the moss and leaves that it deems necessary and made therewith the mass and bulk of the nest, resorts to some little ditch or sluggish stream and trowels up from its margin mud indeed, but not mud alone, for there is amidst it—generally, if not always—a certain proportion of the fibrous roots or rootlets of mud-loving aquatic plants. Of these, the bird can take a firm hold with its bill, and as the mud adheres to the fibrous network, it is enabled to carry a considerable quantity of it at a time, though a greater or less amount often falls off during the passage. It is in this circumstance, as I believe, that one can read the origin of the "extraordinary habit," as Darwin calls it, of a bird's plastering the inside of its nest with mud. It is the thrush to which he alludes, but the description applies equally, and, in respect of the material employed, still more accurately, to the blackbird. At a certain point in its construction, the nest of the latter would be mistaken by anyone without previous experience, for that of a thrush, the cup being as deep and perfect in form and the workmanship not noticeably inferior. It is, however, of a darker colour—black, or approaching to black—though this may vary, according to locality. Over the whole surface are seen the scorings of the bird's beak, which seems to have been used as a trowel. But now, if the nest had been examined a day or two before, its interior, and, especially, the bottom of it, would have been found to be composed of a dank moist mass of vegetation, largely consisting of small water-plants, both the green part and the roots, to the many fibres of which latter a quantity of mud was adhering. Here, then, we read the whole story. Fibrous material was needed on
