As a swimming bird, one that swims with its legs and not with its wings, Hesperornis has probably never been equalled, for the size and appearance of the bones indicate great power, while the bones of the foot were so joined to those of the leg as to turn edgewise as the foot was brought forward and thus to offer the least possible resistance to the water. It is a remarkable fact that the leg bones of Hesperornis are hollow, remarkable because as a rule the bones of aquatic animals are more or less solid, their weight being supported by the water; but those of the great diver were almost as light as if it had dwelt upon the dry land. That it did not dwell there is conclusively shown by its build, and above all by its feet, for the foot of a running bird is modified in quite another way. The bird was probably covered with smooth, soft feathers, something like those of an Apteryx; this we know because Professor Williston found a specimen showing the impression of the skin of the lower part of the leg as well as of the feathers that covered the "thigh" and head. While such a covering seems rather inadequate for a bird of such exclusively aquatic habits as Hesperornis must have been, there seems no getting away from the facts in the case in the shape of Professor Williston's specimen, and we have in the Snake Bird, one of the most aquatic of recent birds, an instance of similarly poor covering. As all know who have seen this bird at home, its feathers shed the water very imperfectly, and after long-continued submersion become saturated, a fact which partly accounts for the habit the bird has of hanging itself out to dry. [Illustration: Fig. 16.--Hesperornis, the Great Toothed Diver. _From a drawing by J. M. Gleeson._] The restoration which Mr. Gleeson has drawn differs radically from any yet made, and is the result of a careful study of the specimen belonging to the United States National Museum. No one can appreciate the peculiarities of Hesperornis and its remarkable departures from other swimming birds who has not seen the skeleton mounted in a swimming attitude. The great length of the legs, their position at the middle of the body, the narrowness of the body back of the hip joint, and the disproportionate length of the outer toe are all brought out in a manner which a picture of the bird squatting upon its haunches fails utterly to show. As for the tail, it is evident from the size and breadth of the bones that something of the kind was present; it is also evident that it was not like that of an ordinary bird, and so it has been drawn with just a suggestion of Archaeopteryx about it.