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Show 1876.] DR. J. V. HAAST ON ZIPHIUS NOV^E-ZEALANDI^. 469 Shortly before the septum narium is formed, the premaxillaries coalesce for a short space*. The maxillaries, which begin with a narrow point having a downward sloping surface, gradually widen ; and, after having in about the centre of the rostrum a plane surface, the outer side rises to the orbital notch, after which they expand greatly with a deeply concave surface, rising posteriorly to the highest part of the crest, uniting with the frontals through their whole extent. The high maxillary crest of Hyperodon is represented only by a small elevation at the begining of the broad concave surface, similar to that in Ziphius australis, as pointed out by Prof. H . Burmeister in his exhaustive description of that South-American species. A deep and narrow furrow begins on the lower side of both premaxillaries near the point, continuing after their junction with the maxillaries along the latter bones, where it runs below their lateral edge to about the middle of the rostrum, gradually getting shallower and narrower. In these grooves small vascular cavities are observable, as if they had once served for rudimentary teeth, of which, however, not the least remnant could be observed, all without doubt having been absorbed. The vomer begins 5*5 inches from the point of the rostrum between the premaxillaries, forming for 8*76 inches a narrow convex ridge, which in its broadest or central portion is only 0*25 inch broad. The palatal surface of the rostrum is slightly bent upward near the point. The united periotic and tympanic bones are of considerably less size than those of Berardius arnouxi. The tympanic bone is shorter, the anterior end not being so much prolonged and thus resembling more in form the same bone in Hyperodon. The same can be said of the periotic bone, which is also not only shorter, but has the notches between the lobes much shallower than in Berardius. The lower mandible, which projects about 2 inches beyond the point of the rostrum, consists of two thin callous rami, which gradually become narrower till their termination at the point, the bony substance of which they are composed getting more spongy towards tbe begining of the symphysis. From this beginning the united bones curve upwards. At the point two small teeth are imbedded in sockets, the tips rising only a few lines above them. They are covered with rugose cement to the very point, which, in their lower part, forms wartlike prominences. As there is scarcely any difference between the two teeth, I give only the dimensions of one of them, the left one, which is 2*12 inches long, with the greatest breadth about at the centre of 0*72 inch. It weighs 184 grains, and runs out at both ends to a constricted rounded point, that of the apex being the narrowest. It will thus be seen that the weight of this tooth, although it belongs * I give these details, because in another skull of the same species which the Canterbury Museum possesses, and of which I shall give the measurements with some notes below, besides some minor points, a very marked difference occurs in the form of the prefrontals. |
