18/6.] DR. J. V. HAAST ON ZIPHIUS NOV.E-ZEALANDIJE. 469 



Shortly before the septum narium is formed, the premaxillaries 

 coalesce for a short space*. 



The mamillaries, which begin with a narrow point having a down- 

 ward 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 Zipkius 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 pre- 

 maxillaries 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 observ- 

 able, as if they had once served for rudimentary teeth, of which, how- 

 ever, 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 - 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 tower 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 to- 

 wards the 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 072 

 inch. It weighs 184 grains, and runs out at both ends to a con- 

 stricted 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 "I' the prefrontals. 



