212 VERTEBRATE REMAINS, PORT KENNEDY BONE DEPOSIT. 



(/. c. fig. 1) belongs to M. wheat ley i. and represents very well the peculiarities 

 which distinguish it from M. jeffersonii. 



The tooth of M. loxodon is entirel}' convex on its internal face, being with- 

 out the grooves which characterize the other species. The greatest transverse 

 diameter is little nearer the posterior margin than the anterior, a character in which 

 it differs from both M. jeffersonii and M. wheatleyi. The external face is 

 slightly openly concave in transverse section, a character very exceptional in the 

 other species, and then usually caused by the presence of a shallow groove. The 

 size is that of M. wheatleyi, and less than that of M. jeffersonii. 



Measurements. 



mm. 1 



Diameters of grinding face \ ^ U U() l x,!s aior ' 

 ° ° { transverse ; 



Megalonyx wheatleyi Cope, Proc. Am. Phil. Soc, 1871, p. 75, figs. 1, 3-8. 

 Megalonyx dissimilis Leidy ; Cope /. c, p. 83 ; not of Leidy. 



The greater number of specimens of gaint sloths found at Port Kennedy belong 

 to this species. Besides the set of upper and lower molars of one side of a decayed 

 skull in the Wheatley collection, which served as the basis of the first determina- 

 ation of the species, the Academy collection contains the following, on which the 

 further definition of the species is possible. No. 1, all the teeth of both sides except 

 the left inferior canine-molar, in the crushed jaws. No. 2, molars and canine-molars 

 of one side in decayed and crushed jaws. No. 3, all the molars of both sides with- 

 out canine-molars. No. 4, a crushed skull nearly complete with all the teeth (canine- 

 molars uncertain) in decayed jaws. No. 5, a maxillary with all the teeth (accom- 

 panied by the greater part of the lower jaw with all the teeth ; besides other 

 decayed, and crushed jaws which exhibit more or less of the dentition of one or both 

 sides. These specimens render the identification of every tooth possible. 



As the first mentioned Academy specimen possesses the normal dentition, 

 although the skull is not the most perfect, I describe it first. 



The superior canine-molars are strongly curved in the anteroposterior plane, 

 first forward and the downward. They are slightly convex in transverse section 

 of the external face, without interruption by a groove or open concavit}^. The 

 longitudinal bulge of the internal face is nearer the anterior than the posterior edge 

 of the tooth, and on the surface connecting it with the former there is only a slight 

 trace of concavity. (In most other corrsponding teeth of this species this trace is 

 absent.) On the inner side of the bulge the transverse diameter contracts abruptly, 

 and the surface turning toward the border forms an open concavity or groove with 

 the bulge. The inferior canine-molars are flatter than the superior, and the greatest 

 transverse diameter is a little nearer the posterior than the anterior border of the 

 tooth. No concavity separates the low bulge from either border. In some other 

 specimens a very shallow groove separates it from the borders. The transverse 

 diameter at the posterior border is a little greater than that at the anterior. 



1 Blank in MSS. 



