T^NIODONTA. 193 



Measurements. 



M. 



Width of enamel of large incisor 018 



Length of shaft of cylindric tooth 041 



Diameters of grinding surface of cylindric tooth \ anteroposterior Oil 



(transverse 010 



T^NIOLABIS Cope. 



American Naturalist, July (June), 1882. 



Established on a tooth whose position is on the arc of the alveolar 

 line which connects the molar and middle incisor regions. It is probably 

 either the third incisor of the superior or inferior series, or canine of the 

 inferior series. In either case it differs from the corresponding tooth of any 

 of the known genera of Tillodonta or Tceniodonta. The long diameter of 

 the root being placed anteroposteriorly, that of the crown makes with it an 

 angle of 30°. 



Section of crown oval; the grinding surface scalpriform in the manner 

 of a rodent incisor; but bevelled on one side of the long diameter instead 

 of on the end, as in that order. Enamel consisting of a wide band on the 

 external side of the tooth, which embraces more of the circumference near 

 the apex than elsewhere. Apex grooved behind. 



If this be an inferior canine tooth it differs from that of the Tillodonta 

 in its large size and incisor-like form. It most resembles the external or 

 third inferior incisor of Calamodon. From this it differs in the scalpriform 

 wear, and the oval instead of triangular section, and in the absence of 

 cementum layer. 



T^NIOLABIS SCALPER CopC. 



American Naturalist, 1882, July (June). 



Plate XXIII d ; tig. 7. 



The enamel band does not cover the entire width of the external face, 



but leaves a part of the dentinal surface anterior and posterior to it, except 



at the apex. At the latter point there are seven coarse shallow grooves of 



the enamel surface; and the posterior of these split up below, and become 



narrower, while the anterior run out at the more oblique anterior edge of 



the enamel band. The posterior apical groove has a flat bottom. At the 



front of the apex the enamel is involute to the inner side for a short dis- 

 13 



