446 EXTERNAL ANATOMY OF INSECTS. 
As the principal use of the mandibles is cutting and 
masticating, so that of the organs we are considering 
seems to be primarily that of holding the food and pre- 
venting it from falling while the former are employed 
upon it. I say this is their primary use; for I would by 
no means deny that they assist occasionally in commi- 
nuting or lacerating it. In fact, were there no organs 
appropriated to this use, and if both mandibles and maz- 
ille were employed at the same time in comminuting the 
food, it seems to me that it must fall from the mouth. 
In a large proportion of insects the lobes of the mazille 
are not at all calculated for laceration or comminution ; 
and in those tribes—as the Melolonthide, Rutelida, Dy- 
nastide—in which they seem most fitted for that pur- 
pose, the mandibles have znczszve teeth at their apex, and 
at their base a powerful mola or grinder: circumstances 
which prove, that even in this case the business of mas- 
tication principally devolves upon them. 
6. Palpi Mazillares*. ‘There is one circumstance that 
particularly distinguishes the mazxille from the mandi- 
bles—they are palpigerous, as well as the under-lip. The 
feelers, or palpi, emerge usually from a sinus observable 
on the back of the maxilla where the upper lobe and 
stalk meet. Their articulation does not materially differ 
from that of the labial palpi. Each mazilla has properly 
only one feeler; but, as was lately observed®, in certain 
tribes the upper lobe is jointed and palpiform, which 
has occasioned it to be considered as a feeler, and these 
tribes have been yvegarded as having six feelers. The 
most general rule with regard to the length of the palpi 
* Prates VI. VII. h’. » See above, p. 442. 
