20 Central Cavity of the Mastodon. [Jan., 



must have been much less curved than in man. The following 

 are the dimensions of the cranial cavity, 



Length of right side, ------ 7.6 inches. 



left " 8.2 " 



Depth from vertex to the opening of the 



foramen magnum, ------ 10.5 " 



Cuvier estimates the brain of the elephant at -g\^ of the whole 

 animal. The ratio would seem to be far less in the mastodon, 

 which, if not taller, was probably the bulkier creature of the two. 



The anterior lobes of the cerebrum must have been small and 

 much elongated, particularly on the left side, which extended .8 

 of an inch beyond its fellow on the right. The brain, therefore, 

 it is to be presumed, was not symmetrical. 



The posterior surface of the cranium was complete, and, with 

 the exception of the ligaments of the neck, exceedingly free firom 

 inequalities of any kind. Its elevation was nine inches, of which 

 by far the largest portion was due to a separation of the two 

 plates of the parietal bone. The space thus formed was filled 

 with a multitude of cells,* very various in size, and the whole 

 arrangement had doubtless been adapted to afford adequate inser- 

 tion of the muscles destined to support the enormous head and 

 tusks. Beneath the sockets of those tusks, it may be mentioned, 

 and rising at a quarter angle, are two long, oval hollows, the uses 

 of which are not very apparent. But as their contents must have 

 communicated with the tusks at their origin, to the formation of 

 these last they were probably subservient.f 



*The space has been ascertained in the head of the skeleton found about 

 the same time, in Orange county, and mounted by Dr. Prime, to be ll^ inches 

 (see last vol. of this Journal, page 209. — Ed.). 



t No communication between these cavities and the socket of the tusks 

 could be discovered in the skeleton which we recently arranged, and which 

 we examined carefully for this very purpose. For a full description of this 

 skeleton with a drawing, see last vol. of this Journal,,page 203. 



We noticed a remarkable difference in the size and length of these two 

 cavities, in the skull deposited with the Lyceum of Natural History by Dr. 

 Hulse. It would have beena curious question whether the corresponding 

 tusks exhibited any difference in size. — Ed. 



