EXTERNAL ANATOMY OF INSECTS. 437 
might be named. In fact, with the insects of this intire 
Order mastication seems merely a secondary, if it is at 
any time their use. Still comprehending in one view all 
the mandibulate Orders, though some use their mandi- 
bles especially for purposes connected with their econo- 
my, yet their most general and primary use is the division, 
laceration, and mastication of their food; and this more - 
exclusively than can be affirmed of the under-jaws (maz- 
tlle). ‘This will appear evident to you, when you con- 
sider that insects in their larva state, in which universally 
their primary business is feeding, with very few excep- 
tions use the organs in question for the purpose of mas- 
tication, even in tribes, as the Lepidoptera, that have 
only rudiments of them in their perfect state—while the” 
maxille ordinarily are altogether unapt for such use. 
The exceptions I have just alluded to are chiefly con- 
fined to the instance of suctorious mandibles; or those 
which, being furnished at the end with an orifice, the 
animal inserting them into its prey, imbibes their juices 
through it. This is the case with the larve of some 
Dytisci, Hemerobius, and Myrmeleon*; and spiders have 
a similar opening in the claw of their mandibles, which 
is supposed to instil venom into their prey’. 
Under this head I must not pass without notice an 
appendage of the mandibles, to be found in some of the 
rove-beetles (Staphylinide), as in Ocypus, Staphylinus, 
and Creophilus. In the first of these it is a curved, nar- 
row, white, subdiaphanous, submembranous, or rather 
cartilaginous piece, proceeding from the upper side of 
* In the Myrmeleon, or ant-lion, the suction is promoted by the 
action of a piston, that pumps up the juices. Reaum. vi. 369. 
* De Geer iv. 386—. #. xv. f. 10. See above, p. 121. 
