250 FAUNA ANTIQUA SIVALENSIS. 



and the average width of the whole series being to the length 

 as 2-13 to 1"76 inches. Their form is less prismatic; the 

 base of the shaft swelling out into a bulge or collar, from 

 which the inner surface slopes outward as it rises, so that 

 the coronal becomes somewhat contracted ; in the third molar 

 the width at the coronal is 1"93, at the bulge of the shaft 2'24. ■ 

 The ridges and hollows on the outer surface descend less upon 

 the shaft, and disapj)ear upon the bulge. There are no acces- 

 sory pillars on the furrow of junction at the inner side. The 

 crescentic jDlates of enamel have a character which distin- 

 guishes them from all known ruminants ; the inner crescent, 

 instead of sweeping in a nearly simple curve, runs zig-zag- 

 wise in large sinuous flexures, somewhat resembling the form 

 in Elasmotherium. 



The three double molars differ from each other only in their 

 relative states of wearing. The antepenultimate being most 

 worn, has the crescentic plates less curved, more approximate, 

 and less distinct ; the penultimate and last molars are less 

 worn, and have the markings more distinct. 



The three anterior or simple molars have the usual form 

 which holds in Ruminantia, a single semi-cylinder with but 

 one pair of crescents. The first one is much worn and 

 partly mutilated ; the second is more entire, having been 

 a shorter time in use, and finely exhibits the flexuous 

 curves in the sweep of the enamel of the inner crescent ; the 

 last one has the simple form of the permanent tooth which 

 replaces the last milk molar, it also shows the wavy form of 

 the enamel. 



Regarding the position of the teeth in the jaw, the last four 

 molars, viz. the three permanent and the last of replacement, 

 run in a straight line, and on the opposite sides are parallel 

 and equi-distant ; the two anterior ones are suddenly directed 

 inwards, so as to be a good deal approximated. If the two 

 first molars were not thus inflected, the opposite lines of teeth 

 would form exactly two sides of a square, the length of the 

 line of teeth and the intervals between the outer surfaces of 

 the four last molars being almost equal, viz. 9*8 and 9*9 

 inches respectively. 



The plane of detrition of the whole series of molars from 

 rear to front is not horizontal, but in a slight curve, and 

 directed upwards at a considerable angle with the base of the 

 skull, so that when the head is placed so as to rest upon the 

 occipital condyles and the last molars, a plane through these 

 points is cut by a chord along the curve of detrition of the 

 whole series of molars at an angle of about 45 degrees. This 

 is one of the marked characters about the head. 



