62 INTERNAL ANATOMY OF INSECTS. 
are distributed to every part of the body*. The first of 
these tubes are called the trachea and the latter the 
bronchia. This structure appears, however, not to be 
universal: it is to be found in caterpillars and many 
Dipterous larvee; but in that of the rhinoceros-beetle 
(Oryctes nasicornis) and other Lamellicorns, the bronchie 
branch directly from the spiracle, the bottom or interior 
mouth of which is lined by a membrane from which they 
proceed’: something similar has been observed to take 
place in many insects in other states, as the common 
cockchafer®; the pupa of Smerinthus Populi’; in the 
Cicade®; in the Locust tribe‘; and many others. In 
the Cossus, or larva of the great goat-moth, the trachea 
commences with the first spiracle, and finishes a little 
beyond the last, after which it diminishes considerably 
in diameter, and terminates in several branches or bron- 
chia, which proceed to the anal extremity of the body. 
The bronchie which originate from the trachee in the 
vicinity of each spiracle, may be considered as consisting 
in general of three packets ;—dorsal ones, which are dis- 
tributed to the back and sides of the animal; visceral 
ones, which enter the cavity of the body, and are lost 
amongst the viscera and the caul; and gastric ones, 
which dipping from the trachee overrun the lower part 
of the sides and belly*. 
The trachee and bronchie consist of three tunicsi: the 
4 Prate XXI. Fie. 3. 4. > Sprengel Commentar. t. i. f. 1. 
© Ibid. f. 10. OP bid wi laps 
* Malpigh. De Bombyc. t. iii. f. 3. sy lbid-ts ivnufele 
® Lyonnet Anat. 101. h Ibid. 
' Sprengel (wi supr. 16.) says that he never found more than two; 
but as Lyonnet affirms that he has very often separated them (102), 
his accuracy cannot be questioned. 
