(387) as there were plenty pupae left, but found another nest immediately and followed the same procedure with this one. About 5:15 one thrasher went into the brush in front of me and one about 20 feet behind me. The latter began a long under- song . As I did not know which bird was which, I listened intently. It was a very good song, but with few imitations and I decided it was Greenie--rather regretfully--as it would compel me to admit to myself that his song was inferior to Brownie's--at least for the time being. However, when the bird came out to join the other one, it proved to be Brownie, thus, I think, tending to confirm the belief that, over a period of time, there is no fixed, recognisable, constant difference between the songs of these two birds. Tentative Classifica- I do not know whether there is any standard of general recogni- tion for classifying bird songs. My acquaintance with the litera+ ture on the subject--if there is any--is nil. Leaving out calls conversations, alarm notes, etc., it seems to me that I clearly with these two thrashers distinguish four different classes of song. By song I mean something notes that is sustained, not merely a few more or less notes uttered at random without unity, but a continuous musical performance. Whisper song. (Quarter-song) First there is a low, continuous, soft warbling and bubbling song, without mimicry and without distinguishable phrases, i.e. phrases that can be represented to a certain extent--as to vowel sounds and rhythm at least--in syllables, by letters of the alphabet. This song is occasionally punctuated with a few almost insect-like, high-pitched sounds which seem to be forced out as if the bird were holding all of its muscular system in a state of tension. When one of these sounds is heard the bird's throat does not pulsate. With a larger animal it might be a whine or even a squeal. Except for kind of wholly this particular note, the song is pleasing and exceedingly varied. It is an inward song and, I think, can be properly classed with what I hear called a whisper-song. Although I certainly consider