sts between the measures."

This is under date of June 16th. On the following day I made another
entry:--

"The song is, I think, less varied than either the solitary's or the
red-eye's, but it grows more distinct from both as it is longer heard.
Acquaintance will probably make it as characteristic and unmistakable as
any of our four other vireo songs. But I do not withdraw what I said
yesterday about its resemblance to the red-eye's and the solitary's. The
bird seems quite fearless, and keeps much of the time in the lower
branches. In this latter respect his habit is in contrast with that of
the warbling vireo."

On the whole, then, the song of the Philadelphia vireo comes nearest to
the red-eye's, differing from it mainly in tone and inflection rather
than in form. In these two respects it suggests the solitary vireo,
though it never reproduces the indescribably sweet cadence, the real
"dying fall," of that most delightful songster. At the risk of a seeming
contradiction, however, I must mention one curious circumstance. On
going again to Franconia, a year afterwards, and, naturally, keeping my
ears open for _Vireo philadelphicus_, I discovered that I was never for
a moment in doubt when I heard a red-eye; but once, on listening to a
distant solitary,--catching only part of the strain,--I was for a little
quite uncertain whether he might not be the bird for which I was
looking. How this fact is to be explained I am unable to say; it will be
least surprising to those who know most of such matters, and at all
events I think it worth recording as affording a possible clue to some
future observer. The experience, inconsistent as the assertion may
sound, does not in the least alter my opinion that the Philadelphia's
song is practically certain to be confused with the red-eye's rather
than with the solitary's. Upon that point my companions and I were
perfectly agreed while we had the bird before us, and Mr. Brewster's
testimony is abundantly conclusive to the same effect. He was in the
Umbagog forests on a special hunt for Philadelphia vireos (he had
collected specimens there on two previous occasions), and after some
days of fruitless search discovered, almost by accident, that the birds
had all the while been singing close about him, but in every instance
had passed for "nothing but red-eyes."[2]

[2] _Bulletin of the Nuttall Ornithological Club_, vol. v. p. 3.

For the benefit of the lay reader, I ought, perhaps, to