There are two nests of Sennett's warbler in the Thayer collection in Cambridge. One of these was taken for F. B. Armstrong in Tamaulipas, Mexico, on July 5, 1911, and held three eggs. It is described as a "nest of hair in bunch of growing moss hanging from limb of cypress tree in river bottom," 8 feet up; it is built right into the _Tillandsia_ and is made almost wholly of black and white cattle hair. The other, with a set of four eggs, was taken by James Johnson near Saltillo, Mexico, on May 27, 1906. It is described by the collector as "dug and hollowed in a bunch of pipestem mosses." It is a compact little nest made of very fine rootlets, very fine grasses, shreds of the brown inner bark of the palmetto or palm, and some weed blossoms; it is lined with finer shreds, a little plant down, and a few feathers. Externally it measures 2-1/2 inches in diameter and 2 inches in height; the inside diameter is about 1-1/2 inches; and the depth of the cup about 1-1/4 inches. _Eggs._--Either 3 or 4 eggs seem to constitute the full set, as far as we now know, for Sennett's warbler. The 7 eggs in the Thayer collection vary from ovate to short ovate, and have only a slight lustre. They are white or creamy white and are speckled and spotted with shades of "wood brown," "cinnamon-brown," or "Brussels brown," with underlying spots of "pale brownish drab." On some eggs the markings run to much darker browns, such as "auburn" and "chestnut," and on these the drab spottings are frequently lacking. Usually a loose wreath is formed where the spots are concentrated at the large end, but occasionally they are distributed nearly evenly over the entire surface. The measurements of 36 eggs average 16.3 by 12.2 millimeters; the eggs showing the four extremes measure =19.0= by =13.7= and =15.0= by =11.3= millimeters (Harris). _Plumages._--Young Sennett's warblers that I have examined are uniform grayish olive above, inclining to olive-green on the back; the black lores and cheeks are lacking; the median wing coverts are narrowly tipped with whitish, and the greater coverts more broadly so; the chin is pale yellow; the chest and upper breast are shaded with pale gray and centrally tinged yellowish; the abdomen is dull white; and the sides and flanks are shaded with pale olive-grayish. I have not seen enough material to trace subsequent molts and plumages, which doubtless parallel those of the parula warbler. _Food._--We have no definite information about the food of Sennett's warbler, but Clarence F. Smith has sent me the following note: "The only laboratory report available on the food of the species pertains specifically to a South American subspecies of the _pitiayumi_ group. The stomach contents were reported to consist of remains of hymenopterous insects and two-winged flies (Zotta, 1932)." * * *