SIVATHEKIUM GIGANTEUM. 269 



II. — MS. Notes on Bones op Sivatherium not described 



IN Memoir. 



Atlas. — The form of the atlas, from two fragments which 

 exist of it, appears to have been very different from that of aU 

 living ruminants. The body of the vertebra and the arc 

 surrounding the medullary canal are not peculiar. The an- 

 terior articulating surface resembles that of the eland ; the 

 two cavities are continued to the median line, without any 

 mesial ridge as in the eland. The posterior articulating sur- 

 face resembles in every respect that of the buffalo. Below, 

 the body of the vertebra is not distinct, as in the buffalo and 

 eland, where on each side it forms a right angle, but the body 

 passes into the transverse apophysis by a slightly inclined 

 plane, as in the giraffe. As a result of this, the foramen in 

 the transverse process is not concealed by the body of the 

 vertebra. But the remarkable feature of the atlas consists 

 in the form of the transverse process. In the rviminants 

 this process is depressed ; it is very large posteriorly, and 

 diminishes gradually in front, where it presents a straight 

 edge. In the Sivatherium the transverse process is much 

 less developed. At its middle it is very narrow, but it ex- 

 pands a little at the two extremities of the bone, in such a 

 way that the outer part of the process is concave towards the 

 body. The four angles of the bone form almost a square, 

 perhaps slightly wider in front than behind, but the extremi- 

 ties of the transverse processes are too worn to determine this 

 point with certainty. Length of body, 3-3 inches; minimum 

 breadth a little behind the middle of the body, 7-8 ; extreme 

 breadth of articulatiiag surface with axis, 6-7. The corres- 

 ponding measurements in buffalo are 2*1 ; 10-4; and 5. 



[The specimens of the atlas referred to are in the British 

 Museum. Cat. ISTos. 39,526 and 39,-527. They are both 

 figured in an unpublished plate of F.A.S. (B. 1 and 2). — Ed.] 



Axis. — In form the axis is that of a ruminant. It resembles 

 that of the eland and of the ox in the situation of the foramen, 

 by which the vertebral artery enters the spinal canal anteriorly, 

 and also in the form of the odontoid process and of the arti- 

 culating surface of the atlas ; below, at the middle of this 

 surface, there is not the cleft seen in the eland, nor the echan- 

 crure observed in the buffalo. The spinous jjrocess projects a 

 little more backwards. The posterior articulating surfaces 

 project less backwards and are more distant from one another 

 than in the eland. In this respect they resemble those of 

 buffalo. Length of body with odontoid process, 7*6 inches ; 

 width of articulating surface with atlas, 5-7. 



