384 SYSTEM OF INSECTS. 
instead of giving a general character of the Order,— 
which principally consists in the insects composing it be- 
ing Apterous, or never acquiring organs of flight,—to 
define each of these groups. 
Hlexapods ( Ametabolia Leach, Ametabola M‘L.). Sza 
legs may be regarded as the natural number in a// the 
insect tribes*: but our business now is with those Aptera 
whose body consists of ¢hree greater segments, and which 
in none of their states have ever more or less than szx 
legs, and consist of the three Linnean genera Pediculus, 
Lepisma, and Podura (Thysanura Latr. and Anoplura 
Leach). Some of the mites (Acarus L.) are hexapods, 
but their body has no distinction of head, trunk, and ab- 
domen. The metamorphosis of most female Blatte, and 
of some other Orthoptera that are apterous, cannot be 
regarded as materially different from that of the Hexa- 
pods. Amongst the Anoplura,—the Pediculi, or lice, are 
suctorious, and the Nirm7, or bird-lice, masticators,—a 
circumstance which in them does not appear to indicate 
even a different Order, and proves that undue stress ought 
not to be laid, independently of general characters, on 
the mode in which insects take their food. 
Der. Metamorphosis complete. 
Body consisting of three principal segments. 
Mouth perfect, or rostellate>. : 
Antenne distinct. 
Legs six, in every state. 
Octopods. This suborder consists of the Trachean 
Arachnida of Latreille, excluding the Pycnogonida; of 
* Von. TIL. wdi supr. » Ibid. p. 472. 
