183 



similarly abraded from the opposite side ; all the edges have been 

 rounded off. 



From the tertiary formations of Ohio. Pttrchased. 



74S. A fragment of the tusk of a proboscidian Pachyderm, probably the Mas- 

 todoTi giganteus, one side of which has been similarly abraded and 

 polished. 



From the tertiary formations of Ohio. Purchased. 



749. A portion of the base of the tusk of a proboscidian Pachyderm, pro- 

 bably the Mastodon giganteus, one-half of which has been worn away 

 lengthwise, and the pulp-cavity laid open ; the successive conical layers 

 into which the ivory is resolved by decomposition are well shown in this 

 fragment. 



The marks of abrasion in this and the two preceding specimens are 

 most probably due to inorganic forces operating after death. 



From the tertiary formations of Ohio. Purchased. 



Bones of the Trunk and Extremities. 



750. The atlas of a Mastodon gigajiteus ; it differs from that of the Elephant 



and Mammoth principally by the obtuse conical production of the 

 under part of the body of the vertebra. 



From the tertiary formations of Ohio. Purchased. 



751. The atlas of the Mastodon giganteus: both transverse processes are 



broken off: the inferior protuberance is more obtuse than in the fore- 

 going specimen, but retains sufficient of the distinctive character of the 

 bone as compared with that in the genus Elephas. 

 From the tertiary formations of Ohio. 



752. The vertebra dentata of the Mastodon giganteus. 

 From the tertiary formations of Ohio. 



733. A fourth cervical vertebra of the Mastodon giganteus. 

 From the tertiary formations of Ohio. 



Purchased. 



Purchased. 



Purchased. 



