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Show 1870.] MR. J. B. PERRIN ON BALAENOPTERA ROSTRATA. S09 cartilage as to afford a still further protective shield to it. These muscles presented no difference from the very accurate description given of them by Carte and Macalister, except that the internal pterygoid was present, arising posterior and internal to the external pterygoid, and inserted anterior and internal to it, thus closely imitating the disposition of the corresponding muscle in the human subject. It was thin and small comparatively to the external pterygoid. The Pelvic Bones.-These were two in number, both in a cartilaginous condition, situated immediately above and on each side of the anal aperture, the inner extremity of the base of each being distant only an inch and three-quarters from it; they were asymmetrical, the right being a quarter of an inch longer than the left, owing to its anterior extremity being more pointed and prolonged a little more forwards. Both presented two flattened surfaces, two borders (an internal, concave, and an external, convex at its upper and concave at its lower part), and two extremities (an anterior pointed, and a posterior broad and directed obliquely from without downwards and inwards towards the anal aperture). At the summit of the outer convexity there was a small rough fibrous mass, about the size of a pea, in which were imbedded a number of very small cartilaginous plates. This is evidently the rudimentary representative of the femur. It is an easy matter to overlook this little mass, if attention is not particularly directed to it. Both of these cartilaginous pelvic bones were enveloped in a dense fibrous capsule, which, stripped off, exhibited about the middle a prominent pinkish-red spot, studded over with minute puncta vasculosa. In the left one only was there a decided centre of ossification. The right was entirely cartilaginous. Both of these rudimentary pelvic bones were imbedded in a mass of muscular tissue, so that care was required to detect them. The heart and great vessels, except that the former was more median in position and flattened, presented a similar disposition to those of the human subject. The weight of the heart was about 100 oz. The walls of the left ventricle were an inch and a quarter thick, whilst those of the right ventricle were only about half an inch. In the right ventricle there was a very prominent fleshy column, situated on its inner wall, and about half an inch thick. It traversed the long axis of the ventricular cavity. From the middle of this column a second or transverse one arose, which crossed the middle of the cavity to the right wall, where it divided into a number of smaller columns, continuous with those on the posterior wall. The pulmonary artery was very large ; its diameter measured 3^ inches in the interior, readily admitting a circular disk of this size without any distention. Its walls, however, were very thin in comparison with those of the aorta. The pulmonary semilunar valves were large. The right one had a small nodule of Arantius, the rest being destitute of it. The aorta, at its origin from the left ventricle, was two inches in diameter. As it approached the part from which the innominate |
