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which numerous woodland species pass. I accounted for the great abundance of such birds at this point by the fact that the whole country to the westward being open, and, therefore, unsuited to their wants, a condensation, or a sort of thickened, folded-over edge of the species here occurred. As long as the migration lasted, the heavy timber of the river-bottom was filled with the birds in a steady stream. There was no occasion to go in search of specimens; stationing myself in some eligible spot, I had only to take them as they came along, fluttering from tree to tree, pursuing insects with a sharp, scraping note, yet never long delaying their onward course. With the second week in June they had all, so far as I know, passed northward; certainly I found no indication of any remaining to breed in this locality.

The species was not observed further west in this latitude, though it has been traced high up the Missouri by other persons. It was named Sylvicola missouriensis in 1858 by Maximilian, the late Prince of Wied.

Length.

Extent.

HELMINTHOPHAGA CELATA, (Say) Bd.

ORANGE CROWNED WARBLER.

Observed during the fall migration, in September, along the Mouse River, where it was abundant.

DENDROCA ESTIVA, (Gm.) Bd.

YELLOW WARBLER.

This abundant and universally diffused species was observed at various points along the whole line, and in the Missouri region.

Not observed until about the middle of September, when, during the fall migration, it made its appearance in abundance along the Mouse River, in company with the Snowbirds and other species just come from the north. It is one of the Warblers which, though distinctively belonging to the Eastern Province, occasionally straggles southward by a direct line from the extreme western points which it reaches in Alaska. Drs. Cooper and Suckley found it in Washington Territory; Dr. Hayden, up the Missouri to above old Fort Pierre; and Mr. C. E. Aiken, Mr. T. M. Trippe, and Mr. H. W. Henshaw have each found it in Colorado Territory. Its breeding-range is not a little remarkable: it has been recorded as breeding in Jamaica, as well as in various parts of British America and Alaska, but is not known to nest in the greater part of the intervening country. Similarly, in winter, some individuals endure the rigors of the Middle, if not of some of the Northern, States, while others press on into Central America. No other Warbler, as far as known, such a peculiar distribution as this.

bas

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DENDROCA AUDUBONI, (Towns.) Bd.

AUDUBON'S WARBLER.

Audubon's Warbler was only observed in the Rocky Mountains, beyond the eastern foothills of which it is not known to extend. From the Rocky Mountains to the Pacific, it is as abundant, in suitable localities, as the Yellow-rump is in most parts of the East, and its counterpart in habits. The individuals found about Chief Mountain Lake did not appear to be migrating,-in fact, the full movement had not begun at the period of observation,-and the species doubtless breeds in this locality. in the heavy pine timber.

Rocky Mountains, Aug. 22, 1874 Elliott Coues...

DENDROCA STRIATA, (Forst.) Bd.

BLACK-POLL WARBLER.

A specimen of this species, procured on Woody Mountain, was observed in the collection made by Mr. G. M. Dawson, geologist of the English Commission.

DENDROCA PENNSYLVANICA, (Linn.) Bd.

CHESTNUT-SIDED WARBLer.

One specimen only of this distinctively Eastern specimen was secured at Pembina,-perhaps its western, if not also nearly its northern, limit. It was not observed beyond the Red River. This is one of the more delicate species of the genus, which regularly breeds little, if any, beyond the Northern States, and entirely withdraws in winter, reaching Central and even South America. I have not found any indication of its occurrence west of the longitude of the Red River in any latitude.

DENDROCA MACULOSA, (Gm.) Bd.

BLACK-AND-YELLOW WARBLER.

Specimen from Woody Mountain, seen in Mr. Dawson's collection.

SIURUS NÆVIUS, (Bodd.) Coues.

WATER THRUSH.

During the progress of the Northwest Boundary Survey, with which the work of the present Commission connected, the Water Thrush was observed in Washington Territory; and since that time its very general range throughout North America has been demonstrated, though the bird was long supposed to be, like S. motacilla, a species of the Eastern Province. A specimen was secured in August west of the Sweetgrass Hills, on the headwaters of Milk River. This was the only individual procured during the expedition, and seemed to be somewhat out of place, since the species frequents, for the most part, moister and better-wooded regions. It was again observed, however, in the undergrowth surrounding some reedy pools near Chief Mountain.

Observed at Pembina, on Turtle Mountain, and in the Rocky Mountains, but not in the open country between these points. The species is one of general distribution in the United States in all suitable localities, and appears to breed indifferently in any latitude within these limits. The Northern Boundary may be not far from the line of its dispersion in this direction.

GEOTHLYPIS PHILADELPHIA, (Wils.) Bd.

MOURNING WARBLER.

I was agreeably surprised to find this species, which is rather rare in most Eastern localities, breeding abundantly at Pembina; and I suspect that the Mississippi Valley, rather than the Atlantic seaboard, may be the principal line of migration along which it comes from its winter home in Central America to its breeding resorts along the northern boundary of the United States. At the end of June I found a nest, supposed to be of this species, but the identification was not at all satisfactory. The birds were breeding in June, as I knew by the different actions of the two sexes. The males were in full song, and, contrary to their very secretive habits during most of the year, became rather conspicuous, not only by their singing, but by their custom of leaving the dense shrubbery and undergrowth, in which they usually hide, to mount to the tops of the trees. The females, on the other hand, were extraordinarily quiet and retiring; so much so, that during the whole month I secured not a single specimen, though nearly a dozen males were taken without much diffi culty. The birds were only observed in the heavy timber of the riverbottom in this locality, and were not afterward encountered during our progress westward; whence I suppose this is about the limit of their Western dispersion. The species appears to breed in like numbers in various portions of Minnesota, where Mr. T. M. Trippe has found it baunting the tamarack swamps and adjoining damp thickets. He corroborates the habit I have just mentioned of ascending to the tree-tops; and, like myself, was unfortunate in finding no nest, though he frequently saw the old birds feeding their young in the latter part of June and early in July. The song is a loud, clear, and agreeable warble, reiterated with great persistency.

GEOTHLYPIS PHILADELPHIA MACGILLIVRAYI, (Aud.) Bd.

MACGILLIVRAY'S WARBLER.

A single specimen was secured in the Rocky Mountains in August. In this latitude at least, the present bird does not appear to approach