80 GENERAL ORNITHOLOGY. 
down for determining what shall be held to ~. species, what a conspecies, subspecies, or 
variety. It is a matter of tact and experience, like the appreciation of the value of any other 
group in zodlogy. 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 differentiation 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 literal 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, Twrdus migratorius pro- 
pinquus. 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 
naine: this is the subgenus. When introduced, it always ‘follows the generic term, in par- 
entheses; thus, Zurdus (Hylocichla) mustelinus. This is eumbrous, 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 multiplied 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 
namer referred it. The name of the person who originated the new combination came to be 
generally sutfixed, presumably as the authority for the validity of the classification implied. 
As this was to ignore the proprietorship of the original deseriber, it became customary to 
retain describer’s name in parentheses and add that of the classifier ; thus, Twrdus migratorius 
Linneus ; Planesticus migratorius (Linn.) Bonaparte. The practice still prevails; 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 fully 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 one “albus.” No generic name can be duplicated in zodlogy, 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 our knowledge of 
the structure of birds, and their chronological relations, has progressed. Nevertheless, the 
