1879.] NATURAL SCIENCES OP PHILADELPHIA. 183 



One of these exhibits the following characters : there is a well- 

 developed marginal lobe of the posterior cutting edge of the third 

 and fourth premolars as well as a low posterior heel, and a rudi- 

 ment of an anterior one. The heel of the sectorial is shorter than 

 the remaining part of the tooth, and rises to a cutting edge a little 

 external to the middle line ; there is a small tubercle at its inte- 

 rior base. The anterior blade-cusp of the sectorial is much lower 

 than the median, which is conical ; the two diverge, diminishing 

 the shear-like character and action of the tooth. The internal 

 cusp is well developed. The first tubercular is of moderate size, 

 and is a longitudinal oval in outline. The crown supports two 

 low tubercles anterior to the middle, of which the external is the 

 larger. The last molar has a single compressed root, and the 

 ci'own is a longitudinal oval in outline. Its position is on the 

 ascending base of the coronoid ramus, so that the crown is slightly 

 oblique. The masseteric fossa is profound and well defined ; its 

 anterior termination is below the middle of the second tubercular 

 tooth. The horizontal ramus is not robust, but is compressed, 

 and rather deep. 



Measurements of Mandible. m. 



Length along bases of posterior five molars . . .049 

 Length of base of fourth premolar . . . .011 



Elevation of crown 008 



Length of base of sectorial 018 



Elevation of crown of " 012 



Length of base of first tubercular 0075 



Width " " " 0050 



Length of base of second tubercular . . . .0050 



While the characters of this dog do not separate it widely from 

 the genus Cants, many of them are quite different from those 

 presented by the recent species of the genus with which I am ac- 

 quainted. Thus the union of the foramina spheno-orbitale and 

 rotunda, the anterior position of the orbits, and the postorbital 

 constriction are not seen in the wolf, domestic dog, coyote, jackal, 

 or the North American and European foxes. The size of the 

 brain was evidently less than in those species, and the sectorial 

 teeth quite inferior in the efficiency of their blades. These cha- 

 racters may be considered in connection with the low geological 

 position of the beds in which the species occurs. 



