ELEPHANT. 631 



fig. 4), on the other hand, the lamellar divisions of the crown 

 are fewer and thicker, and they expand more uniformly from 

 the margins to the centre, yielding a lozenge-form when cut or worn 

 transversely. 



The horizontal as well as vertical course of development of the 

 Elephant's grinder is well illustrated by the Mammoth's molar, 

 the last of the lower jaw, in PI. 148, fig. 5. The separate digital 

 processes (//) of the posterior plates are still distinct, and adhere 

 only by the remaining cement; a little in advance we see them 

 united to form the transverse plate ; and, at the opposite extremity 

 of the tooth, the common base of dentine (d^) is exposed by which 

 the plates are finally blended into one individual complex grinder(l) : 

 this never takes place simultaneously along the whole course of the 

 tooth in the larger molars of the existing Indian Elephant, or its 

 extinct congener, the Mammoth. The African Elephant, and some 

 of the extinct Indian species, as the El. planifrons, (PL 147, fig. 1), 

 manifest their affinity to the Mastodon by the basal confluence 

 of the hindmost plates before the foremost ones are worn out. The 

 grinders of the El. planifrons are also distinguished from the existing 

 species by the number of roots (ib. d d), and the extent of the 

 base {a a) from which they are simultaneously developed. 



The formation of each grinder begins with the summits of the 

 anterior plate, and the rest are completed in succession ; the tooth is 

 gradually advanced in position as its growth proceeds, and, in the 

 existing Indian Elephant, the anterior plates are brought into use 

 before the posterior ones are formed. When the complex molar cuth 

 the gum the cement is first rubbed oflf the digital summits : then 

 their enamel cap is worn away, and the central dentine comes into 

 play with a prominent enamel ring : the digital processes are next 

 ground down to their common uniting base, and a transverse tract 



(1) Some anatomists describe the divisions of the crown of the Elephant's grinder as 

 entire teeth; and Mr. Corse, (loc. cit. p. 213) who first propounded this view, calls 

 each complex grinder ' a case of teeth,' and states " that these teeth are merely joined to each 

 other by an intermediate softer substance, acting like a cement." But this description applies 

 only to the incompletely formed tooth ; and the detached eminences of the crown of any complex 

 tooth, at that stage of growth when they are held together only by the still uncalcified support- 

 ing matrix, might with equal justice be regarded as so many distinct teeth. 



