of "The Architecture of Birds," thus describes its construction from personal observation:—"The interior of these nests is about the form and size of a large breakfast tea-cup, being as uniformly rounded, and, though not polished, almost as smooth. For this little cup the parent-birds lay a massive foundation of moss, chiefly the proliferous and the fern-leafed feather-moss (Hypnum prolierum et H. filicinum), or any other which is sufficiently tufted. As the structure advances, the tufts of moss are brought into a rounded wall by means of grass-stems, wheat-straw, or roots, which are twined with it and with one another up to the brim of the cup, where a thicker band of the same materials is hooped round, like the mouth of a basket. The rounded form of this frame-work is produced by the bird measuring it, at every step of the process, with its body, particularly the part extending from the thigh to the chin; and when any of the straws or other materials will not readily conform to this guage, they are carefully glued into their proper place by means of saliva, a circumstance which may be seen in many parts of the same nest, if carefully examined. When the shell, or frame, as it may be called, is completed in this manner, the bird begins the interior masonry by spreading pellets of horse or cow-dung on the basket-work of moss and straw, beginning at the bottom, which is intended to be the thickest, and proceeding gradually from the central points. This material, however, is too dry to adhere of itself with sufficient firmness to the moss, and on this account it is always laid on with the saliva of the bird as a cement; yet it must require no small patience in
