VERTEBRATE REMAINS, PORT KENNEDY BONE DEPOSIT. 233 



this species have, however, been found, so that the reference cannot be certainly 

 made. Of the extinct species, M fossidens a little exceeds M. mephitica in dimen- 

 sions, while M. obtusatus is considerably smaller than M. putorias. 



Mephitis fossidens Cope (PI. XVIII, fig. 7).- Proc. Acad. Nat. Sci. Phil , 1896,'p. 386. [Type No. 69, Mus. 

 Acad. Nat. Sci. Phil] 



This species is represented by parts of the jaws with teeth of eight individuals. 

 In only one of these do superior and inferior molars occur together, and this one is 

 therefore regarded as the type. The species is of the same size as M. mephitica, 

 and was supposed at first to be identical with that animal, until further study 

 revealed several important differences. 



The peculiarities of the dentition have been already pointed out in the synopsis 

 of species. These are found in the relations of the paraconule and metaconule of 

 the in 1 ; in the small metaconid of the inferior sectorial ; and in the overlapping of 

 the premolars. The character of the m 1 is seen in three specimens, of the 

 anterior premolars in one ; and of the inferior sectorial in six. The anterior portions 

 of the mandibular rami are often injured, and the canine teeth are preserved in 

 only two examples, and the incisors in none. 



The inferior molars resemble those of M. mephitica, but differ in the following 

 points : — The metaconid is much smaller, resembling that of M. putorius. The 

 entoconid is small and low. The pm. 1 has a flat face presenting backward and 

 inward, and bounded by a ridge on the external side. This face is rounded in 

 M. mephitica. The overlapping of the pins. 2 and 3 does not occur in the latter. 

 The inferior border of the ramus rises gently from below the posterior part of the 

 m T . The angle is prominent and the condyle occupies a position inferior to that 

 seen in Mephitis mephitica and M. putorius, in the two jaws in which this part is 

 preserved. It does not rise above the level of the molars as it does in M. mephitica. 



The ml is the most characteristic part of the dentition. The crown is traversed 

 by two parallel anteroposterior crests ; the external consisting of the paracone and 

 metacone, and the internal of the paraconule and metaconule. The posterior border 

 is deeply notched between the two, and the anterior border less so. The protocone 

 is represented by a cingulum, which occupies the anterior half of the interior base 

 of the crown, enclosing a fossa with the paraconule. Its border then rises vertically 

 to the inner longitudinal crest, which it joins about the middle. Just exterior to 

 this crest is a small tubercle, which may represent a metaconule. An external 

 cingulum, except at the base of the metacone. No anterior nor posterior cingula. 



In the existing species of Mephitis the protocone is continued into a wide ledge 

 round the posterior side of the crown as far as the base of the metacone. The 

 paraconule is V-shaped and does not reach the posterior part of the crown. 



Measurements, No. 1. 



mm. 



j,. , f 1 ] anteroposterior (greatest) ; 8 



( transverse ; 9.5 



Length of inferior sectorial; . 11 



Depth of mandibular ramus at m T ; 6 



40 JOURN. A. N .S. PHILA., VOL. XL 



