426 Afr. N. A. Vigors 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. These 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. 

 Tenuii'ostres, Cuv. 



* In 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 whc^le 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 " Hora Entomologica" 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 diflferent 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 structura ma- J DentirostreS. 



gis perfect^ \ Conirostres. 



Aberrant group. r Scansores. 



Rostri pedisque structura mi- ) Tenuirostres. 



nus peifect^ I •»-<• • 



L Fissirostres. 



§ I. Fis- 



