notch is confined to the horny exterior of the beak, no trace of it being to be discovered in the bone, from which, on the contrary, the tooth in the beak of the Falcons is a true process. In other Families, the notch becomes very small, so as at length to be scarcely perceptible; and, in fact, the transition from this Tribe to the Tenuirostres on the one hand, and to the Conirostres on the other, is so gradual that the points of separation cannot be determined with precision.
HEAD OF TYRANNUS.
The food of the birds of this Tribe consists very largely of insects, though not a few combine with this diet, berries and other soft fruits. None of them feed on hard seeds, which constitute the principal support of the Conirostres. With the exception of the single Family of the Finches (Fringilladæ) in the Tribe just mentioned, almost all the birds that possess musical notes are found
