EXTERNAL ANATOMY OF INSECTS. 419 
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 ergan seems a very complex 
machine, since the under-jaws or mazille are attached 
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 latter 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 (/abium) of 
which I am now speaking, by itself. Linné 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 mazilla, 
as the Jabium"; but sometimes he distinguishes the mid- 
dle piece by that name ; and the tongue, in the case of 
the stag-beetle, he denominates a proboscis (trompe)é. 
In the Hymenoptera he calls this part tongue, under-lip, 
and proboscis: but seems to prefer the last term*. Fa- 
bricius originally regarded the whole middle piece as a 
labium' ; but afterwards (though his definition is not ac- 
curate, since he assigns the palpz to the ligula, which he 
affirms is covered by the /abswm—circumstances by no 
means universal in Coleoptera) he considers this as con- 
sisting of ligula and labium®. Latreille at first regarded 
+ Prates VI. VII. XXVI. b. 
> De Geer iv. 124, ¢. iv. f. 12. iti, 415. £. xxi. fi 4. 
© Ibid. iv. 281—. ¢. xi. f. 7. 4 Ibid. 329. ¢. xii. f. 3. 
* Ibid. ii. 775—. ¢. xxvi. f. 10. be, be. 
£ Philos. Entom. 18. & Syst. Eleuth, 1. Pref. iv. 
Dee 
