PROF, W. H. FLOWER ON THE GENUS MESOPLODON. 429 
bury Museum, New Zealand, which has C. 7, D. 10, L. 10,C. 19 = 46 (Haast, P. Z. S. 
1876, p. 481). 
The cervical vertebre of the two skeletons are very much alike; indeed, considering 
the difference of age and the great tendency to individual variation, it may be doubted 
whether any differences that may justly be called specific can be detected between 
them. In both the atlas and axis are completely united by the whole of the body and 
arch, except for the spaces in the latter which constitute the foramina for the exit of 
the second cervical nerves ; in both all the other vertebra are perfectly free’. This is 
the minimum of vertebral union known in any Ziphioid, and is the same which occurs 
in the specimens of J. bidens at Brussels and at Gothenburg. In MM. layardi the 
atlas and the second and third cervical vertebre are united into one large triangular 
bone, the rest are all free*. In the skeleton of Berardius arnouai, in the Museum of 
the College of Surgeons, the third is united by its body to the completely conjoined 
first and second. In the fine skeleton of Zphius cavirostris from Villa Franca, in the 
Museum at Jena, the first, second, and third vertebre are completely united by their 
bodies, and the fourth is joined to them by the spine. In another specimen from 
Corsica, described by Fischer, the six anterior vertebre are united. In the Gothenburg 
Ziphius the first four are joined. In Hyperoodon the bodies of all seven are firmly 
united together, and the spines of all except the seventh join to form a single elevated 
conical mass. ; 
The arch of the atlas bears in both specimens a complete foramen for the passage 
of the cervical or suboccipital nerve, not a groove only, as in Berardius. In other 
respects these bones bear a great resemblance to those of that genus, more than they 
do to Ziphius and, & fortiori, to Hyperoodon. 
In I. grayi the upper and lower transverse processes of the axis are united on the 
left side, leaving only a small circular foramen between them at the base; but on the 
right side in this specimen, and on both in J/. australis, the processes are quite distinct. 
and separated by a wide notch. In all the other vertebra, as far as the sixth, the 
upper and lower processes are present and not united. They are developed in a nearly 
corresponding’ degree in the two specimens, except that in the sixth vertebra the upper 
process is very rudimentary in W/. australis, and the left lower process is developed to 
nearly double the length of the right. ‘This is evidently an individual peculiarity. 
These processes differ very considerably from the corresponding parts of Berardius, 
as they are directed downwards, outwards, and in the main backwards, instead of for- 
wards as in Berardius, in which it is the anterior portion of the process, and not the 
principal or posterior part, which is chiefly developed *. 
The arches and spines of the cervical vertebre are better developed generally than in 
1 Dr. Haast tells me in a letter (Dec. 12,1876) that in the skeleton of an adult female of IZ. grayi the third 
cervical vertebra is united to those before it. 
2 Haast, P. Z. 8. 1876, p. 482. * See Trans. Zool. Soc. vol. viii. p. 225, 
