. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Skull of the Dugong. (d,d),are consequently proportionally shorter than in the Manatee. The processes of the frontal bone, which form the superior boundary of the orbits, are thinner and more rugose in the Dugong; the portion of the superior max- illary bone, which serves as the floor of the orbit, is narrower; the malar bone (e, e, Jigs. 246, 247), which forms by its curvature the anterior and inferior margins of the orbit, is more compressed and descends lower down. The lachrymal bone, which is situated at the anterior
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Skull of the Dugong. (d,d),are consequently proportionally shorter than in the Manatee. The processes of the frontal bone, which form the superior boundary of the orbits, are thinner and more rugose in the Dugong; the portion of the superior max- illary bone, which serves as the floor of the orbit, is narrower; the malar bone (e, e, Jigs. 246, 247), which forms by its curvature the anterior and inferior margins of the orbit, is more compressed and descends lower down. The lachrymal bone, which is situated at the anterior angle of the orbit (f,fg. 246), is of larger relative size than in the Manatee; but, as in that species, it is imperforate. The zygo- matic process of the temporal bone (g, Jigs. 246, 247), which, in the Manatee, is propor- tionally thicker than in any other animal, is of more ordinary dimensions in the Dugong, being more compressed, and extended further back- wards. The connexions of the bones of the cranium are the same in both these herbivorous species. The parietal bones (h,Jig. 247) are developed in the foetus, as usual, each from a distinct centre of ossification ; but, what is very remarkable, the ossification of the inter- parietal bone also proceeds from two lateral and symmetrical points: these four, originally distinct bones, are, however, very early anchy- losed together, and-also to the superior occipi- tal bone, which latter junction takes place be- fore the three other elements of the occipital bone have coalesced. The parietal cristae are widely separated from each other. The occiput is narrower, and its crest is less marked than in the Manatee. In the interior of the cranium we may observe that there is no bony tento- rium, and that the cribriform plate of the ethmoid is reduced to two simple depressions, widely separated from one another, and termi- nating anteriorly in two or three small foramina. There is no sella turcica for the pituitary gland. The optic
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