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



to consider that there are no isolated families, — none but have 

 numerous points of connexion and transition with others ; and to 

 such an extent is this the case, that there is scarcely an extensive 

 family group about the limits of which ornithologists can agree. 

 The Thrushes, Warblers, Flycatchers, Chatterers, Tanagers, 

 Finches, Shrikes, Bush-Shrikes, and many others are in this 

 condition, and offer a striking contrast to the families of the 

 Fissirostres and Scansores, about the limits of every one of which 

 there is scarcely any doubt or disagreement whatever. Here 

 then we have three groups, one of which, though very much 

 more extensive than the others, offers less variation in the form 

 and size of the species, and in the modifications of their prin- 

 cipal organs. Correct principles of classification would surely 

 oblige us to consider the three groups of only equal rank. 



But all the families which compose this group are so inti- 

 mately connected with each other, that the limits of a great 

 many of them cannot be determined, and there is no family of 

 any extent which does not gradually blend into others. How 

 then can we hope to form two or three primary divisions which 

 shall be sufficiently well marked out to command general accept- 

 ance? without some probability of which, the mere multiplication 

 of systems of classification is a nuisance. 



We conceive therefore that the efforts of ornithologists should 

 be directed to the study of the different families individually, in 

 order to determine their extent and to point out their true affi- 

 nities with other families. When this has been done for all, we 

 may be able to arrange the whole group so as to present to the 

 eye a view of the relations of the several parts, and then, and 

 then only, shall we be able to determine whether any and what 

 subdivisions can be established. 



There is one other point on which it is necessary to say a few 

 words before concluding this paper. It is on the connexion of 

 the three groups we have here endeavoured to establish with 

 each other. The subject is a most difficult one, and we have 

 been able to come to no satisfactory conclusion upon it. We are 

 inclined however to imagine, that the Puff Birds and Barbets, as 

 exhibiting the least development of the peculiar characters of 

 their respective tribes, may show the line of connexion between 

 the Fissirostres and Scansores, while the Rollers may connect 

 the former with the normal Passeres somewhere near the Eury- 

 laimidce. But a minute and careful examination of the families 

 in question is requisite to decide so nice a point, on which too 

 the greatest light may be thrown by anatomical observations. 

 It is to be hoped that some ornithologist will be found to inves- 

 tigate it fully. 



