300 SYLVIID^. 



nishes evidence in favour of uniting the Families just named 

 in one, which in that case would bear the name Turdidce, as 

 derived from the oldest genus in it. Indeed it must he ad- 

 mitted that the structural characters on which any distinction 

 between the Thrushes and the Warblers can be maintained 

 are very insignificant, and such as certainly in no other Class 

 of Vertebrates, probably in no other Order of Birds, would 

 be acknowledged sufficient by any zoologist of broad views. 

 But on the contrary it must be allowed that the distinction 

 between these groups is in some measure justified by diffe- 

 rences of habit — though these cannot be easily, if at all, de- 

 fined in technical language ; and, notwithstanding that the 

 argument is eminently unscientific, it may be urged that the 

 separation, recognized almost universally in popular speech, 

 may be defended by its convenience — for, owing to the mul- 

 titude of species known and the many genera which have 

 been founded for their reception, the collection of them into 

 one large Family would produce no small confusion. In- 

 fluenced then by this motive the Editor has determined on here 

 following the plan employed in former editions of this work, 

 and on retaining the separation therein adopted, but it must 

 be understood that he regards this arrangement as dictated 

 entirely by convenience and not to be defended on any other 

 grounds. 



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