american mastodon. 209 



Anatomy of the mastodon. 

 The skull. The bones of the skull are wonderfully large, and as 

 well preserved as the other bones. The posterior part is flat and 

 broad, measuring in height one foot eleven inches, and in width two 

 feet nine inches. The foramen magnum for the passage of the spi- 

 nal marrow, is three inches and a half in diameter. In the centre of 

 the occipital bone are two deep cavities for the insertion of the 

 ligamentum nuchcB, separated by a thin bony partition. The frontal 

 bone is two feet four inches wide, between the orbits of the eyes. 

 The outer plate of bone is very hard and three quarters of an inch 

 thick, where we find eleven inches and a quarter of cellular bone, 

 extending down to the brain. The cavity of the brain is small, oc- 

 cupying only the lower portion of the skull. In front of the nares 

 (nostrils), between the origin of the tusks, is a cavity as large as 

 that of the brain, and is probably the antrum highmorianum. 



The insertion of the tusks into the intermaxillary bones, is two 

 feet five inches, extending quite back of the orbits. These tusks 

 were ten and a half feet in length, and two feet and an inch in cir- 

 cumference where they enter the socket. With regard to the direc- 

 tion of the tusks, we are convinced from observation of a number 

 of skulls, that their direction is as accidental as the horns of cattle. 

 Some follow the first curve, downward and outwards, the points in 

 one which we have seen being eleven feet asunder. In the skull of 

 this skeleton before us, they first curved downwards and outwards 

 till they were seven feet apart, when they curved inwards and 

 slightly upwards till they approached at the points within two feet 

 gf each other. The socket of the tusks is curved and flattened so 

 that it was impossible for the tusks to have turned in the sockets, 

 during the decay of the soft parts, as is supposed by many to have 

 been the case. 



The whole skull, lengthwise, is bounded on all sides by nearly 

 Straight lines. The lower jaw is nearly straight from the angle to 

 "Ithe front, and measures in that line two feet ten inches. The con- 

 ' Idyloid process by which it is articulated with the head, is distant 

 ifrom the coronoid process one foot. In the front of the lower jaw, 

 at the commissure, is a small round tooth, eleven inches in length 

 and one inch and a half in diameter, and inserted into a socket seven 

 inches deep. This is on the left side of the commissure. On the 



