126 DISTINCTION INTO SPECIES. 



Mastodon The representation given by the distinguished traveller, D'Orbigny, 



Andium. 



of the ultimate molar in Mastodon Andium, very closely resembles the 

 Baltimore tooth. The number, direction, and form of the mammillae are 

 nearly the same. Both the teeth have an anterior and posterior talon : 

 in both, the anterior talon is very small ; and the posterior, consisting of 

 two tubercles, considerable. The general form of the two teeth is quite 

 similar ; on the other hand they differ in that the Baltimore tooth has two 

 papillae between the ridges, while the Andium of D'Orbigny has three. 

 The cusps in the former are inclined to the median groove ; in the latter 

 they are comparatively upright. If M. D'Orbigny is correct in the opinion 

 that his four-ridged tooth is an ultimate, it would, in my opinion, determine 

 the Baltimore tooth to be an ultimate, and not penultimate. 



MASTODON HUMBOLDTIUS. 

 Mastodon This species, named from the celebrated traveller who discovered it, 



Humbold- 



tius. has been considered by the highest authorities, viz. Cuvier, De Blainville, 

 Owen, and I believe Darwin, to belong, equally with the Andium, to the 

 species Angustidens. Since this opinion has received the sanction of such 

 authority, the number of specimens from South America has been greatly 

 increased ; and it remains to be seen whether the inspection of these fossils 

 will lead to a change of opinion. 



In the remarks already made on the subject of the Mastodon Andium, 

 we have shown, the difference between the worn surfaces of Mastodon 

 Andium and Mastodon Humboldtius. To these we should add another 

 difference in the rostrated extremity of the lower jaw being shorter in the 

 Humboldtius. There were some other points which, at the time of my- 



