36 



TRANSACTIONS OF THE WAGNER FREE 



The three teeth above indicated, from their association with the bones 

 just described, and from their relation with others previously referred to 

 Mylodon Jiarlani, are regarded as also belonging to this species, the den- 

 tition of which is yet imperfectly known. 



One of the specimens accords in form and size with the third molar 

 contained in the fragment of a mandible, from Big-bone-lick, Kentucky, on 

 which the species was originally established, represented in figures i, 2, 

 plate XIV., of "A Memoir on the Extinct Sloth Tribe of North America," 

 by the writer. It also accords in character with an isolated tooth of the 

 Mylodon harlani, from Missouri, referred by Dr. Harlan to Oryctcrotherium 

 inissouriense, represented in figs. 3, 4, plate I., of the American Journal of 

 Science and Arts for 1843. 



The triturating surface of the tooth, the greater part of its extent, forms 

 a horizontal plane, worn off in a short slope at the inner fore and outer 

 parts and with a concave pit on the inner lobe. The breadth of the tooth 

 at the middle obliquely from without forward and inward is 28 mm. ; the 

 fore and aft breadth of its inner lobe 24 mm. and of its outer lobe 14 mm. 

 At the constriction between the lobes it is 12 mm. 



A second specimen accords in form and size with the first lower molar 

 retained in a fragment of the mandible of Mylodo?t harlani, from Missouri, 

 represented in figure 2, plate III., of Dr. Harlan's description above indi- 

 cated. The tooth is reniform in transverse section, and in this respect 

 accords with a fragment of the tooth in the mandibular specimen on which 



the species was first established. The 

 biting extremity is remarkably dif- 

 ferent from that of the corresponding 

 tooth of Mylodon robustns, as repre- 

 sented in the plates of Prof Owen's 

 memoir, in which it ends in a single 

 slightly oblique plane. In the speci- 

 men under consideration, as repre- 

 sented in figure 3, plate V., and in the 

 subjoined woodcut, it forms an acute 

 pyramid, from the apex of which a 

 sharp crest extends inward and 

 downward ; and from the crest a 

 plane slopes downward and forward, 

 and a steeper, longer and curved 

 surface descends behind ; so that the tooth resembles more the tooth of the 

 living two-toed Sloth, Unan, than that of the Mylodon robustus, or the more 

 posterior molars of the species to which the tooth belongs. 



The remaining tooth, regarded as a first upper molar of Mylodon ]iai'la7ii, 

 figure 4, plate V., is also remarkably different from the corresponding tooth 



1 2 



First lower molar tooth, Mylodon harlani. 

 outline of upper extremity ; 2, transverse section 



