42 Description of the Sivatherium, [Jan. 



mence at the upper margin of the foi-amen magnum, and proceed upwards 

 and outwards. These alse are smooth, and are hollowed out downwards and 

 outwai - ds from near the condyles towards the mastoid region of the tem- 

 poral. Their inner or axine margins proceed in a ridge arising from the 

 border of the occipital foramen, diverging from each other nearly at right 

 angles, and enclose a large triangular fossa into which they descend 

 abruptly. This fossa is chiefly occupied by stone in the fossil, but it does 

 not appear shallow, and seems a modification of the same structure as in 

 the elephant. There is no appearance of an occipital crest or protube- 

 rance. The bone is mutilated at the sides towards the junction with the 

 temporals. Both here and at its upper fractured margin its structure is 

 seen to be formed of large cells with the diploe expanded into plates, and 

 the outer and inner laminae wide apart. This chai-acter is very marked 

 at its upper margin, where its cells appear to join on with those of the 

 frontal. The condyles are very large, and fortunately very perfect in the 

 fossil; the longest diameter of each is 4.4 inches, and the distance measured 

 across the foramen magnum, from their outer angles, is 7.4 inches : dimen- 

 sions exceeding those of the elephant. Their form is exactly as in the 

 Ruminantia, viz. their outer surface composed of two convexities meeting 

 at a rounded angle : one in the line of the long axis, stretching obliquely 

 backwards from the anterior border of the foramen magnum : on the other 

 forwards and upwards fi*om the posterior margin, their line of commissure 

 being in the direction of the transverse diameter of the foramen. The lat- 

 ter is also of large size, its antero-posterior diameter being 2.3 inches, and 

 the transverse diameter 2.6 inches. The large dimensions of the foramen 

 and condyles must entail a corresponding developement in the vertebra?, 

 and modify the form of the neck and anterior extremities. 



The sphenoidal bone, and all the parts along the base of the skull from 

 the occipital foramen to the palate, are either removed, or so concealed by 

 stone, as to give no characters for description. 



The part of the brow from which the nasal bones commence is not dis- 

 tinguishable. The suture connecting them with the frontal is completely 

 obliterated : and it is not seen whether they run up into a sinus in that 

 bone, or how they join on with it. Between the horns there is a rise in 

 the brow, which sinks again a little forward. A short way in advance of 

 a line connecting the anterior angles of the orbits, there is another rise in 

 the brow. From this point, which may be considered their base, the nasal 

 bones commence ascending from the plane of the brow, at a considerable 

 angle. They are broad and well arched at their base, and proceed for- 

 ward with a convex outline, getting rapidly narrower, to terminate in a 

 point curved downwards, which overhangs the external nostrils. For a 

 considerable part of their length they are joined to the maxillaries : 

 but forwards from the point where they commence narrowing, their lower 

 edge is free and separated from the maxillaries by a wide sinus : so that 

 viewed in lateral profile their form very much resembles the upper 

 mandible of a hawk, detached from the lower. Unluckily in the fossil, 

 the anterior margins of the maxillaries are mutilated, so that the exact 

 length of the nasal bone that was free from connection with them cannot 

 be determined. As the fossil stands, about four inches of the lower edge 

 of the nasals, measured along the curve, are free. The same mutilation 

 prevents its being seen how near the incisives approached the nasals, 

 with which they do not appear to have been joined. This point is one of 

 great importance, from the structure it implies in the soft parts about the 

 nose. The height and form of the nasal bones, are the most remarkable 

 feature in the head : viewed from above they are seen to taper rapidly 

 from a broad base to a sharp point ; and the vertical height of their most 

 convex part above the brow at their base, is 3^ inches. 



