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joint, which differs from the usual formation of this joint in other mammals. 

 The posterior aspect of the neural aperture shows a noticeable expansion. 



The second vertebra, epistropheus or axis (fig. 13 and 14) fits so closely 

 against the posterior surface of the atlas as to render movement between these 

 t^vo vertebrae hardly possible. An odontoid pivot of the epistropheus on which 

 the revolving of the atlas in most mammals takes place is not present either, 

 unless a granular emergence at the centre of the anterior cup of the epistro- 

 pheus may be looked upon as a rudiment of this organ (fig. 13). 



In comparison with Balaenoptera schlegelii Flower there are left for me 

 to point out the following differences: 



The articular surface towards the atlas does not consist of two parts 

 but of one continuous surface. The spinous process is larger and, especially 

 when compared with those of the other cervical vertebrae, it forms a strikingly 

 ponderous mass. The lateral processes are more rectangular, and are directed 

 backward but not downward at all, the apertures occurring in these are 

 proportionally smaller. 



If we except the first two vertebrae, we find that the general type of 

 the cervical vertebrae is best represented by the middle one of those remaining, 

 i.e. the 5th vertebra (fig. 17). 



As typical characters we find: the centrum is flat and rectangular, more 

 or less rounded at the corners; the vertebral foramen large and triangular. 

 The spinous process, formed by two bone-plates meeting roofwise, is low 

 and little developed, the articular prominences are small, but the articular 

 facets of these processus articulares of the successive vertebrae still meet, 

 and lateral processes form great plane arches. 



In the 5th vertebra the plane of these lateral processes is perpendicular 

 to the axis of the body, whereas the three previous and the two succeeding 

 cervical vertebrae suggest that they are compressed towards the centre of 

 the group of vertebrae colli (the 5th). In the third and fourth vertebrae (fig. 

 15 and 16) the spinous process is not closed at the top, but consists of two 

 very thin lamina of bone, whilst not much more remains of the articular 

 processes than the articular facets. In the 5th vertebra (fig. 17) these latter 

 processes are of a more pronounced character. 



In the 6th vertebra (fig. 18) the transverse process does not form a 

 closed arch, the latter being interrupted just below the middle, so that the 

 two parts genetically produced by two distinct ossifications, are seperately 



