VERTEBRATE REMAINS, PORT KENNEDY BONE DEPOSIT. 217 



Of the long bones of the limbs none are preserved but two tibise of adults. 

 These are about one-third smaller than that of M. jeffersonii. Associated with 

 other lots of bones are the distal parts of two other tibise of adults of the same size 

 as the first mentioned. All of these differ from the one figured and described by 

 Leidy, in the greater prominence of the internal maleolus, and the greater width 

 and depth of the groove separating it from the astragalar facet on the posterior face. 

 Without more material the value of this character is uncertain. 



Dimensions of tibia. 



mm. 



Greatest length ; 345 



External length ; 282 



Width of head (oblique) ; 175 



" of distal extremity (oblique) ; 141 



" of shaft at middle (transverse) ; 62 



-rv , t j. i j .-i • of anteroposterior; 71 



Diameters, distal end tibia no. I < , i -, Afx 



{ transverse ; 140 



-rv , , ! r- , c of anteroposterior ; 60 



Diameters, astragalar iaeet of no. I < , L 0A 



° ( transverse ; 80 



Dimensions of astragalus. 



No. 1, anteroposterior diameter ; 109 



anteroposterior; 78 



76 



Depth of fibular facet at middle ; 25 



Vertical diameter of navicular surface ; 45 



No. 2, anteroposterior diameter ; 84 



T.. r. , , , f anteroposterior ; 63 



Diameters of trochlea if. 5g 



Depth, fibular facet at middle ; 29 



Vertical diameter of navicular facet ; 35 



Bones obtained by Prof. Safford and Mr. H. 0. Mercer from the Big Bone Cave, 

 Tennessee, indicate the superior size of M. jeffersonii. They also demonstrate the 

 later period of the existence of the latter, since many of the bones still exhibit the 

 articular cartilages in place, somewhat shrunken and very hard. 



Megalonyx tortulus Cope, Proc. Am. Phil. Soc, 1871, p. 84, fig. 12. 



- This species is represented in the Wheat-ley collection by a single superior 

 canine molar. In the Academy collection are five superior canine molars of the 

 same type, and four inferior canine molars of the same general characters. There 

 is a nearly complete set of teeth of a young individual of probably the same species, 

 and the posterior three superior molars of a probably adult animal in place. 



Megalonyx tortulus is much smaller than M. wheatleyt, and the canine molars 

 have some marked peculiarities. The internal bulge of the superior canine molar 

 is more prominent than in either of the other species, and, as in M. wkeatleyt, is 



28 JOUEN. A. N. S. PHILA., VOL. XL 



