EXTERNAL ANATOMY OF INSECTS. 4.23 
the tongue in three lobes or teeth which form two sinuses 
varying in depth *. 
The mentum taken by itself affords no very striking 
characters to which I need call your attention: I shall 
only observe, that in Hymenoptera it is generally of a 
triangular shape>: but before I proceed to consider the 
labial palpi, it will be proper to notice the remarkable 
labium of Orthopterous insects, and of the Libellulina, 
between which there is no little analogy. At first you 
would imagine the terminal part of this organ in the for- 
mer to be the analogue of the tongue, or ligula F.; as it 
is indeed generally regarded by modern Entomologists °. 
It seems, like the tongue of the predaceous beetles, to 
be a distinct piece, which has below it both dabiwm and 
mentum ; but when you look within the mouth, you will 
find a linguiform organ‘, which evidently acts the part 
of a tongue, and therefore ought to have the name; and 
the piece just alluded to must either be regarded as the 
termination of the lip, or as an external accompaniment 
of the tongue, analogous, it may be, to the paraglosse in 
beese. In a specimen of Acrida viridissima which I dis- 
sected, the tongue is as long as the appendage of the 
under-lip, and by its upper surface seems to apply closely 
to it. In the Lzbellulina a similar organ is discoverable f, 
which on its upper-side terminates in the pharynz, like 
that of one of the ground beetles before mentioned. In 
the Orthoptera, therefore, I regard the labium as con- 
sisting of three articulations, the upper one divided into 
* Plate XXVI. Fic. 24. bi. >» Prate VII. Fic. 3. a”. 
©. N. Dict. d’ Hist. Nat. xxiv. 171. 4 Prate VI. Fie. 6. e'. 
€ Prats VII. Fic. 3. i". £ Prate VI. Fic. 12, ef. 
