The eggs of the Fish-Hawk are usually three in number, often only two, and more rarely four. They are subject to great variations as to their ground-color, the number, shade, and distribution of the blotches of secondary coloring with which they are marked, and also as to their size and shape. Their ground-color is most frequently a creamy-white, with a very perceptible tinge of red. This varies, however, from an almost pure shade of cream, without any admixture, to so deep a shade of red that white ceases to be noticeable. Their markings are combinations of an almost endless variation of shades of umber-brown, a light claret-brown, an intermingling of both these shades, with occasional intermixtures of purplish-brown. They vary in length from 2.56 to 2.24 inches, and in breadth from 1.88 to 1.69 inches. It would be impossible to describe with any degree of preciseness the innumerable variations in size, shape, ground-color, or shades of markings, these eggs present. They all have a certain nameless phase of resemblance, and may be readily distinguished from any other eggs except those of their kindred. There are, however, certain shades of wine-colored markings in the eggs of the Fish Hawk of Europe, and also in that of Australia, that I have never noticed in any eggs of the American bird; but that this peculiarity is universal I am not able to say. The smallest egg of the _carolinensis_ measures 2.31 by 1.62 inches; the largest, 2.56 by 1.88. The European egg is smaller than the American, is often, but not always, more spherical, and is less pointed at the smaller end. Among its varieties is one which is quite common, and is very different from any I have ever observed among at least five hundred specimens of the American which I have examined. An Osprey’s egg in my collection, taken near Aarhuus, in Denmark, by Rev. H. B. Tristram, of Castle Eden, England, measures only 2.12 inches in length,—shorter by a fourth of an inch than the smallest American,—in breadth 1.62 inches; its ground-color is a rich cream, with a slight tinge of claret, and it is marked over its whole surface with large blotches of a beautifully deep shade of chocolate. In their habits the European and the American birds seem to present other decided differences. The American is a very social bird, often living in large communities during the breeding-season. The European is found almost invariably in solitary pairs, and frequents fresh water almost exclusively. The American, though found also on large rivers and lakes, is much the most abundant on the sea-shore. The European bird rarely builds on trees, the American almost always. The latter rarely resorts to rocky cliffs to breed, the European almost uniformly do so. There is no instance on record of the American species attacking smaller birds or inferior land animals with intent to feed on them. The European species is said to prey on Ducks and other wild-fowl. GENUS NAUCLERUS, VIGORS.