392 SYSTEM OF INSECTS. 
thing like elytra and a scutellum appear to distinguish 
these insects. 
Def. Metamorphosis incomplete. 
Body apterous, compressed. 
Mouth rostrulate a . 
Tarsi pentamerous. 
We are now come to those insects which, though they 
change their skin in their progress to their state of per- 
fection, and some of them, as we have seen b , gain addi- 
tional segments and pairs of legs, yet none of them ac- 
quire wings or wing-cases : these I have considered as 
forming one Order, under the denomination of 
12. After a c (Synistata, Antliata, Unogata, Mito- 
sata F.). I do not give this as a natural Order. Our 
knowledge, however, of the internal organization of its 
groups, is not at present sufficiently matured to warrant 
the formation of them into new Classes' 1 : till that is more 
fully ascertained, it seems to me therefore best to con- 
sider these groups as forming three Suborders : the Jirst 
consisting of the Hexapods ; the second of the Octopods ; 
and the third of the Polypods. It will be better, I think, 
instead of giving a general character of the Order, — 
which principally consists in the insects composing it 
being Apterous, or never acquiring organs of flight, — to 
define each of these groups. 
Hexapods {Ametabolia Leach, Ametabola M C L.). Six 
legs may be regarded as the natural number in all the 
* Vol. III. p. 470. '' Ibid. p. 23. 
From '/, priv. and trrt^w. ri Vol. III. p. 221 — . 
