426 Mr. N. A. Vicors on the Natural Affinities 
greater number of forms than are to be found in any of the other 
orders. ‘The families of which it is composed are consequently 
very numerous, and require to be classed in comprehensive sec- 
tions, or, as I shall call them, tribes, which form the primary 
subdivisions of the order. 'lhese tribes may be denominated as 
follows, according to the habits or the modes of structure that 
characterize the birds which compose them : 
* Fissirostres, Cuv. 
Dentirostres, Cuv. 
Conirostres, Cuv. 
Scansores, Auct. 
Tenuirostres, Cuv. 
* Jn enumerating or describing the groups which compose different series of affinities 
returning into themselves, it is of no consequence with which group in the series we begin 
our examination, provided we preserve an uniformity among the whole of our corre- 
sponding series. This consideration, however, should be particularly attended to, for 
the sake of more easily discerning their parallel analogies. It is generally my custom, 
in examining a group, to view it with its more perfect or typical form in the centre, as 
above, and with its less perfect forms on each side. "This mode affords some advan- 
tage, by presenting us at first sight, when we enter upon a group, with that subdivision 
of it which is immediately connected with the group we have quitted. Mr. W.S. Mac- 
Leay in his * Hore Entomologice" has adopted a different, and certainly a more scien- 
tific mode of exhibiting the series of affinities. He divides the whole series into two 
groups, which he calls normal and aberrant; and, commencing with the two subdi- 
visions that form the normal group, he ends with the three that compose the aberrant. 
For the more entire comprehension of my subject, I shall exhibit the different series 
that come before us according to both these methods, adopting that method in the notes 
which has not been followed in the text. The following is the arrangement of the In- 
sessores according to Mr. MacLeay’s plan of exhibiting a series of affinities. 
Normal group. 
Rostri pedisque structurâ ma- { Dentirostres. 
gis perfecta........ Conirostres. 
Aberrant group. Scansores. 
pedisque structura ml- 7. Tenuirostres. 
nus perfectà ....... ES 
Fissirostres. 
§ I. Firs- 
