80 GENERAL ORNITHOLOGY. 



down for determining what shall be held to be a species, what a conspecies, subspecies, or 

 variety. It is a matter of tact and experience, like tlie appreciation of the value of any other 

 group in zoology. There is, however, a convention upon the subject, which the present 

 workers in ornithology in this country find available ; at any rate, we have no better rule to go 

 by. We treat as "specific" any form, however little different from the next, that we do not 

 know or believe to intergrade with that next one ; between which and the next one no inter- 

 mediate equivocal specimens are forthcoming, and none, consequently, are supposed to exist. 

 This is to imply that the diftereutiation is accomplished, the links are lost, and the characters 

 actually become "specific." We treat as "varietal" of each other any forms, however differ- 

 ent in their extreme manifestation, which we know to intergrade, having the intermediate 

 specimens before us, or which we believe with any good reason do intergrade. If the links 

 still exist, the differentiation is still incomplete, and the characters are not specific, but only 

 varietal, in the Uteral sense of these terms. In the latter case, the oldest name is retained as 

 the specific one, and to it is appended the varietal designation : as, Turdiis migratorius pro- 

 jjinquus. The specific and subspecific names are preferably written with a small initial 

 letter, even when derived from a person or place. 



One other term than those just considered sometimes forms part of a bird's scientific 

 name : this is the subgenus. When introduced, it always follows the generic term, in par- 

 entheses; thus, Turdus {Hylodchlci) mustelinus. This is cumbrous, especially when there 

 are already three terms, and is little used in this country. I have latterly discarded it altogether. 

 There is no real difference between a subgenus and a genus, — it is a difference of slight 

 degree merely ; and modern genera have so multiphed that one can easily find a single name 

 for any generic refinement he may wish to indulge. 



It has always been customary to write after the bird's name the name of the original 

 describer of the species, — originally and properly, as the authority or voucher for the validity 

 of the species named. But as genera multiplied, it was often found necessary to change the 

 generic name, the species being placed in another genus than that to which its original 

 nanier refeiTed it. The name of the person who originated the new combination came to be 

 ircuerally suffixed, presumably as the authority for the vahdity of the classification impUed. 

 As this was to ignore the proprietorship of the original describer, it became customary to 

 retain describer's name in parentheses and add that of the classifier ; thus, Turdus migratorius 

 Linnaeus ; Planesticus migratorius (Linn.) Bonaparte. The practice still prevails j it is no 

 more objectionable than any other harmless exhibition of human vanity. The student will find 

 it carefully carried out in my Check List, and entirely discarded in the present work. 



It would take me too far to go fuUy into the rules of nomenclature : some few points may 

 be noted. A proper sense of justice to the describers of new genera, species, and varieties, 

 prompts us to preserve inviolate the names they see fit to bestow, with certain salutary 

 provisions. Hence arises the " law of priority." The first name given since 1758 is to be 

 retained and used, if it can be identified with reasonable certitude ; that is, if we think we 

 know what the giver meant by it. But it is to be discarded, and the next name in priority of 

 time substituted, if it is "glaringly false or of express absurdity," — as calling an American bird 

 " africanus," or a black oue " albus.^' No generic name can be duplicated in zoology, and one 

 once void for any reason cannot be revived and used in any connection. The same specific 

 name cannot be used twice in the same genus. 



The Actual Classification of Birds has undergone radical modification of late years, 



though the same machinery is employed for its expression. This is as would be expected, 

 seeing how profoundly the theory of Evolution has affected our principles of classification, how 

 completely the morphological has replaced other systems, and how steadily om- knowledge of 

 the structure of birds, and their chronological relations, has progressed. Nevertheless, the 



