OCR Text |
Show 1867.] PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. 463 The posterior face of the proximal end of the tarso-metatarsus presents two ridges (of which the inner is very much stronger and more prominent than the almost obsolete outer) separated by a deep and wide groove. The skull is broad, and the bones of the brain-case have a spongy diploe. Basipterygoid processes are always present, and the tumid and spongy maxillo-palatines are separated by an interval, which may be wide throughout, or reduced to a cleft below. The peculiarly spongy lachrymal remains distinct for a long time, if not throughout life, from the frontal bones and the prefrontal processes. The external nares may be long, but are never pervious, the septum being well ossified. The sternum is commonly four-notched, and has a manubrial process. The proximal ends of the clavicles are comparatively little expanded or recurved, and become very slender towards their symphysis. The clavicular process of the coracoid fits into an excavation on the outer surface of the clavicle. The scapular process of the coracoid is prolonged forwards to meet the clavicle. The lower larynx possesses one pair of intrinsic muscles. The Cathartidee comprise the Vultures of the New World (Cathartes and Sarcoramphus) *. The feathers have no aftershaft, and the oil-gland wants the circlet of feathers. The phalanges of the hallux, taken together, are about half as long as those of the outer toe, and the articular surface of its short metatarsal lies above the level of the articular faces of the other metatarsals; the claws are blunt and comparatively straight, and the fourth toe is not reversible. The second and third phalanges of the fourth toe, taken together, are as long as, or longer than, the basal phalanx. The basal phalanx of the third toe is longer than either the second or the penultimate, the two latter being subequal. The tarso-metatarsus is thick, and its inner edge rounded and not much thinner than the other. The posterior face of the proximal end of the bone presents a broad and prominent process, with a truncated posterior surface. This surface has the contour of a heart with its apex downwards, and is divided by a low longitudinal ridge into two slightly excavated surfaces, of which the outer is the smaller. Below, the process passes into a ridge, which runs down upon the middle metatarsal. The skull is provided with basipterygoid processes, and has an elongated rostrum. The valley between the lamellar maxillo-palatines is both deep and. wide. The lachrymal bones are so completely anchylosed with the frontals and with the broad prefrontal processes, that all traces of their primitive distinctness are completely lost. * I have examined skeletons of Cathartes foetens, C. aura, and C. californianus, of Sarcorhamphus gryphus and S. papa, and compared them with species of Neophron, Vultur, Gyps, Gypohierax, and Gypaetus. |