334 MR. W. H. FLOWER ON THE OSTEOLOGY OF THE SPERM-WHALE. 
part of the side of the posterior end of the conjoined bodies, or that part which appears 
to be connected with the seventh neural arch, and may therefore be regarded as re- 
presenting the centrum of the seventh vertebra, occupies a space as large as the three 
antecedent vertebre together (deciphered by the same test), and is raised into two 
rugged ridges with a groove between, of which ridges the anterior is rather the more 
prominent. Besides these, there is no indication either of process or of articular facet 
for the first rib. As the more posterior of these ridges is situated quite at the edge of 
the vertebral body, and rather higher up than the other, it may be regarded as the 
representative of this facet; and the rib may have had a ligamentous connexion with it, 
for the form of its head would not allow it to come in contact with the bone itself. 
The other is probably a rudiment of an inferior transverse process. 
A distinct upper transverse process (diapophysis, Owen) is present only on the 
seventh vertebra. It springs from the middle of the side of the neural arch by a base 
of about 2” in breadth, and is of the same length, irregularly triangular, and very 
much compressed. Certain small irregular projections from the edges of the deli- 
cate lamelle of bone which constitute the lateral parts of the neural arches of the 
third, fourth, fifth, and sixth vertebre are the only representatives of their transverse 
processes, 
The neural arches of these vertebree may be considered in the two portions into which 
they naturally resolve themselves. 1. The lateral portions, springing up from the con- 
joined bodies. 2. The united mass forming the roof of the neural canal, composed of 
the conjoined spines. ‘The lateral parts of the arches are, as before said, all distinct. 
The first (that of the axis) far surpasses the others in breadth and in stoutness. Next 
to it the last or seventh is the best developed. Between these two are placed four 
delicate brittle lamelle, scarcely thicker than cardboard, the third and sixth being 
rather stouter than the two middle ones. So brittle are these plates, that in neither of 
the three sets of cervical vertebrae examined haye the whole of them escaped destruc- 
tion in the cleaning-process; sufficient remains, however, in every case to show that 
their general arrangement is the same. ‘The intervals between them are of nearly equal 
width (}”), but diminish in height from before backwards, the first being 23”, and the 
last scarcely more than 1” high. ‘The upper part of the arch is formed of a transversely 
elongated rugged mass of bone, flattened from before backwards, with two prominent 
square shoulder-like lateral projections rising from the anterior surface, and with a 
small pointed spine in the middle line surmounting the posterior edge. Between this 
spine and the two shoulders rising on each side and in front of it is a distinct groove. 
‘These lateral expansions, which appear to belong chiefly to the axis, are, among Toothed 
Whales at least, quite peculiar to Physeter. Even Hyperoodon shows no trace of them, 
as the conjomed neural arches of the first six cervical vertebra rise smoothly and 
gradually into a greatly elevated spinous process. The axis of the Balwnoptere presents 
rugged lateral processes somewhat similar to those of the Sperm-Whale. 
