NATURAL SYSTEMS.— MACLEAY. 205 
one or two such, is by no means accurately ascertained, 
though enough is known of the Moxuusca to incline us 
to suspect that they are no less subjected, in general, to 
a circular disposition than the four other great groups.” * 
This, therefore, our author considers as one of those 
groups which, without actually forming a circle, yet 
evinces a disposition to do so; and it is therefore pre- 
sumed to be a natural group. But, to illustrate this 
principle farther, let us return to the circle of Verte. 
BRATA. This, as we see by the diagram, contains five 
minor groups, or circles, each of which is again resolv- 
able into five others, regulated precisely in the same way. 
The class Aves, for example, is first divided into ra- 
pacious birds (Raptores), perching birds (Jnsessores), 
gallinaceous birds (Rasores), wading birds (Grallatores), 
and swimming birds (Natatores) ; and the proof of 
this class being a natural group is, in all these divisions 
blending into each other at their confines, and forming 
a circle.t In this manner we proceed, beginning with 
the higher groups, and descending to the lower, until at 
length we descend to genera, properly so called, and , 
reach, at last, the species ; every group, whether large or | 
small, forming a circle of its own. Thus there are circles 
within circles, “ wheels within wheels” —an infinite | 
number of complicated relations ; but all regulated by 
one simple and uniform principle, — that is, the circu. 
larity of every group. 
(260.) Wemust return, however, to thenumber of divi- 
sions of which our author considers every natural group is 
composed ; because on this point he appears not strictly 
consistent with himself. We have seen, in the forego- 
ing diagram, that the first division of the animal king- 
dom are resolved into ten circles or groups, five large 
and five small. In the following passage, however, 
when speaking of this diagram, Mr. MacLeay seems to 
lose sight of these lesser circles, and reckons the larger 
* Hor. Ent. p. 322. 
+ First pointed out by Mr. Vigors, Linn. Trans. 
