FREE INSTITUTE OF SCIENCE 



MASTODON 



reduced to the rounded talon. Fore and aft it is nearly straight, but is slightly 

 bent, with the concavity inward. The anterior two 'pairs of lobes are nearly 

 equal, the succeeding pair is slightly reduced, and the fourth pair is reduced 

 about one-fourth. The inner lobes expand medially fore and aft into stout 

 buttresses, of which the contiguous ones conjoin in the valleys of the crown 

 and obstruct the middle of their course for more than half the depth. The 

 summits of the inner lobes, prolonged on their buttresses, are subdivided into 

 rows of tubercles. The anterior buttress of the first inner lobe is continuous, 

 with an equally strong tubercular ridge in advance of the position of the con- 

 tiguous outer lobe, producing a conspicuous feature of the front of the crown. 

 The posterior two inner lobes have their posterior buttresses nearly obsolete. 



The outer lobes of the crown, narrower than the inner ones, are medially 

 extended towards the latter rather than fore and aft, though in these positions 

 tubercles springing from their base and occupying the valleys are rudiments of 

 the buttresses of the inner lobes. The summits of the outer lobes are divided 

 into transverse rows of rounded tubercles. The summits of the pairs of lobes 

 are separated by angular notches, and deeper angular notches separate the sum- 

 mits of the inner lobes. In the second and fourth pairs of lobes the notches 

 are rendered shallower, from the development of a medial tubercular offset from 

 the contiguous inner lobe. The first outer lobe displays three eminences at its 

 summit ; the succeeding outer lobes, transverse rows of four eminences. 



The talon of the crown is a strong semicircular projection of the base, 

 from which springs a row of half a dozen unequal nipple-shaped eminences. 

 The basal ridge, especially thick at the inner front part of the crown, extends 

 interruptedly along the inner side and behind the talon, and is more conspicu- 

 ously marked at the entrance of the valleys. Considerable irregular cementum 

 occupies the deeper recesses of the crown. 



The measurements of the specimen are as follows : 



Diameter of the crown fore and aft . . . . .193 mm. 



Diameter of the crown transversely at the anterior lobes . 97 " 



Diameter of the crown transversely at the second lobes . 94 " 



Diameter of the crown transversely at the third lobes . . 87 " 



Diameter of the crown transversely at the fourth lobes . 80 " 



Height of the first inner lobe . . . . . . 82 " 



Height of the second inner lobe . . . . . 80 " 



Height of the third inner lobe . . . . . 73 " 



Height of the fourth inner lobe . . . . . . 65 " 



