THE BALTIMORE TOOTH. 81 



ridge and talon, but are much worn in the first, second, and third; each 

 presenting, with different degrees of distinctness, a trifoliate appearance. 

 The edges of the worn enamel exposed are between one and two lines in 

 thickness. The unworn nipples, that is, of the fourth ridge and the talon, 

 are remarkable for their mammillated and rounded form ; while the unworn 

 nipples of 1»he Mastodon Giganteus have a flattened or wedge-like form. 



Another point in which this tooth differs remarkably from those of the Distinct 



from 



Mastodon Giganteus consists in certain minor eminences, situated between Mastodon 



Giganteus. 



the ridges ; two of these smaller eminences, or papilke, lie between each 

 of the ridges, though imperfectly developed between the last two. Those 

 between the two anterior ridges are partially worn ; those between the 

 posterior, not being so prominent, have not been exposed to attrition. The 

 basal ridge is less distinctly indicated than in the Mastodon Giganteus. 

 The lateral surfaces have four clefts, corresponding with the depressions 

 between the ridges. The fangs or roots of this tooth are broken off. The 

 cavities or hollows, with their septa, are very perfect. There are four pairs 

 of the latter, corresponding with the four pairs of mammillary eminences ; 

 and a fifth pair, very small, in the posterior cavities of the fourth pair, 

 answering to the cusps of the talon. These appearances show that the 

 animal was young. 



We perceive, then, that this tooth, like that of the Mastodon Angusti- nu 



stinct 

 from 



dens represented and described by Cuvier, is long and narrow, with inter- Mastodon 



Angusti- 



vening papillae. One principal difference between it and the casts of the d ens. 



Mastodon Angustidens tooth in my possession is in the division of this 



specimen into four ridges, and the others into three only ; a point in which, 



if we consider it to be a penultimate, it approaches more nearly a tooth 



of Kaup's Mastodon Longirostris than one of the Mastodon Angustidens. 

 11 



