164 



the exception of the last, the mammillary summits have been abraded. 

 Of the succeeding molar five of the ridges of the crown have emerged 

 from their socket. 



From the tertiary formations of the Sub-Himalayan district, India. 



Presented by Thomas Bacon, Esq. 



6"0. A part of the left ramus of the same jaw, with the corresponding teeth ; 

 a part is broken off from the posterior tooth, showing the depth of the 

 transverse fissures of the grinding surface. 

 From the same formation and locality. 



Presented by Thomas Bacon, Esq. 



671. A portion of the left ramus of the lower jaw of the Mastodon elephan- 



toides, with a molar tooth in situ. It is sawn through vertically in the 

 axis of the jaw, and shows the depth and thickness of the folds of enamel 

 that line the interspaces of the ridges at the posterior part of the tooth ; 

 these have been obliterated by attrition at the anterior part of the tooth, 

 where the common base of dentine is exposed. A long and thick fang 

 is developed from the posterior part of the tooth. 



From the tertiary formations of the Sub-Himalayan district, India. 



Presented by the Rev. E. Everest, F. G.S. 



672. A portion of the crown of a molar tooth of the Mastodon elephantoides, 



on one of the fractured surfaces of which the course of the dentinal 

 tubes is indicated. 



From the tertiary formations of the Sub-Himalayan district, India. 



Presented by the Rev. E. Everest, F.G.S. 



673. One of the transverse ridges of a large upper molar of the Mastodon ele- 

 phantoides, broken across vertically, and beautifully displaying the course 

 of the enamel-fibres on the fractured surfaces. 



From the tertiary formations of the Sub-Himalavan district, at Nahn. 

 Presented by H. Clark, Esq, Swgeon H.E.I.C. 



674. A portion of the lower jaw with the corresponding part of a molar tooth 



