SCOTAMYS 193 



of two laminae separated by a deep external fold, around 

 the inner end of which the laminae are connected by a 

 narrow bar. In the present condition of wear there is no 

 indication of secondary furrows. The premolar is smaller 

 than the molars. 



MEASUREMENTS SPECIMEN 3063 



Lower dentition, in. I to pm. 4 8 mm. 



Lower dentition, premolar 4 length 3 mm., width 2.5 mm. 



Lower dentition, molar I length 2.5 mm., width 2.5 mm. 



Lower dentition, molar 2, length 2.75 mm., width 3 mm. 



Height of mandible under pm. 4 5.5 mm. 



Fig. 126. Left mandible external side, x 4/1. 



Litodontomys gen. nov. 



One set of lower teeth found by the Amherst party 

 shows a simplicity of pattern found in no other genus of 

 South America; and this is, therefore, named Litodontomys. 

 The teeth are brachydont, the premolar and the molars 

 each being divided into two laminae by an external and 

 an internal fold, the distinctive generic feature being in 

 that this fold is narrowest at the margin of the tooth and 

 expands internally. In connection with the expanded 

 folds, the ends of the laminae are curved toward each other, 

 so that in a worn specimen they would meet on the margins 

 of the tooth, and leave the folds to appear as pits. No 

 indication of a furrow is evident on either lamina. 



