240 FIRST PRINCIPLES OF NATURAL CLASSIFICATION. 
series of animals, we can never compare a typical group 
in one circle with an aberrant group in another ; for 
these groups, being of different denominations, would 
destroy at the very outset the harmony of the com- 
parison: it would render the law in question indeter- 
minate, and, therefore, no law. Every perfect group 
has its own typical and aberrant forms; and these are 
represented by the typical and aberrant forms in an- 
other perfect group. When, therefore, the toucans 
(Ramphastide), as a whole, are made to represent the 
entire group of Conirostres, the analogy or represent- 
ation is false; because the Ramphastide are admitted 
by all to be an aberrant family in the scansorial circle ; 
and the Conirostres are likewise admitted to be the 
typical group of another circle. But when, on the other 
hand, the Conirostres are stated to represent the Jnses- 
sores, then the analogy is true, because both of these 
groups are pre-eminently typical in their respective 
circles: although unequal in their rank or extent, they 
are equal in their denomination. This rule, however, 
by no means affects the comparison of the contents of a 
typical with those of an aberrant group ; for as each 
have types of perfection, so these types should justly 
represent each other. To vary our examples, we shall 
take an instance from two familiar animals in the class 
of quadrupeds. The Fer@ and the Ungulata are two 
natural orders; but one is typical, and the other aber- 
rant: yet as each of these ‘are circular, so their re- 
spective typical and aberrant groups may justly be 
compared as representing each other ; and this they ac- 
cordingly do. The tiger is one of the typical forms of 
\ Fere, and we see how beautifully it corresponds to the 
zebra, which is a typical form in the Ungulata. This 
,analogical resemblance does not consist merely in 
-the remarkable similarity of stripes on the two ani- 
‘mals, but actually extends to their moral character: 
both are vicious, wild, and untameable, and both are 
inferior to that form which is pre-eminent in each 
genus ; namely, the lion in one, and the horse in the 
