VERTEBRATE REMAINS, PORT KENNEDY BONE DEPOSIT. 215 



the apex. From these specimens we learn that the malar bone in Megalonyx 

 differs from that of Mylodon in the presence of the slender postorbital process and 

 in the more slender and acute suborbital process. In most of the Mylodons it is 

 fan-shaped, but in the genus or group Lestodon it is narrower, approaching the 

 acuminate form seen in Megalonyx wheatleyi. 



A fragment of a right maxillary bone contains the four true molars and the 

 canine molar. The proportions are much as in the M. jeffersonii figured by Leidy. 

 The only perceptible difference, excepting the inferior size, is in the form of the first 

 and last true molars. The crowns are less in fore and aft diameter than in the 

 larger species. This is, however, probably only an individual peculiarity. The 

 lower jaw of the same individual is represented by most of the right ramus and a 

 part of the left. The posterior parts of the former are broken away and all the 

 teeth are preserved. The only character which distinguishes this jaw from that 

 one of M. jeffersonii described by Leidy, is that the symphyseal keel is more promi- 

 nent, and the mental foramen relatively smaller. The former projects in front of 

 the canine molar as far as the anteroposterior diameter of that tooth, while in 

 M. jeffersonii 'it projects only three-fifths the diameter of the canine molar in front 

 of it. The mental foramen is quite small. Whether these characters are constant 

 or not must be determined hereafter. 



Measurements. 

 No. 1 — Both jaws and part of skull. mm. 



~. ,, r • ■ -i \ anteroposterior ; 34 



Diameters ot crown ol superior canine molar % , L 1P 



1 [ transverse; lb 



_.: r. n . r • • if anteroposterior ; 35 



Diameters ol crown ol interior canine molar < , -, r 



( transverse ; 1 5 



-p.. n 3 j anteroposterior ; 13 



{ transverse, greatest ; 20 



t^. r. . ( anteroposterior; 10 



Diameters of m A < r , 7 



( transverse ; 1 / 



Depth of ramus mandibuli at posterior external foramen ; 48 



No. 4 — Crushed skull without muzzle. 



Width at occiput; 148 



Length from occiput to posterior border of orbit; 194 



Depth of zygoma at glenoid cavity ; 42 



" " at malar bone ; 31 



tv , , i , f anteroposterior at orbit ; 42 



Diameters at malar bone < , . \ 208 



Length of postorbital process of malar ; 39 



" of infraorbital " " 69 



Length of mandibular ramus from posterior external foramen to apex 



of angle; 132 



Depth of mandibular ramus at posterior external foramen ; 69 



" " " at condyle ; 111 



