638 UNGULATES. 



transverse plates were thinner and more numerous ; they are also 

 deeper, and more subdivided into digitated summits : and we may- 

 infer from the resulting increase of the dense enamel which enters 

 into the formation of the broad grinding surface, that the extinct 

 species had to subsist on a coarser and more ligneous vegetable 

 diet, in conformity with the colder regions of the ancient world 

 in which its peculiar warm clothing of wool and hair adapted it 

 to exist. 



The phenomena of the course and changes of the dentition 

 of the Elephas Africanus have a close analogy with those of the 

 preceding species with more complex teeth. The first molar has 

 a four-ridged crown, with two long diverging fangs ; the specific 

 characters are least manifested in this early-developed tooth : they 

 become more marked in the subsequent molars. The second has 

 seven plates, five of normal size and already manifesting the cha- 

 racteristic median expansion ; the first and last plates are much 

 smaller : the length of this tooth is two inches and a quarter. 

 The third molar manifests an increase in the size and thick- 

 ness of the coronal plates, and of the width of their cement-filled 

 interspaces, but not any in the number of the divisions; the first, 

 however, presents more of the normal proportions. The fourth molar 

 manifests a marked increase of size and especially of breadth, but its 

 crown is not divided into more than seven plates. The fifth molar, 

 (PI. 148, fig. 4) which is about seven inches in length, has eight 

 or nine coronal plates. The sixth molar, eight or nine inches in 

 length has from ten to twelve plates in the lower jaw. 



The molar teeth in all the species of Elephant succeed each 

 other from behind forwards, moving, not in a right line, but in the arc 

 of a circle (PI. 146, fig. 1) : the position of the growing tooth in the 

 closed alveolus (m 5) is almost at right angles with that of the molar in 

 use, the grinding surface being at first directed backwards in the upper 

 jaw, and forwards in the lower jaw, and brought by the revolving 

 course into a horizontal line in both jaws, so that they oppose each 

 other, when developed for use. The imaginary pivot on which 

 the grinders turn is next their root in the upper jaw, and is 

 next the grinding surface in the lower jaw ; in both towards the 



