450 EXTERNAL ANATOMY OF INSECTS. 
as to figure, of which this joint exhibits examples. The 
palpi in general at their vertex are often rather concave; 
and this concavity is formed by a thin papillose mem- 
brane, which it is supposed the animal has the power of 
pushing out a little, so as to apply it to surfaces. The 
primary use of the palpi of insects will be considered 
when I treat of their senses ; but they probably answer 
more purposes than one. For instance, when I was once 
examining, under a lens, the proceedings of a species of 
Mordella, which was busily employed in the blossom of 
some umbelliferous plant, it appeared to me to open the 
anthers with its maxillary palpi, and they often held the 
anther between them: when not so employed, they were 
kept in intense vibration, more than even its antennz ; 
and at the same time, as far as I could judge, an Elater 
made the same use of them. Mr. Curtis has observed 
that the long maxillary palpi of Xyela pusiila*, a hyme- 
nopterous insect of the family of Xiphydriadea, look like 
legs, and from those organs being placed far behind, he 
thinks it not improbable that these palpi may occasionally 
exercise the same functions. 
7. Lingua®.—This name was applied by Linné to the © 
part in insects representing the ¢ongue in vertebrate ani- 
mals; and as it performs most of the common offices of 
a tongue, and the pharynz is situated with respect to it, 
as we shall presently see, nearly as it is in those ani- 
mals, there seems no more reason for giving it a new 
name, than there is for giving a new name to the head 
or legs of insects, because in some respects they differ 
from those of the higher animals. I shall not therefore 
callit Zigula, with Fabricius and Latreille, nor Labzum, 
9 Brit, Ent. i. t. xxx. f. 4. 4 Prates VI. VII. XXVI. e’. 
