IN A recent number of 'The Auk,' Dr. Stone' has ably discussed the subspecies question, bringing the various ideas that have been expressed on the subject up to date. For some years I had been entertaining a number of ideas concerning the relationships of species and subspecies. Dr. Stone's paper served to clarify these ideas, and I am presenting them here. It has been generally considered that the museum ornithologist with large series of skins to study, is the final authority on all questions as to what are species and subspecies. The field ornithologist, that is, the student of living birds in their natural environments, is not supposed to have anything to say about it. But the facts are that the moment a bird is dead it has lost a large number of the characters of the species to which it belongs. Its characteristic habits and actions, its call-notes, alarm-notes, songs, the habitat it selects in which to breed, the type of nest its instinct prompts it to build, and the kind of place in which its nest is located are all just as much characters of the species as are the coloration of its feathers and the length of its wing or tarsus. When two species in the same genus differ only slightly in coloration, but widely in these field characters, the degree of difference seems, to the field man, much greater than it does to the museum man. Conversely, when species do not differ in these field characters, even though their plumages are quite distinct, there is reason to think that the degree of difference is really less than the museum man is likely to make it. Many years ago Coues,2 discussing the Eastern and Western Wood Pewees, wrote, We may have to acknowledge, in some cases, that species are better determined in the field than in the closet. If this be true in any case, it holds with the little flycatchers. I should hesitate to identify the Least and Alder Flycatchers in the field by sight alone. I should have greater certainty in separating two such subspecies as the Prairie and Northern Horned Larks. This agrees with Dr. Stone's statement that subspecies . . . are as easy to identify in the field as are many species (p. 37). But if, in either case, the bird in question produced some sound, the Flycatcher would be immediately identified beyond question, but the Larks could not be separated by that means. If we find these two Flycatchers nesting on their breeding grounds, the