VIII INTEODUCTORY. 



reasonably practicable, tbough many others have been taken at second 

 hand, upon the simple principle that even such are better than none at 

 all. Synonyms and references for which I am unwilling to become 

 responsible, are placed between quotation marks; I answer for the rest, 

 being satisfied of their general accuracy, though no one is more fully 

 aware than I am of the typographical difficulties in the way of printing 

 numerous references in which figures are concerned. 



It must not be hastily inferred that these synonymatic lists have no 

 other value than that which attaches to them as bibliographical indices 

 or mere references to the published records. They not only serve as a 

 guide to research, and as vouchers for facts of geographical distribution, 

 but they also have a direct bearing upon the important matter of 

 nomenclature, fixity and precision of which are nowhere more desirable 

 than in the natural sciences, where names become in a great measure 

 the exponents of biological generalizations. A preliminary step required 

 for the establishment of nomenclature upon a firm and enduring basis, 

 is searching scrutiny of the literature of the subject, not only in order 

 to sift out synonyms and to pin down names to the species they repre- 

 sent, but also to ascertain which one, of the number which have been 

 affixed to most species, has the priority which entitles it to recognition 

 and adoption according to the established usages of naturalists. This 

 is a matter which repays the uninviting labor bestowed upon a task 

 otherwise one of little profit and no attractions. The subject has formed 

 a part of my desk-work for several years, and I may congratulate myself 

 that some of the results reached are at length brought to light under 

 very favorable auspices. 



With this matter of nomenclature questions of classification are insep- 

 arably connected in existing methods of zoological notation. As you 

 need not be informed, no leading ornithologists are as yet agreed in 

 detail upon a system of classification ; nor is there any probability that 

 such agreement will soon be brought about. That we are, however, 

 gradually approaching this desirable consummation, is shown by the 

 very general acceptance of many groups established of late years upon 

 investigation of structural characters which were long in receiving the 

 attention their importance demanded, as well as in an equally general 

 admission of a certain sequence of these groups. The questions which 

 remain open have less concern with the definition of groups, excepting 

 some of those among Passeres, than with their value in the taxonomic 

 scale. It has become evident that certain old "orders" of birds cannot 

 endure in the light of recent discoveries ; and that the Baptores, which 

 long headed the system, must give way to the more highly-organized 

 Oscines. It is most probable, according to present indications, that 

 those remarkable extinct forms, the Archwopteryx and Ichthyornis, rep- 

 resent one primary group of Aves (Saururw) ; that the struthious birds 

 constitute another [Batitcc) ; and that all remaining birds compose a 

 third {Carinatce). These divisions may be rated either as subclasses or 



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