324 A NEW MYLODON. 



19 mm., transverse 15, thus much the same as in M. harlani (see Cojie, 1895). 

 The beveled surface of the crown is 20 long. The tooth projects ahout 19 nun. 

 from the socket and is separated from the second by an interval of only 9 nun. 



The second upper toolh Ukewise has its anterior portion recurved so that the 

 crown is directed backward at a small angle to the palate. The front face is 

 sUghtly beveled by contact with the posterior facet of the first lower tooth, but 

 the crown opposes the second lower tooth. The general outline in section is 

 an ellipse, with a longitudinal diameter of 36 nun., transverse 17, at the alveolus. 

 The tooth figured by Cope (1895) as the second upper molar of M. harlani is 

 similar but with a much greater bevel on the anterior face. 



The third upi)rr tooth has three lobes, an outer with nearly square outhne, 

 and two inner, of wliich the posterior is much tlie longer with nearly parallel 

 sides and rounded ends. A shallow sulcus separates these two lobes at the 

 lingual side of the tooth. The posterior lobe forms a long heel which is bent at 

 an angle of nearly 45 degrees from the axis of the tooth row toward the median 

 side. The outline is not essentially different from what Cope (1895, pi. 10) 

 figures for M. harlani and M. renidens; and as nearly as may be judged from a 

 photograph, the tooth is practically the same in the Colorado specimen. The 

 anterior inner lobe is about opposite the single outer lobe, but so deflected is 

 the posterior lobe that its tip is in the same straight line as that of the first. 

 The extreme breadth anteriorly is about 24 mm. ; \\\v l(>ngtli in the axis of the 

 tooth row from tip of the anterior iimer lobe to the back of posterior lobe is 

 29.6 mm., while the diagonal from the point of the latter to the tip of the outer 

 lobe is 33 mm. 



The fourth upper toolh is narrow and compressed in the long axis of the 

 toothrow, but is set at an angle of nearly 45 degrees to the latter. It has three 

 lobes, as does the preceding tooth, two inner and one outer, but the last is con- 

 siderably in advance of the anterior inner lobe; and the posterior inner lobe is 

 not much elongated, apparently much less so than in M. harlani and M. renidens, 

 as figured by Cope. In this respect the Colorado skull seems to resemble these 

 two species and to differ from our specimen. There is thus a greater dissunilarity 

 in the shape of the third and fourth upper teeth of our animal than appears in 

 the three others. So compressed is it, that its outline is roughly a parallelogram, 

 slightly concave on the posterior outhne. The dimensions are: — tip of anterior 

 inner lobe to tip of outer lobe 30 mm. ; from the latter point to tip of posterior 

 inner lobe 35.5 mm. ; front of anterior inner to end of posterior inner lobe 19 mm. 

 The fifth upper toolh differs decidedly from that of M. harlani and M. reni- 



