Prsef. iv. 



