vociferating its loud and pleasing note; in doing this, it sits remarkably forward, and appears in constant agitation, continually moving its body up and down with great elegance; now, as it sits so forward, while using this exertion, it would be liable to lose its balance and quit its hold, had it only one toe behind; whereas, by the contrivance of two, it is enabled strongly to adhere to the branch.” The legs and feet of aquatic birds are wonderfully formed for accelerating their motion in that element, which is their greatest security. The bone of the leg is sharp, and vastly compressed sideways: the toes, when the foot is brought forward, close in behind each other in such a manner as to expose a very small surface in front, so that, in the action of swimming, very little velocity is lost in bringing the legs forward; this is very conspicuous in the diver. Some aquatic birds are web-footed before the whole length of the toes, as in the ducks; others only half the length of the toes, like the avoset. Some again have all four toes webbed, as in the cormorant; others whose feet are furnished with a fin-like membrane or each side of the toes; these are either plain, as in the grebe, or lobed, as in the coot and phalarope. There are also some who swim and dive well, whose toes are long and slender, and not furnished with webs or fins, such as the water-hen and rail; but these live as much on land as in water. The gulls and terns, although web-footed, seem incapable of diving; the latter, indeed, we never observed to settle on the water; the former is so buoyant that it floats elegantly on the surface. The avoset, whose feet bespeak it an inhabitant of the water, does not seem to have the power of swimming; the water-ouzel, on the other hand, has not the least appearance of an aquatic, nor can it swim; but it will dive, and remain a long time under water. The serrated claw in the heron and nightjar is a singular structure, which we have not discovered the use of. The bill as well as the feet of birds, makes one of the strong natural divisions; but these are described under the head of each genus. * * * * *