296 



cavity; four articular, the posterior of which are short, and are directed 

 outwards ; and two transverse, which are thick and short. Their bodies 

 are longer than wide, and wider than high ; their faces are transversely 

 oval. Those of the middle of the back have not the inferior apophysis, 

 but resemble the preceding in every thing else. The last of the back, 

 those of the loins, and of the beginning of the tail, have no articular 

 apophyses, and their places may be known by their transverse apophyses, 

 which become elongated and flattened. The articular surfaces of the 

 posterior of these vertebrae are nearly triangular. The next of the tail, be- 

 sides their superior spinous apophysis, and the two transverse, have at 

 their inferior side two small surfaces to receive the angular bone *, (los 

 en chevron). The articular surfaces of these vertebra? are pentagonal. 

 The next set, Plate XVIII. Fig. 8, differ from the preceding in not 

 having any transverse apophyses. These form a large part of the tail. 

 The angular bone a is not here articulated, but united into one body 

 with the vertebra. The succeeding vertebrae become more and more 

 -compressed at the sides; nd, as they approach the end of the tail, cease 

 to have any apophyses at all. 



This series of vertebrae gives opportunity to M. Cuvier to offer some 

 important observations. The angular bone first claims his attention. Its 

 great length, with that of the spinous apophysis, which is opposite to it, 

 sufficiently prove that the tail of this animal was considerably extended 

 vertically. The absence of the transverse apophyses from a consider- 

 able part of the length of the tail, prove, at the same time, that it was 

 much flattened at the sides. Hence he concludes, that this animal was 

 aquatic, and swam in the manner of the crocodile, working its vast tail, 

 as an oar, from side to side, and not upwards and downwards, as in the 

 cetacea. 



* That which I have termed angular bone, and which is by the -French designated by the 

 term Vos en chevron, is a bone, of which several are sometimes placed at the juncture of the 

 yertebrae of the tail, on their lower part, where they are disposed so as to form an angle, as 

 in the letter V. 



