EXTERNAL ANATOMY OF INSECTS. bi? 
(Pentatoma) with sharp fixed spines. But the protho- 
rax has moveable as well as fixed appendages; of this 
kind are those spines (wmbones), whose base is a spheri- 
cal boss moving in an acetabulum of the thoracic shield 
of the Capricorn subgenus Acrocinus. If 1 might hazard 
a conjecture, I should say that these organs were given 
to this animal by an all-provident Creator, to enable 
it to push itself forward, when in the heart of some tree 
it emerges from the pupa, that it may escape from its 
confinement. Another kind of moveable appendages are 
attached to the thorax of Lepidoptera, usually in the 
form of a pair of concavo-convex scales covered exter- 
nally with a tuft of hairs?. M. Chabrier, who examined 
these scales in recent insects, describes them as vesicles, 
which appeared to him full of a liquid and of air, and ca- 
pable of being alternately inflated and rendered flaccid ; 
he regards them as accessories to a pair of spiracles, 
which he looks upon as vocal>, opening into the mani- 
trunk just above the insertion of the arms. ‘These or- 
gans are quite distinct from the fegule that cover the 
base of the primary wings of insects of this Order *, and 
are what, borrowing a term from Mouffet ¢, I have called 
in the table patagza, or tippets. Under this head I may 
include the caruncles at the anterior angles of the pro- 
thorax of a genus of beetles with soft elytra, named by 
Fabricius Malachius. When pressed, says De Geer 
of these insects, a red inflated soft vesicle, of an irregu- 
lar shape, and consisting of three lobes, emerges from 
the thorax and from each side of the anterior part of the 
* Prats IX. Fie. 4. 
» Sur le Vol des Ins. c. vii. 374, t. xviil. f. 9. tt. 
© Prate IX. Fre. 5. 4 Theatr. Ins. 98. 
