The shoulder-blade, as in the Manatee, has its anterior angle rounded, the posterior angle sharp, and carried well backwards ; the posterior border very oblique and slightly concave. Its spine is pro jecting, its acromion pointed, but much less elongated than in the Manatee. The corticoid process is much more pointed than in that animal, and directed forwards and a little inwards. The humerus is much stouter and shorter than in the Manatee ; its deltoid crest pro jects more, and it forms with the great tuberosity a rhomboidal pro tuberance. The bones of the fore-arm are rather longer in proportion than those of the Manatee, but their form is the same, and they are equally conjoined at their two extremities. There are only four carpal bones ; two of which are in the first row, one for the radius, the other for the ulna ; and two in the second, the first of which supports the metacarpals of the thumb and fore finger, and the second those of the middle and ring-finger. That of the little finger bears upon the second bone of the second row, and upon that of the first. The thumb, as in the Manatee, is reduced to a pointed metacarpal. The other fingers have the ordinary number of phalanges, the last of which are compressed and obtuse. (` Ossemens Fossiles.') Professor Owen, in his 'Anatomy of the Dugong' (` Zool. Proc.,' 1838), remarks that after the excellent and elaborate descriptions of the osteology of that animal by Cuvier, Riippell, and others, but little remains to be said on the subject. The bones, Professor Owen observes, are chiefly remarkable, as in the Manatee, for their dense texture and the non-development of medullary cavities in them. This reptile-like condition of the skeleton is, he adds, further exempli fied in the loose connection of the bones of the head. The bones are not loaded with oil as in the true Cetacea. All the specimens ex amined by the Professor presented 7 cervical and 19 costal vertebra, corresponding to the 19 pairs of ribs ; but the number of the remaining vertebra exceeded that ascribed to the Dugong by Home and Cuvier, there being at least 30, making in all 55. ltiippell assigns to the Halicore tabernacuti 7 cervical, 19 dorsal, 3 lumbar, 3 pelvic, and 27 caudal vertebra); in all 59. Professor Owen found, as Riippell also describes, that the first four pairs of ribs reached the sternum through the medium of cartilages ; all the others terminated freely in the mass of abdominal muscles : the tenth to the fifteenth Professor Owen found the longest, and the last the shortest.
The Professor points out that the affinity of the Dugong to the Pachydermata is here again illustrated by the great number of the ribs. The lower jaw is, he observes, articulated to the cranium by a true synovial capsule, reflected over cartilaginous surfaces, and not, as in the Carnivorous Cetacea, by a coarse and oily ligamentous sub stance. In treating of the rudimental pelvic bones of the Dugong, he remarks that in the true Cetacea the parts analogous to the ischia are alone present, and that those bones serve a similar purpose in the Dugong.
height corresponding with the curvature and length of the intermaxil lary bones. This part shows in the adult the remains of three or four alveoli on each side.
The atlas is very similar to that of the Manatee ; the axis the same.
The five other cervical vertebra are very delicate, but not conjoined. There are 18 dorsal vertebra, the vinous apophyses of which are arranged nearly in a straight line. Counting from the ninth, the ribs do not attach their bead between two vertebra, but only to the same vertebra, to the transverse apophysis of which they arc articulated. The ribs are not nearly so stout as in the Manatee, but, notwithstanding, the first are still very thick and have their edges blunt. After the 18 dorsal vertebrae come 27, and perhaps more, whose vinous apo physes diminish progressively. In the lumbar vertebra the transverse apophyses are very long ; afterwards they diminish by degrees on the sides of the tail, and again become rather longer at its extremity, apparently for the support of the tail-fin. It would seem that the first three enlk belong to the loins. The fourth has towards its extre mity a facet, which is probably destined for the attachment of the pelvic bones, which last are well marked in the Dugong. They are Zoophagous Cetaceans.—The skull in the Dolphins is very much elevated, very short and very convex behind. The occipital crest sur rounds the top of the head, and descends on each side on the middle of the temporal crests, which are directed much more backward than it is. This large and occipital surface is formed by the occipital, the interparietal, and parietal bones, which early unite into one piece. The parietal bones descend on each side into the temple betweeu the temporal and the frontal bones, and they there reach the posterior sphenoid bone. In frout and above, the parietals terminate behind the occipital crest, and the maxillaries approaching on their aide, what appears of the occipital bone externally only represents a very narrow band, which traverses the skull from right to left, and seems to dilate at each extremity to form the wall of each orbit ; but on raising the maxillary and nearly the whole of the anterior surface of the cranium, the frontal bone will show itself much larger than it appears to be externally. The nasal bones are two rounded tubercles let into two fossa of the middle of the frontal, and in front of which the nostrils are sunk vertically. The posterior and vertical surface of these nos trils is formed by the cribriform plate of the ethmoid bone, but it has very few holes—three or four, sometimes leas. The rest of the inter nal contour of the nostrils belong* to the maxillaries. Their septum is the vomer, which is united to the ethmoid bone as ordinarily. The maxilla:lies, after forming the long muzzle, and arriving in the neigh bourhood of the orbits, enlarge, and cover with a wide and dilated band the ceiling which the frontal bone gives to those cavities, and the whole anterior surface of the frontal bone, with the exception of the small band, which they suffer to appear along the occipital crest. They also touch the bones of the nose. The two intermaxillaries form the external and anterior border of the nasal aperture, and descend upon and between the two maxillaries up to the point of the muzzle, where they even show themselves below ; but the maxillaries are seen a little between them, above, near the nostrils.