138 



575. Three large and some smaller fragments of a large molar of the Mam- 



moth ; showing in many parts the direction of the tubular fibres of the 

 dentine. 



Locality unrecorded. Hunterian. 



576. The lower molar of the Mammoth, wanting some of the anterior plates. 



The main part of the crown, which is six inches and a half in length, 

 exhibits the summits of twelve plates ; the primitive form of these 

 plates is well shown in the posterior part of the tooth. Their summits are 

 each divided into three mammillary processes, the marginal ones bending 

 obliquely inwards and forwards towards the middle one, which is itself 

 subdivided into two or three smaller protuberances. The successive abra- 

 sion of the summits of these primary and secondary divisions of the plates 

 gives rise to the variety of form in the exposed summits of the plates of 

 the posterior half of the grinding surface of the tooth. The external 

 cement has been decomposed and lost. The lower surface of the tooth 

 is excavated by a broad pulp-channel, not yet inclosed by the formation 

 of fangs. 



Locality unrecorded. Hunterian. 



577. The posterior portion of an upper molar of the Mammoth, in which the 



three constituents of the tooth are well displayed by their difference of 

 colour : the dentine being of a dark brown, the enamel bluish black, 

 and the cement of almost its natural yellowish white colour. 

 From the pleistocene beds or till at Walton, in Essex. 



Presented by Sir IVilliam B lizard, F.R.S. 



578. A considerable portion of the incompletely formed crown of a molar of a 



large Mammoth, partly resolved by decomposition of the cement, or 

 third substance, into its constituent plates. 



Locality unrecorded. Hunterian. 



579. A portion of a molar of a Mammoth similarly decomposed, but with a 



greater degree of carbonization of the animal matter of the tooth. The 

 disposition of the calcigerous tubes of the dentine is beautifully shown 

 in some parts of this specimen. 



Locality unrecorded. Hunterian. 



