SIVATHERIUM GIGANTEUM. 249 



the rise and sweep in the bones of the nose give a character 

 to the head widely differing from that of any other animal. 

 The nose looks something like that of the rhinoceros, hut 

 the resemblance is deceptive, and only owing to the mnzzle 

 beinsf truncated. Seen from the front, the head is somewhat 

 wedge-shaped, the greatest width being at the vertex, and 

 thence gradually compressed towards the muzzle, with con- 

 traction oiily at two points behind the orbits and under the 

 malars. The zygomatic arches are almost concealed and 

 nowise prominent ; the brow is broad and flat, and swelling 

 latterly into two convexities ; the orbits are wide apart, and 

 have the appearance of being thrown far forward, from the 

 great production of the frontal upwards. There are no crests 

 or ridges ; the surface of the cranium is smooth, the lines are 

 in curves, with no angularity. From the vertex to the root 

 of the nose the j)laue of the brow is in a straight line with 

 a slight rise between the horns. The accompanying draw- 

 ings will at once give a better idea of the form than any 

 description. (Plates XIX. and XX.) 



Now, in detail of individual parts, and to commence with 

 the most important and characteristic, the teeth : — 



There are six molars on either side of the upper jaw. The 

 third of the series, or last milk molar, has given place to the 

 corresj)onding permanent tooth, the detrition of which and of 

 the last molar is well advanced, and indicates the animal to 

 have been more than adult. 



The teeth are in every respect those of a ruminant, with 

 some slight individual peculiarities (See Plate XX. fig. 1). 



The three posterior or double molars are composed of two 

 portions or semi-cylinders, each of which encloses, when par- 

 tially worn down, a double crescent of enamel, the convexity 

 of which is turned inwards. The last molar, as is normal in 

 ruminants, has no additional complication, like that in the 

 corresponding tooth of the lower jaw. The plane of grinding 

 slopes from the outer margin inwards. The general form is ex- 

 actly that of an ox or camel, on a large scale. The ridges of 

 enamel are unequally in relief, and the hollows between them 

 unequally scooped. Each semi-cylinder has its outer surface 

 in horizontal section, formed of three salient knuckles, with 

 two intermediate sinuses ; and its inner surface, of a simple 

 arch or curve. But there are certain peculiarities by which 

 the teeth differ from those of other ruminants. 



In correspondence with the shortness of jaw, the width of the 

 teeth is much greater in proportion to the length than is nsual 

 in the family : the width of the third and fourth molars being to 

 the length as 2-24 and 2*2 to 1-55 and 1-68 inches, respectively; 



