Keel (bird anatomy) keel; and ratites (from "ratis", "raft" — referring to the flatness of the sternum), having a subtle keel structure or lacking one entirely. However, this classification has fallen into disuse as evolutionary studies have shown that many flightless birds have evolved from flighted birds. The current definition of Carinatae now includes all extant birds. Keel (bird anatomy) A keel or carina (plural carinae) in bird anatomy is an extension of the sternum (breastbone) which runs axially along the midline of the sternum and extends outward, perpendicular to the plane of the ribs. The keel provides an anchor to which a
The Anatomy of Melancholy melancholia (which includes, although it is not limited to, what is now termed clinical depression). Although presented as a medical text, "The Anatomy of Melancholy" is as much a "sui generis" work of literature as it is a scientific or philosophical text, and Burton addresses far more than his stated subject. In fact, the "Anatomy" uses melancholy as the lens through which all human emotion and thought may be scrutinized, and virtually the entire contents of a 17th-century library are marshalled into service of this goal. It is encyclopedic in its range and reference. In his satirical preface to the