1836.] Fossil Remains of the Dddupitr Collection. 665 



and more tapering than the one in fig. 6. Between this the initial 

 step in the dentition, and that in which the 6th molar is making its 

 appearance, we have none of the intervening stages. A cranium 

 which has not heen drawn in consequence of the mutilation of all the 

 molars except the 5th, shows the 6th tooth in the act of cutting the 

 jaw : the anterior extremity of the intermaxillary being broken off, 

 the incisor teeth are not perfect, but by the fracture the permanent 

 incisors are in part laid open, so that the milk ones must either have 

 already fallen or have been on the point of so doing : the latter is 

 the most probable, as the lower jaw of this cranium, of which fig. 2, 

 Plate C, is a representation, has the first set of incisors still in the 

 jaw, though much worn ; of course the state of detrition of the molars 

 of the upper corresponds with that of the teeth of the lower jaw ; the 

 4th molars are very much worn, the 5th has commenced to be in use, 

 and the 6th is showing the summits of its collines ; it appears to be 

 during the progressive wear of the 5th and the descent of the 6th 

 molar that the milk teeth are shed and replaced by the permanent 

 ones ; for fig. 1 , Plate B, which represents the right half of a speci- 

 men, has no vestige of the milk teeth, but shows the permanent mo- 

 lars Nos. 1, 2, 3, 4, and 6 unworn. 



As the animal increased in age and the 7th molar gradually de- 

 scended, the teeth already in use assumed the appearance exhibited 

 by fig. 2, Plate B, which represents the left half of a fossil upper 

 jaw : this and the foregoing specimen, fig. 1, show that the 1st, 2nd, 

 3rd, 4th, 5th, 6th molars, excepting in size, correspond with those 

 of the existing species, each tooth being compounded of the same parts, 

 even to the small external interstitial pillars of the 5th and 6th. The 

 7th is in fig. 2 quite untouched, only the anterior portion of the 

 tooth having, in fact, been exposed ; although in consequence of the 

 breaking away of the posterior part of the specimen the whole of the 

 molar is now exposed. Compared with a germ of the existing species, 

 it is found to be composed of analogous parts, the general shape of 

 the fossil tooth being at the same time modified in consequence of 

 the greater size to which the posterior collines or mamillse attain : 

 hence the tooth is comparatively longer and less tapering. 



Fig. 5, which represents the left half of a fossil cranium, shows the 

 7th molar in great part brought into use, and the corresponding pro- 

 gress in the detrition of the other teeth. In fig. 3, Plate B, which 

 is a view of th3 left half of the palate of the cranium fig. I , Plate 

 XXXIV., the whole of the last molar has been brought into use. The 

 1st molars are in this specimen mutilated, the others evince the wear 

 4 R 



