PBINCIPLES AND PBACTICE OF CLASSIFICATION. 79 



species ; as, Turdus migratorius, for the robin. This is the " binomial nomenclature " (badly so 

 called, for "binominal " would be better) ; introduced by Linnaeus in the middle of the last cen- 

 tury. It was a great improvement upon the former method of giving either single arbitrary names 

 to birds, often a mere Latin translation of their vernacular nicknailie, or long descriptive names 

 of several words; probably no other single improvement in a method of nomenclature ever did 

 so much to make the technique of nomenclature systematic. To couple the two terms at all 

 was a great thing, the convenience of which we who never felt its want can hardly appreciate. 

 To follow the generic by the specific term was itself of the same advantage that it is to have 

 the Smiths and Browns of a directory entered under S and B, instead of by Johns and Jameses ; 

 besides according with the genius of the Romance language^ which commonly put the adjec- 

 tive after the noun. A Frenchman, for example, would say, Bec-erois^ aux ailes Blanches de 

 VAmerique septentrionale, or "BOl-crossed to the wings white of the America north/' where 

 we should say, " North American white-winged Cross-bill," and Linnaeus would have written 

 Loxia leviCoptera. The binomial scheme worked so well that it came to have the authority 

 and force of a statute, which few subsequent naturalists have been inclined, and fewer have 

 ventured, to violate; while it became an ex post facto law to prior naturalists, ruling them out 

 of court altogether, as far as the legitimacy of any of the names they had bestowed was con- 

 cerned. It necessarily rested, however, or at any rate proceeded upon, the false idea of a species 

 as a fixity. Linnaeus himself experienced the inadequacy of his system to deal binomially with 

 those lesser groups than species, commonly called " varieties," now better designated as " con- 

 species " or "subspecies"; and he often used a third word, separated however from the 

 binomial name by intervention of the sign " var." or some other symbol. Thus, if he had 

 supposed an American crossbill to be a variety of a European Loxia leucoptera, he might have 

 called it Loxia leucoptera, a, america/na. Some years ago, in treating of this subject, I urged 

 the necessity of recognizing by name a great number of forms of our birds inteimediate between 

 nominal species, and connecting the latter by links so perfect, that our handling of " species" 

 required thorough reconsideration. The dilemma arose, through our very intimate knowl- 

 edge of the climatic and geographical variation of "species," either to discard a great number 

 that had been described, and so ignore aU the ultimate modifications of our bird-forms ; or else 

 to recognize as good species the same large number of forms that we knew shaded into each 

 so completely that no specific character could be assigned. In the original edition of the 

 present work (1872), I compromised the matter by reducing to the rank of varieties the nominal 

 species that were known or believed to intergrade ; and the original edition of the " Check 

 List" (1873) distinguished such by the sign "var." intervening between the specific and the 

 subspeeific name. I subsequently determined to do away with the superfluous term " var.," and 

 in the next edition of the Cheek List (1883) reverted to a purely trinomial system of naming 

 the equivocal forms; as, Loxia curvirostra americana. The same system is used in the present 

 treatise ; it is found to work weE, and seems likely to come into general employ, at least in 

 this country. It is commended to the consideration of our brethren over the sea. 



The Student cannot be too well assured, that no such things as species, in the old 

 sense of the word, exist in nature, any more than have genera or families an actual existence. 

 Indeed they cannot be, if there is any truth in the principles discussed in our earlier paragraphs. 

 Species are simply ulterior modifications, which once were, if they be not stUl, inseparably 

 linked together; and their nominal recognition is a pure convention, like that of a genus. 

 More practically hinges upon the way we regard them than turns upon our establishment of 

 higher groups, simply because upon the way we decide in this case depends the scientific 

 labelling of specimens. If we are speaking of a robin, we do not ordinarily concern ourselves 

 with the family or order it belongs to, but we do require a technical name for constant use. 

 That name is compounded of its genus, species, and variety. No infallible rule can be laid 



