on the Sivatherium giganteum. 197 



bone the skull is fractured, and the structure of the bone is exposed. The 

 internal and outer plates are seen to be widely separated, and the interval 

 to be occupied by large shells, formed by an expansion of the diploe into 

 plates, as in the elephant. The interval exceeds 2i inches in the occipital. 

 On the left side of the frontal, the swelling at the vertex has its upper 

 lamina of bone removed, and the cast of the cells exhibits a surface of 

 almond-shaped or oblong eminences, with smooth hollows between. 



The temporal is greatly concealed by a quantity of the stony matrix, 

 which has not been removed from the temporal fossa. No trace of the 

 squamous suture remains to mark its limits and connexion with the frontal. 

 The inferior processes of the bone about the auditory foramen have been 

 destroyed, or are concealed by stone. The zygomatic process is long, and 

 runs forward to join the corresponding apophysis of the jugal bone, with 

 little prominence or convexity. A line produced along it would pass in front, 

 through the tuberosities of the maxillaries, and to the rear along the upper 

 margin of the occipital condyles. The process is stout and thick. The tem- 

 poral fossa is very long, and rather shallow. It does not rise up high on the 

 side of the cranium : it is overarched by the cylinder-like sides of the frontal 

 bone. The position and form of the articulating surface with the lower jaw 

 are concealed by stone which has not been removed. 



There is nothing in the fossil to enable us to determine the form and 

 limits of the parietal bones ; the cranium being chiefly mutilated in the 

 region which they occupy. But they appear to have had the same form 

 and character as in the ox ; to have been intimately united with the occi- 

 pitals, and to have joined with the frontal at the upper angle of the skull. 



The form and characters of the occipital are very marked. It occupies 

 a large space, having width proportioned to that of the frontal, and consi- 

 derable height. It is expanded laterally into two alse, which commence at 

 the upper margin of the foramen magnum, and proceed upwards and out- 

 wards. These alae are smooth, and are hollowed out downwards and out- 

 wards from near the condyles towards the mastoid region of the temporal. 

 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 inclose 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 protuberance. 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 character 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 fortiaiately very perfect in the fossil ; the longest dia- 

 meter of each is 44 inches, and the distance measured across the foramen 

 magnum, from their outer angles, is 7'4 inches : dimensions exceeding 

 those of the elephant. Their form is exactly as in the liuniinantia, 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 from the posterior margin, their line of commissure being in 

 the direction of the transverse diameter of the foramen. The latter is also 

 of large size, its aritero-posterior diameter being 23 inches, and the trans- 

 verse diameter 26 inches. The large dimensions of the foramen and con- 

 dyles must entail a corresponding development in the vertebrae, 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. 



