. The comparative anatomy of the domesticated animals. Veterinary anatomy. TEE FGETU8. 913. which advance towards each other, though they remain a long time apart; so that at this time the young animal really has a hare-lip. The second jiharyngeal arch forms the stapes, the pyramidal process of the temporal bone, styloid arch, and branch of the hyoid. The Fig- 439. tliird develops the hyoid with its cornua; while the fourth arch only constitutes the soft parts of the neck. C. Development of the Thorax.—The ribs are de- pendencies of the proto- vertebral laminas, which ciu've towards the lower
. The comparative anatomy of the domesticated animals. Veterinary anatomy. TEE FGETU8. 913. which advance towards each other, though they remain a long time apart; so that at this time the young animal really has a hare-lip. The second jiharyngeal arch forms the stapes, the pyramidal process of the temporal bone, styloid arch, and branch of the hyoid. The Fig- 439. tliird develops the hyoid with its cornua; while the fourth arch only constitutes the soft parts of the neck. C. Development of the Thorax.—The ribs are de- pendencies of the proto- vertebral laminas, which ciu've towards the lower face of the vertebral column. The true ribs are most rapidly developed, and before attaining the middle line are united by their internal extremity, and form a moiety of the ster- nimi. A fissure separates the costal arches of the right side from those of the left; this gradually contracts, and finally dis- appears, and the sternum is then formed. The ribs are, after the petrous bone, the parts of the skeleton which are most promptly ossified, ossification commencing in the middle ribs. The costal arches do not belong exclusively to the dorsal vertebrte, but have a tendency to form along the whole length of the spine; and it is not rare to see, attached to the lumbar vertebrje, a small cartilaginous nucleus which is soon lost in the texture of the abdominal walls. This nucleus assumes large dimensions on the last cervical vertebrfe of birds. The form of the thorax varies with the species; in some it is circular, in others it is flattened laterally; and in all cases it is less developed in the foetus and young animal than in the adult. It is in the latter that the thoracic cavity presents, proportionately, its greatest dimensions. D. Development of the Limbs.—The limbs do not show themselves until after the formation of the spinal coliunn, the pharyngeal arches, and the thoracic parietes. They appear as four little prolongations from the thorax and pelvis, and are slightly e
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