206 PROFESSOR FLOWER ON THE RECENT ZIPHIOID WHALES, 
It must be premised that as far as is at present known, putting aside the peculiar 
rounded form of the head in Hyperoodon, the external characters of the various known 
Ziphiine afford no grounds for generic subdivision. It is to the skeleton and the teeth 
that we must look in examining whether the group is truly homogeneous or not; and it 
is only very recently that complete skeletons of a sufficient number of individuals have 
been known, to attempt a comparison between them. ‘The teeth have been relied upon 
almost entirely; and I agree with Professor Owen that the trifling differences in the 
situation of the developed teeth are not such as, unless accompanied by other more 
important and constant characters, are sufficient for generic distinction; but, at the 
same time, if such differences are constantly associated with others, they may be useful 
guides to classification. 
Hyprroopon (Lacépéde) appears to differ from all the other Ziphiine in the cha- 
racters of the cervical vertebree, especially in their great antero-posterior compression, 
the constant ankylosis of all seven, and the absence of inferior transverse processes 
in the third, fourth, fifth, and sixth’; it has also only nine pairs of ribs, and but forty- 
five vertebre in all’, In the more essential characters of the cranium it resembles one 
of the other sections to be spoken of presently (J/esop/odon), with the superaddition of 
the great maxillary crests; and in the dentition it resembles more nearly another 
section (Ziphius). 
Having separated Hyperoodon, the remaining known members of the subfamily agree 
in having a comparatively well-developed cervical region, with certain of the posterior 
vertebree (one, or usually more) permanently detached, and with distinct inferior 
transverse processes as far as the sixth, in having almost always ten pairs of ribs* 
and at least forty-six vertebree, usually forty-eight or forty-nine. There are, however, 
in the conformation of the skull and the form and situation of the teeth considerable 
differences, by which they may be divided into three distinct sections, which appear to 
me to be natural, and which are not, as far as is yet known, united by intermediate 
forms; so I think that they may well be considered generic, though of course this is 
a subject upon which the judgment of zoologist§ may differ. I can see no grounds 
at present for any further subdivision. 
These sections may be characterized as follows—though the distinctive peculiarities 
are more readily appreciated by an inspection of a specimen than they can be expressed 
in words. 
1 The great differences between the cervical yertebre of Hyperoodon and Ziphius cavirostris (erroneously 
called Hyperoodon gervaisii) were pointed out by Duvernoy (Annales des Sciences Naturelles, 1851, p, 24). 
? The animal described by Cope, apparently without personal examination, as Hyperoodon semijunctus (Proc, 
Acad. Nat. Se. Philadelphia, 1865, p. 280), and stated to be in the Charleston Museum, is evidently not a 
Hyperoodon, but most probably a true Ziphius. It was but between twelve and thirteen feet long, has the 
four posterior cervical yertebrie free, has ten pairs of ribs, and two more vertebrae than Hyperoodon. 
3 The skeleton of Ziphius cavirostris at Jena has but nine pairs of ribs, 
