MASTODON TETRACAULODON.- 133 



this country has deeply deplored. A great number of mandibles of the Mastodon 



Tetracau- 



Mastodon having been found furnished with one or more tusks, it was i don. 

 natural to consider its occasional existence as a peculiarity sufficiently 

 important to stamp it as a new species. 



The remarkable skeleton described in this paper having a mandibular 

 tusk on one side, and the remains of a very distinct fossa for the reception 

 of a second on the other, we must, of course, inquire whether the existence 

 of this part affords sufficient reasons for considering this specimen to have 

 belonged to an animal specifically different from the Mastodon Giganteus, 

 or whether it characterized the age or sex of the last-named species. 



The specimen from which Dr. Godman made his description was the 

 lower jaw of a young Mastodon, which he describes as being perfect on 

 the right side, " with the exception of part of the condyloid, the whole of 

 the coronoid, and a small part of the posterior alveolar processes " (Trans. 

 Am. Phil. Soc. p. 488). This is obviously a mistake, as his plate shows 

 that the greater part of the coronoid process is preserved, and none of the 

 condyloid ; and the cast of the same jaw in our possession agrees with 

 the plate.* Of course, the obliquity of the condyloid process, described by 

 him as peculiar to the Tetracaulodon, could not have been observed in 

 this jaw. 



This mandibular tusk is .represented to have been four inches long, and 

 its socket an inch in diameter at its outlet. On the left side was a 

 corresponding alveolar cavity without a tusk. These sockets are filled with 

 osseous matter as the subject advances in age, so that in the adult they are 

 generally obliterated, leaving vestiges of their previous existence. 



* Perhaps the terms condyloid and coronoid were accidentally transposed in printing. 



