OCR Text |
Show 1867.] PROF. HUXLEY ON THE CLASSIFICATION OF BIRDS. 465 The inferior larynx is present, and has one pair of intrinsic muscles. The division of the Gypogeranidee consists of the single genus Gypogeranus, which, though allied to the Falcons in some respects, is so peculiar in others that it must be regarded as the type of a family apart. The feathers have an aftershaft, and the oil-gland a circlet (Nitzsch). The phalanges of the elevated hallux, taken together, are not more than half as long as those of the outer toe. The basal phalanx of the fourth toe is much longer than the distal, and longer than the second and third together. These are subequal and very short, shorter than the fourth phalanx. The basal phalanx of the third toe is much longer than the second, and the second is slightly longer than the third. The shaft of the long tarso-metatarsal bone is prismatic, its anteroposterior diameter being as great as, or greater than, the transverse. The upper part of its posterior face presents a prominent process terminated by an expanded cordate surface, somewhat as in the Cathartidee. The skull has basipterygoid processes, and the spongy maxillo-palatines are completely united, so as to obliterate the intermediate valley. The lachrymal remains distinct; and the long external nares may be pervious, or not, according to the extent of the ossification of the septum. The sternum is escutcheon-shaped, and elongated. The posterior edge is convex, with two small emarginations on each side. There is a distinct manubrial process. The proximal ends of the clavicles are not expanded, and are hardly excavated. A great median process extends from the symphysis of the clavicles, and becomes anchylosed with the sternum. The scapular process of the coracoid is not prolonged to meet the clavicle. In the pelvis nothing is to be seen of that bending of the postacetabular region of the ilium downwards and forwards, which is so strongly marked in most of the other Aetomorphae. 6. The PSITTACOMORPH^E. The rostrum is arched and hooked at the extremity, and is regularly articulated with the frontal region of the skull. Basipterygoid processes are wanting. The palatines are vertically elongated posteriorly, while anteriorly they are horizontally flattened and moveably united with the rostrum. The maxillo-palatines are spongy. The lachrymal and the postorbital bend towards one another and frequently unite below the orbit. The orbital process of the quadrate bone is very small; and its distal end presents only one facet (which is compressed from side to side and convex from before backwards) for the mandible. The rami of the latter are deep, and pass into one another by a rounded truncated symphysis. P R O C ZOOL. Soc-1867, No. XXX. |