134 



of distinct slender cylindrical columns, and might be regarded as an 

 aggregate of separate cylindrical denticules with the same reason as the 

 entire molar tooth has been described to consist of an aggregate of 

 lamelliform denticules. The cylindrical denticules are, however, ulti- 

 mately blended together by a common dentinal base, constituting the 

 lamelliform denticle : and these denticles in like manner next coalesce 

 to 'form the common dentinal base of the molar tooth, from which the 

 true roots of the tooth are developed. Thus the apparent independency 

 of the cylindrical and lauielliform denticles depends upon an incomplete 

 state of the development of a complex but essentially single and indi- 

 vidual tooth. 



The development of this complex tooth has proceeded in the extinct, 

 as it does in the existing Elephant, not only from the summit to the 

 base, but from the fore to the back part : in the present example, the 

 anterior part of the tooth shows the lamelliform divisions of the crown 

 worn down to the common base, which is supported by well-developed 

 fangs ; at the back part of the tooth the columnar or cylindrical portions 

 of the constituent plates are not yet united by the calcification of the 

 continuous lamelliform base, and the plates so formed may be observed 

 in every successive stage of growth as they advance towards the part 

 where their own uniting base and the fangs begin to be formed. 



The present fossil grinder is fourteen inches in length, the anteropos- 

 terior extent of the grinding surface is seven inches, the transverse dia- 

 meter three inches and a half. The crown is divided into twenty-two 

 lamellae, ten of which have come into use ; the middle mammillary process 

 of the posterior and least abraded lamellae is twice the breadth of the 

 marginal processes ; but, as the lamella? advance in position, the marginal 

 mammillae acquire the breadth of the median one, and the whole become 

 blended together in the more abraded plates. 



The enamel boundary of the transverse plates is plicated like a frill in 

 this tooth. 



From British drift or pleistocene beds. Hunterian. 



d(57- The lower molar tooth of the right side of the same Mammoth, 



