ANALOGICAL TESTS OF CIRCLES. 333 
the ocean, instead of the forest. These groups, there- 
fore, are analogous, and do not disturb the harmony of 
the series. We therefore pass onward to the last, namely, 
the Crateropodine, or strong-legged thrushes, which we 
compare with the order of Rasores, or the gallinaceous 
birds. If an ordinary observer was asked what were the 
most conspicuous distinctions of the gallinaceous order, 
he would undoubtedly mention as among the first, the 
great size and strength of their feet, and their short and 
comparatively feeble wings. The first of these pecu- 
liarities, in fact, is absolutely essential to them, because 
they habitually live upon the ground; while the last, 
which in a tribe of flying birds would be an imperfec- 
fection, among these is in perfect harmony with their 
general habits. It would, moreover, be remarked, as a 
third distinction of the rasorial group, that it contains 
the largest birds in creation ; witness the ostrich, cas- 
sowary, bustard, &c. Now what the rasorial order is to 
the whole feathered creation, the Crateropodine are to 
the family of thrushes ; they have, as their name im- 
plies, the strongest feet, they have the shortest wings, 
and they are the largest birds in their particular group. 
With three such strong and remarkable points of analogi- 
cal resemblance, there can be no doubt that the Cratero- 
podine are the representatives of the Rasores ; or, in other 
words, that these two groups are parallel and analogous. 
(409.) When results like these attend the com- 
parison of a doubtful circle with one that is universally 
deemed to be natural, there is good reason to believe that 
we have discovered the true series ; for, however fancy 
might deceive us in the first formation of a circle, it is 
impossible to believe that so much harmony would result 
from an erroneous application of a theoretical truth. 
Nevertheless, it must be remembered that our group 
has yet only been proved by one test. It has been 
compared with the circle of the leading orders of birds ; 
but this is not sufficient for complete demonstration. 
The analogies, although strong, are nevertheless remote ; 
and it therefore is expedient, if not essential, that our 
