DESCRIPTION OF PLAT EC I. 



F^G. 1. Skull of Sciurus niffer rufiventer, showing normal incisor growth. 

 Fig. 2. Skull of Sciunts niger rufiventer, (left side) showing abnormal 



incisor growth. 

 Fig. 3. Skull of Sciurus niger rufiventer, (right side) showing abnormal 



incisor growth. 



