that connect the Orders and Families of Birds. 401 
groups will appear, of whose place in nature I must speak with 
hesitation. But while it must be acknowledged, that some defi- 
ciencies will intervene in the chain of evidence by which I would 
endeavour to establish the existence of a uniform succession of 
affinities in the feathered creation, it must be equally observed, 
that there is no contradiction toit. The chasms that occasionally 
present themselves are such as may be supposed to originate in 
our limited knowledge of the subject. ‘Time may supply the 
absent links of our chain, as it has already supplied, and still 
continues to supply many : and, judging from the past, we need 
not despair of finding every deficiency filled up from the daily 
discovered relics of a former world, or the exhaustless recesses 
of the present. 
It has been observed* that, if the natural groups into which 
the animal kingdom is divided bear a uniform analogy to each 
other,—a principle which is among the most important of those 
involved in the system which I wish to illustrate, —it is a necessary 
consequence that their number should be definite. The primary 
groups of those departments of the animal kingdom which have 
hitherto been investigated, have been ascertained to be limited 
to five; and the first great divisions of birds will be found to 
branch out into a similar number. The characters of the types 
of these leading groups are so strongly and distinctively marked, 
that they could not escape the comprehensive eye of Linnæus, 
whose tact in seizing upon the grander affinities of natural ob- 
jects, and bringing them together in their greater groups, has 
left him without a rival among naturalists. Four of his orders, 
which possess such distinctive characters as will not admit of 
their being confounded together, may be at once adopted with 
some slight modification. The powerful and strongly-hooked 
* See “ Remarks on the Identity of certain general Laws," &c. &c. by W. S. Mac- 
Esq. in the present volume of the Transactions, p. 55. 
- j beaks 
