. Elementary text-book of zoology. Zoology. 23 I AVES. Ent Co of the lower jaw and the maxillo-palatine apparatus are enabled by special articular arrangements to move on the temporal bone and on corresponding processes of the basisphenoid. The quadrate, which i«; articulated to the temporal bone, has, besides the articular surface of the lower jaw, movable connections with the long rod-like quudrato-jugal, and with the usually styliform pterygoid which runs obliquely inwards, while the base of the upper beak presents a thin elastic place below the frontal bone, or is separated from the fronta
. Elementary text-book of zoology. Zoology. 23 I AVES. Ent Co of the lower jaw and the maxillo-palatine apparatus are enabled by special articular arrangements to move on the temporal bone and on corresponding processes of the basisphenoid. The quadrate, which i«; articulated to the temporal bone, has, besides the articular surface of the lower jaw, movable connections with the long rod-like quudrato-jugal, and with the usually styliform pterygoid which runs obliquely inwards, while the base of the upper beak presents a thin elastic place below the frontal bone, or is separated from the frontal bone by a transverse movable suture. When the beak is opened, and the lower jaw is moved downwards, the pressure on the quadrate bone is transferred to the rod-like quadrate-jugal and the pterygoid bones, and from these is transmitted partly directly and partly by means of the palatine bones to the upper beak, so that the latter must be more or less raised at that point. Therefore, when the mouth is opened, the end of the beak is raised. The greater part of the upper beak is formed by the unpaired prajmaxilla, with the sides of which the maxilla? are fused, while an upper median process ascends between the nares and unites with the frontal on the inside of the nasal bones. The hyoid bone (fig. 649) is prolonged into a posterior rod ; its anterior * cornua are usually two-jointed and are not con- nected with the skull, but in some cases they are much elongated and arch over the skull as far as the forehead (Woodpecker). They then consti- tute in connection with the muscles of their sheath a mechanism for the protrusion of the tongue. In the vertebral column (tig. 650), a very long movable cervical region, a rigid dorsal and pelvic region and a rudimentary, only slightly movable caudal region can be distinguished. In Birds there is no separation of thoracic and lumbar regions as in Mammals, since all the dorsal vertebrae bear ribs and the region corresponding with the lumbar r
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
