1896.] NATURAL SCIENCES OF PHILADELPHIA. 389 



No. 3 (with canine). m. m. 



Length of dental series ; 31 



Length of true molars and Pm. 1 ; 21 



Length of M-t; v 11.5 



Depth of ramus at M. y ; 8 



This species represents a section of the genus distinct from M. 

 mephitica, with which it is connected by M. orthostichus Cope. 

 Mephitis orthostichus sp. nov. 



This species is represented by superior first molars of five individ- 

 uals and mandibular rami of two others. Unfortunately in no case 

 are inferior and superior dentition of the same individual preserved 

 together. In one individual both rami are preserved. 



This species is intermediate in size between M. mephitica and M. 

 putorius, and resembles the latter species in the small raetaconid. 

 It resembles M. mephitica in the rising inferior outline of the man- 

 dibular ramus, and differs widely from both species in the character 

 of the superior M. i 



The superior M. i instead of presenting two parallel longitudinal 

 crests, has a slightly curved crest representing the paraconule, 

 which reaches a trihedral cusp, the metaconule. Thus is produced 

 an internal longitudinal crest which presents a convexity anteriorly 

 and an angle posteriorly, and an entrant angle between the two. 

 The protocone is a mere cingulum which rises to the apex of the 

 metaconule, and extends no further, so that there is no posterior 

 ledge as in the existing species. AVhile the internal crest is quite 

 different in its zig-zag character from that of 31. fossidens, the species 

 further differs from the latter in the inferior premolars which do not 

 overlap, and in the inferior size. The posterior border of the M. f 

 is not so deeply notched as in M. fossidens. 



The inferior dentition does not differ from that of M. mephitica 

 except in the small metaconid and entoconid, and the flatter pos- 

 terointernal face of the Pm. 1, in which it resembles M. fossidens. 

 The third premolar is in contact with the canine, and has two roots 

 which do not overlap those of the second. The crown is longer 

 than either and has a heel with a recurved rim. The third has the 

 same, while the fourth is a narrow heel, with a recurved rim all 

 around it. In no specimen is the angle of the mandible preserved. 



Measurements. m. m. 



No. 1 ; superior M i 



T.- . f anteroposterior ; 8 



Diameters, i x ^ / \ ^\ c 



transverse (greatest) 8 



