630 UNGULATES. 



and like so many separate teeth or denticles, until their base is 

 completed, when it becomes blended with the bases of contiguous 

 plates to form the common body of the crown of the complex 

 tooth, from which the roots (ib. r r) are next developed. 



But the growth of each constituent plate is analogous to, and 

 almost as complex as that of the entire tooth ; for each plate consists 

 at the beginning of a series of separate slender conical columns 

 or digital processes (PL 146, fig. 4), arranged transversely across 

 the tooth. The formation of these columns likewise begins at their 

 summit, and descends, their bases gradually expanding until they 

 are blended together to form a continuous transverse plate (ib. 

 fig. 5.)(1); just as the plates are subsequently blended together to 

 form a continuous longitudinal crown of the grinder. After the 

 digital processes have coalesced to form the transverse plate, the 

 sides of this plate, which in the Asiatic Elephant are parallel, become 

 wrinkled or undulated : giving a similar character to the Hne of 

 enamel, when the surface of the tooth has been worn down to this 

 point. The lateral margins of the plates are rounded and, though 

 covered by a thick cement, still project so as to give a vertically 

 ribbed surface to the sides of the complex molar (PI. 148, fig. 5) ; 

 when the cement is detached the margin of the plate is seen to 

 be undulated by a number of small transverse risings : this structure 

 is beautifully shown in some of the molars of the Mammoth, a 

 portion of one of these is figured in PI. 148, fig. 7.(2) 



The plates of the molar of the Elephas primigenius are thinner 

 in proportion to their breadth, and are generally a little expanded 

 at the middle : the enamelled border is often undulated, as in 

 the Elephas asiaticus, and sometimes with a greater degree of 

 regularity. The coronal plates are in general more numerous in 

 proportion to the size of the crown in the Mammoth, than in the 

 El. asiaticus. (Compare fig. 6, molar of Mammoth, with fig. 3, 

 molar of Indian Elephant in Plate 148). In the El. africanus 



(1) Such detached plates of the large molars of the Mammoth offer a rude resemblance to 

 a hand, and may be found figured in the works of the older collectors of petrifactions, under 

 the name of ' Cheirolites,' as the fossilized hand of a monkey or a child. 



(2) See ' History of British Fossil Mammalia,' 8vo. p. 337, fig. 91. 



