48 



DESCRIPTION OF AN ENTIRE HEAD, ETC., OF THE MASTODON. 



Wherever examined, this clay seems to be destitute of organic remains. The 

 shale is part of the formation which extends from the Ohio river to Lake Erie. 

 The limestone is generally destitute of fossils. The following sketch repre- 

 sents the geological structure of a portion of Crawford county, and exhibits 

 the position in which the bones were found. 



A, limestone. B, shale. C, sandstone. D, blue clay. E, 

 ^ yellow clay, a, bed of fresh-water-shell marl, in which the 

 ]3 bones were found, b, b, Sandusky river, crossing twice the 

 A above profile, extending from east to west. 



The fresh-water-shell marl, being deposited in the yellowish clay, is more 

 recent than the latter, and therefore, as Mr. Briggs observes, " the Mastodon 

 has become extinct since the deposite of the materials upon the surface of 

 which are our magniJEicent forests and beautiful prairies." Thus confirming 

 the opinion expressed by the committee, as to the comparatively very recent 

 period at which this animal became extinct. 



It is proper to state, also, that a brief notice of these bones, with a profile 

 sketch of the head, was communicated to Professor Silliman by Mr. J. W. 

 Foster, and have been published in the American Journal of Science and the 

 Arts, Vol. XXXVL, p. 189. 



