Mr. Swainson on several new groups in Ornithology, 161 



Again; so far from a multiplicity of genera creating confusion 

 to the student, there requires but little argument to prove, that 

 when such genera are founded on geographic distribution, the very 

 reverse of this is the case. Let any one take, fo. instance, a 

 Sylvia, the name of which he wishes to ascertain ; as the genus 

 now stands, he will probably have to compare it with 300 separate 

 descriptions, or, in other words, he will have 300 points of reference. 

 We will suppose that the bird inhabits America; the length of the 

 first quill feather immediately betrays its native country, and by 

 the acuteness and slight emargination of the bill he immediately 

 refers it to the genus Syhicola, I have instanced a large group, 

 but even here, instead of reading the characters of three hundred 

 species, the labour would be diminished to that of reading twenty- 

 five or thirty. 



It may excite the surprise of some, and the objections of others, 

 that the number of new divisions here characterized amount to 

 sixty-four ; and that eleven of these contam, at present, only a 

 single species. Yet this astonishment will soon cease on looking 

 further into the matter. The number of species which these 

 genera will comprise, may be estimated, upon a moderate calcu- 

 lation, at 517 : so that there would actually be an average of 

 more than eight to each genus. But this is not all ; for in this 

 estimate I allude only to described or known species. What the 

 proportion may be, when the discoveries of the next ten years are 

 added, it is impossible to guess. Yet this we do know, that when 

 the genus Fsaris was founded, there was but one example, — now 

 there are eight.* Thamnophilus^ in like manner, contained but 

 four or five, — now we know of near twenty-five. While that of 

 Urotomusy proposed but two years ago from a single bird, has now 

 been augmented by three other species. With these striking 

 examples before us, we question whether any naturalist will be 

 hardy enough to revive the old complaint about '' making every 



♦ In this number I include three unpublished species, which will soon be 

 illustrated by Sir William Jardine, Bart, and Mr. Selby. I have now to add 

 another, j\ist received by me from Mexico, which has afforded me great plea- 

 sure, inasmuch as it may probably increase the interest of the forthcoming 

 monograph of this group, preparing by these zealous Ornithologist*. 

 Vol. III. L 



