The class of Vertebrata that features the wild birds
- (ornithology) the class of birds
- The course of Vertebrata that includes the wild birds.
(n. pl.) The course of Vertebrata which includes the wild birds.
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.