Mr. A. R. Wallace on the Natural Arrangement of Birds. 207 



Then take a dozen pieces of paper or card cut out with a gun- 

 wadding punch, and on each write a name of a genus. Place them 

 on a table and arrange them according to your list. This will 

 not always be so easy a matter as it appears at first sight, for 

 you will most likely find that you have set down some conflicting 

 affinities, or that you have mistaken some mere analogies for 

 affinities. When you have them in tolerable order, the next 

 thing is to get the distances between them to bear some propor- 

 tion to the closeness or remoteness of the affinities, and lastly, 

 bring the whole into symmetry by placing what appears to be 

 the main line of affinities in a straight line, and bringing the 

 others into branches right or left from it. When this is done, 

 the positions can be copied on a sheet of paper and kept for 

 reference as a trial-arrangement, which is to be tested by every 

 new fact that is procured, and by any additional knowledge that 

 may be gained on the structure or habits of any of the species. 

 The advantage claimed for this particular form of .diagram is 

 that it can be printed with ordinary type, whereas any circles or 

 figures to represent the groups require woodcuts or lithographs. 

 It is much to be wished that in every systematic work each tribe 

 and family should be illustrated by some such diagram, without 

 which it is often impossible to tell w^hether two families follow 

 each other because the author thinks them allied, or merely be- 

 cause the exigencies of a consecutive series compel him so to 

 place them. Thus, Bonaparte places in his ' Conspectus,^ the 

 Trochilida between the Cypselidce and the Phytotomidce. By 

 making them follow the Swifts he would seem to take the same 

 view of their affinities as is here done, but by placing imme- 

 diately after them the Phytotomidce, one is at a loss to understand 

 by what principles he has been guided. An explanatory dia- 

 gram, or even the plan of denoting the affinities as adopted by 

 Ur. Lindley, would remove such doubts, and render a work of 

 such great labour and research as the one referred to less likely 

 to be misunderstood. 



On the Affinities and Limits of the Scansorial Birds. 



However much systematists have diff'ered as to what families 

 should enter into or be excluded from the Scansores or Climbers, 

 considered as a natural group of Birds, there are four families 

 which have formed ])art of it in every system. These are the 

 Woodpeckers [Picidce), the Parrots {Psittacida), the Cuckoos 

 {Cuculifke), and the Toucans {lihamphastidce) , We may there- 

 fore take these as a basis, to inquire in what respects the Scan- 

 sores differ from the true Passcres and from the Fissirostres, and 

 to deduce their natural characters. Having done this, we may 



