"It is wonderful," continues Dr. Jenner, "to see the extraordinary exertions of the young Cuckoo when it is two or three days old, if a bird be put into the nest with it that is too weighty for it to lift out. In this state it seems ever restless and uneasy; but this disposition for throwing out its companions seems to decline from that time till it is about twelve days old, when, as far as I have seen, it ceases entirely. Indeed, the disposition for throwing out eggs appears to cease a few days sooner, for I have frequently seen the young Cuckoo, after it had been hatched nine or ten days, remove a nestling that had been placed in the nest with it, while it suffered an egg, put there at the same time, to remain unmolested. The singularity of its shape is well adapted to these purposes, for, unlike other newly-hatched birds, its back, from the shoulders downwards, is very broad, with a considerable depression in the middle. This depression seems formed by Nature for the design of giving a more secure lodgment to an egg or a young bird, when the Cuckoo is employed in removing either of them from the nest. When it is twelve days old, this cavity is quite filled up, and then the back assumes the shape of nestling birds in general." * * * * * The JAY CUCKOOS (_Coccystes_) are recognisable by their elongate body; thick, broad, curved beak, which is compressed at its sides and almost equals the head in length; strong and comparatively long and partially-feathered feet; moderate-sized wing, in which the fourth quill is the longest; and long, conical tail, composed of narrow feathers, the outermost of which are only half the length of those in the centre. The smooth plumage takes the form of a crest upon the head, and is similarly coloured in both sexes. This group is almost peculiar to the African continent. THE JAY CUCKOO. The JAY CUCKOO (_Coccystes glandarius_) is deep grey on the head, greyish brown on the back, and greyish white on the under side. The throat and upper breast are reddish yellow; and the feathers on the wing-covers and the secondary quills have broad, triangular, white spots at their tips; the eye is deep brown, the beak purplish grey, and the foot greyish green. This species is about fifteen inches long; the wing measures eight, and the tail eight and a half inches.