524 DR. J. E. GRAY ON CETACEA [June 27, 
Proc. Zool. Suc. 1865, p. 358), proves on examination to be a very 
distinct species of the genus, allied to Z. micropterus, as I decided 
from the notes and drawing. The peculiar form of the teeth, which 
are elongated and arched over the outer surface of the upper jaw, so 
as to prevent the animal from opening its mouth beyond a very 
limited extent, it has been suggested to me, may be only an indi- 
vidual peculiarity or malformation. I scarcely think this is the case ; 
but even if it should be, it will not in the least militate against the 
distinctness of the species, as the proportion of the beak to the size 
of the brain-case, and the form of the beak and position and form of 
the teeth, with a small point near the tip, are sufficient to clearly 
characterize the species. 
The front edges of the lower teeth are absorbed or worn away by 
the friction of the upper jaw against them, and the vomer forms a 
large fusiform prominence on the upper surface of the base of the 
beak, in front of the blowers, between the narrowed part of the 
elongate, slender intermaxillaries, which are enlarged and thickened 
behind, forming the outer sides of the blowers. 
In this respect it agrees with the figure of the skull of Z. densi- 
rostris from the Indian Seas, given by M. Gervais (Zool. et Paléont. 
Frang. t. 40. f. 3-6) ; but the vomer is more prominent in the Cape 
species. The Cape species has the slender, elongated, tapering lower 
jaws, and a very much longer beak to the skull, like that of D. mi- 
cropterus of Havre (Gervais, /. c. t. 49. f. 1). 
7. The skull which, from the inspection of the drawing of Mr. 
Trimen, I was inclined to regard as a new species of Hyperoodon, 
forming a peculiar section of the genus, and which I had provisionally 
named Hyperoodon capensis (Proc. Zool. Soc. 1865, p. 359), proves 
on examination to be an entirely new form, which appears to be inter- 
mediate in structure and form between Hyperoodon and Catodon. 
It agrees with Catodon and Kogia in having a large concavity on the 
crown of the skull, to contain the spermaceti (or “ head-matter,”’ as 
it is called by the whalers), over the blowers, and with Hyperoodon 
in having an elongated beak, with thick prominent nasal bones over 
the blowers, and in having none or only two or four deciduous teeth 
in the front of the lower jaw. 
What I believed, in the small drawing made by Mr. Trimen, were 
the slightly developed lateral expansions of the maxillaries, which 
are characteristic of the genus Hyperoodon, prove on examination of 
the skull to have represented the much thickened intermaxillaries 
and the very large callous prominent vomer which is between them 
on the upper surface of the beak. The skull, as is generally the 
case in the Cetacea, is considerably distorted, the left side being 
much the smallest and least developed. 
The genus may be thus defined :— 
PrETRORHYNCHUS. 
The skull beaked ; the brain-case hemispherical, margined behind 
and on the sides by the prominent edges of the maxillz, occipital, 
