514 EXTERNAL ANATOMY OF INSECTS, 
divided into two sections, distinguished by forms ex- 
tremely different: those, namely, that are employed by. 
insects as ¢actors to explore their way, and those that 
cannot be so employed. ‘The great majority are of the 
former kind; but those that may be denominated setzge- 
rous,—as the antennee of the Libellulina, Ephemerina, of 
the Homopterous Hemiptera, and of many Diptera, the 
last joint of which terminates ina bristle, or is furnished 
with a lateral one, and of some gnats that have short 
feathered antennz,—appear not fitted to be used as tac- 
tors to explore by touch, and form the latter description. 
This difference in these organs, as I shall have occasion 
to prove more at large hereafter, furnishes a strong pre- 
sumption that their pr7mary function is not touch. Were 
this the case, it would be common to them all. 
As to their s¢ructure, antennee consist in general of a 
number of tubular joints ; each of which having separate 
motion, the animal is thereby enabled to give them every 
flexure necessary for its purposes. ‘The scape, or first 
joint, by means of the buib inosculates in the forulus, or 
is suspended to it; and the others, sometimes by a simi- 
lar, though less pronounced knob at their base, inoscu= 
late in the preceding one; but in some cases-the inoscu- 
lation seems not so perfect, the joints being simply sus- 
pended by ligameut. In pectinated or lamellated an- 
tennee, the branch is usually a lateral process of the joint 
from which it issues; but in Phengodes its involute plu- 
mose branches appear to articulate with the apex of each 
joint*. I have a specimen of one of the Cleride, of a 
genus undescribed, in which each branch is forked. In 
some tribes of the Capricorn beetles (Stenocorus, &c.) 
Pratt XXY. Fic. 4. 
