334 MR. W. H. PLOWEE OX THE OSTEOLOGY OP THE SPEEM-WHALB. 



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 vertebrae 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 {dicqwphysis, 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 tlie same length, irregularly triangular, and very 

 much compressed. Certain small irregular projections from the edges of the deli- 

 cate lamellae of bone which constitute the lateral parts of the neural arches of the 

 third, fourth, fifth, and sixth vertebrae are the only representatives of their transverse 

 processes. 



The neural arches of these vertebrae 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 arc, 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 lamellae, 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 exammed have 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 2^", 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 sui-mounting the posterior edge. Between this 

 spme 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 Fhyseter. Even Hijperoodon shows no trace of them, 

 as the conjoined neural arches of the first six cervical vertebrae rise smoothly and 

 gradually into a greatly elevated spinous process. The axis of the Bahenopterw presents 

 ragged lateral processes somewhat similar to those of the Sperm- Whale. 



