38 PROCEEDINGS OP THE ACADEMY OF [1886. 



lines of growth. They show no trace of the fluting in the tusk 

 of the hippopotamus, nor of the strong external ridge of the 

 peccary. The specimen is nearer in character to the tusk of the 

 hog than that of any other related animal, but is sufficiently dif- 

 ferent to render it probable that it may pertain to another genus. 

 No undoubted remains of the genus Sus have yet been discovered 

 in America, and the same is the case with the genus Hippopot- 

 amus. The peccary appears to be the American representative 

 of the hog. The fossil may provisionally be referred to a new 

 genus, related with the latter, with the name of JSusyodon, dis- 

 tinuuishing the species as Eusyodon maximus. 



The transverse diameter of the section of the tusk, about three 

 inches from the point, is an inch and two-thirds ; and the fore and 

 aft diameter an inch and a quarter. 



Caries in the Mastodon. Prof. Leidy directed attention to a 

 specimen consisting of the posterior portion of a last upper 

 molar tooth of the Mastodon, which he had attributed to a spe- 

 cies under the name of M. Jioridanus. It is remarkable from 

 the circumstance that it apparently exhibits the result of caries, 

 a condition of which he had never previously observed an instance 

 in extinct animals. The supposed caries appears as an irregular 

 excavation immediately above the crown of the tooth, about four 

 lines in depth. The mouth of the cavity is elliptical, extending 

 one and one-fourth inches transversely, and one-fourth of an inch 

 vertically. The surface of the cavity appears irregularly eroded. 



F. L. Harvey and Miss Mary A. Campbell were elected 

 members. 



The following were ordered to be printed : 



