The bone of the ear in the Bakelite differs from that of the Dolphins in the enormous thickness of the tympanic bone, especially on the internal side. The tympanic bet) is a little more closed in front, but leaves between it and the petrous bona on the internal aide a solution of continuity wider and longer in proportion. It is not bilobated backwards. The petrous bone is of very irregular form, and very rugged; it gives off two great and stout apophyses, also very rugged, one of which, posterior and a little superior, articulated to a corresponding apophysis of the tympanic bone, is inserted between the temporal and lateral occipital; and the other, anterior and inferior, is articulated by agnomens suture with the temporal portion, which descends to furnish articulation with the lower jaw. The ear-bones in all the Cetaceans are four in number, as in the Hamiaalia, and the malleus is anchylosed to the frame of the tym panum, which, Cuvier observes, is the more singular, inasmuch as it is not deprived of its muscles.
Cuvier remark', that the aka of the Greenland Whale differs more from the of the Cape than the skulls of the ltorquala differ from each other. lie points out these differences, which extend, although slightly, to the bones of the oar ; and expresses his opinion that they are different species.
In the great Cape Baleen, according to Cuvier, the atlas, the axis, and the five other cervical vertebras are united together by their joction externally : there are only three in the second. The metatar sals are in length only double their width. The thumb has two phalanges, the ring-finger four, the little finger three; and all are terminated by a cartilaginous dilatation. A wide and short fin obliquely rounded is the result. (' Ossemens Fossiles.') The Niels in the Cetaceans ia, as we have seen, only rudimentary ; but it may be necessary here to give a summary of the modification of the bones and their connection with the skeleton in the different groups.
In the Dugong it consists of two pairs of bones joined two and two, and end to end, by a cartilage: to the retebras this apparatus is attached by a cartilage also.
The construction of this part varies in the true Zoophegoue Cetaceans. Two small long bones lodged in the flesh, one on each side of the anus, form the pelvic rudiments in the Dolphins. In the great whales, the Mystiecte, or Whalebone Whale, for example, at the extremity of each of the bOnes, regarded by comparative anatomists ilia, a second, which is smaller and curved, is articulated. The con
vexity of this last bone is external, and may be considered as a pubis or isehium.
bodies. All their spinous apophyses are anchylosed into a single crest The atlas and axis unite besides by their upper transverse apophysee, which are wide and strong : their lower transverse apophyses, which are equally long and strong, are anchylosed to each other and to that of the third, which is more slender. The next four cervicale have only delicate transverse apophyses, of which the third, fourth, and fifth are anchylosed together. The last also has only one upper transverse apophyais, but longer, stronger, free, and directed forwards. Cuvier remarks that this division of the apophyses into upper and lower responds to the two branches separated by a canal, which are seen in those of ordinary mammals. The transverse apophyses of the first dorsal are directed also forwards, and are long and a little stronger than at the last cervical ; they commence increasing in bulk, rind shortening at the fourth dorsal. The succeeding take a more transverse direction, and ere enlarged at the end, to the tenth inclusive. Counting from the eleventh, they again begin to elongate to the seventeenth; they then diminish insensibly to the thirty-fourth, where they disappear. They are throughout longer than in the 'Cachalot, and enlarged towards the end, the contrary of which is manifested in that genus. There are fifteen pairs of ribs ; the last four pairs and the first two do not reach the body of the vertebra, and are only attached to its transverse apophyais. The first pair is flattened and extremely wide, especially at the sternal extremity. The last three are slender and short. After the fifteen dorsal vertebra come twenty-seven others. The V-ahapeel bones commence between the eleventh and twelfth ; they are small compared with those of the Cnehalot, and disappear after the twenty-sixth. The eleven or twelve Inset vertebra have no longer aoy eminences. The lost of all are nearly quadrangular, and are each pierced with two vertical holes. The spinous epophyses form a tolerably uniform series of moderate height, all inclined forwards; they begin to diminish on the tail. The anterior articular apophyses are not elevated, remain at the same height, and preserve the same dimeneione. They widen on the tail where they have no articulation to furnish, and the last five or six, nearly equal to the corresponding spinous apophyses, form with them on their vertebrae a trilobated prominence.