. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 572 CETACEA. ble or triple ridges, and with the root distinct from the crown, pre- senting a remarkable resemblance to those of some of the Pachy- derms, as the Hippopotamus. The Dugongs have simple elliptical molares, the crown of which, before it is worn, presents two slight fur- rows, which are entirely effaced by age. They are without fangs, properly so called; and in the up- per jaw are found two long tusks, of which the other Cetaceans of this family are destitute. The Rytince have no molares at all; these teeth ar
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 572 CETACEA. ble or triple ridges, and with the root distinct from the crown, pre- senting a remarkable resemblance to those of some of the Pachy- derms, as the Hippopotamus. The Dugongs have simple elliptical molares, the crown of which, before it is worn, presents two slight fur- rows, which are entirely effaced by age. They are without fangs, properly so called; and in the up- per jaw are found two long tusks, of which the other Cetaceans of this family are destitute. The Rytince have no molares at all; these teeth are replaced by a horny plate in the middle of each jaw, a structure which seems to connect these animals with the Whalebone Whales. The tongue is short and but little susceptible of movement. The os hyoides is characterized in the Cetacea chiefly by the slight degree or total absence of connection with the larynx, resulting from the elevated position of this organ required by its peculiar relations with the posterior nares. In the Herbivorous order the Dugong pre- sents a simple form of the os hyoides; the posterior cornua soon anchylose with the body, but send no ligament to the thyroid cartilage. The anterior cornua generally remain cartila- ginous, and form the medium of union be- tween the body or basi-hyal, and the large and long styloid processes. In the Delphinidis the body and posterior cornua of the hyoid bone are of a flattened form. In the Balenidie, as the Piked Whale or Baloenoptera, the body (a, Jig. 258) is a cylindrical bone, extended Fig. 258. Fig. Tongue and Baleen-plates of the Piked Whale, Balcenoptera Boops.* The genio-glossi pass backwards and inwards from the anterior contour of the lower jaw. The tongue itself corresponds to the form of the space included by the rami of the lower jaw, and is consequently of great size in the Cachalots and Balaenidae, rising in the latter like an immense cushion (a, Jig. 259), into the space between the laminse of b
Size: 2352px × 1063px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, booksubjectanatomy, booksubjectphysiology, booksubjectzoology
