The foregoing diagnoses embrace merely the more conspicuous external characters whereby the genera may be most readily distinguished by the student. The following table presents additional accompanying characters afforded by the osteological and anatomical structure, of more importance in defining with precision the several groups embraced in our fauna. =A.= Scapular process of the coracoid produced forward so as to meet the clavicle[42] (HUXLEY). Nasal bones almost completely ossified, the nostril being a small, usually circular opening, with a raised or “rimmed” margin, and conspicuous, usually central, bony tubercle. Inferior surface of the supermaxillary bone with a prominent median angular ridge. Superciliary process of the lachrymal consisting of a single piece. (_Falconinæ._[43]) =B.= Scapular process of the coracoid not produced forward so as to meet the clavicle (HUXLEY). Nasal bones incompletely ossified, the nostrils being very large, and without bony rim or tubercle. Inferior surface of the supramaxillary bone without a median ridge. Superciliary process of the lachrymal variable. (_Accipitrinæ._) _a._ Superciliary process of the lachrymal composed of a single, excessively abbreviated piece;[44] posterior margin of the sternum with a pair of indentations, and without foramina. (_Pandion_ and _Nauclerus_.) _b._ Superciliary process of the lachrymal double, or composed of two pieces, joined by a cartilaginous “hinge,” and reaching nearly across the orbit. Posterior margin of the sternum without indentations, and usually with a pair of foramina. (All except _Pandion_ and _Nauclerus_.) † Septum of the orbits and nostrils incompletely ossified (the former always and the latter usually) and with foramina; posterior margin of the sternum most produced backwards laterally, and incompletely ossified, there being usually a pair of foramina. Intestinal canal short, broad, with the duodenum simple, forming a single loop (MCGILLVRAY). A well-developed “web” between the outer and middle toes. (All but _Haliætus_.) †† Septum of the orbits and nostrils completely ossified, and without any trace of foramina; posterior margin of the sternum produced medially into a convex lobe, and without any trace of foramina. Intestinal canal extremely elongated, attenuated, with the duodenum arranged in several convolutions (MCGILLVRAY). No trace of a web between outer and middle toes. (_Haliætus._) SUBFAMILY FALCONINÆ. GENUS FALCO, AUCT.