The few characters assigned to the various groups are sufficiently diagnostic when taken together, although they are not always those upon which the classification has been established: - Class Aves I.
[[Aves Carinatae [L'H]].
[[Aves Ratitae [L'H]].
On muscular anatomy, making the two major divisions of Aves (his Homalogonatae and Anomalogonatae, depend in the first instance on the presence or absence of a peculiar muscular slip in the leg, known as the ambiens, although indeed he expressly stated that this was not on account of the intrinsic importance of the muscle in question, but because of its invariable association with other peculiarities.
It is impossible to reproduce here Fiirbringer's elaborate details and phylogenetic trees with their various horizontal sections, but the following tables give the main outlines: Classis AvEs I.