202 BULLETIN 169, UNITED STATES NATIONAL MUSEUM 



riQUEE 50.—MetacliTiacus provocator Simpson, U.S.N.M. no. 9278, left lower jaw: a, Grown view; 6, internal 



view. Twice natural size. 



FiQUEK 51.— Metachriacus provocator Simpson: a, U.S.N.M. no. 15126, left M2-3, crown view; 6, U.S.N.M. 

 no. 9259, right lower dentition, crown view. Twice natural size. 



Figure 62.— Metachriacus provocator Simpson, U.S.N.M. no. 9259, left M»-', crown view. Four times 



natural size. 



The difference from M. punitor is so obvious that its significance 

 requires no proof. In every case the deviation between the means is 

 significant, and in the available samples the observed ranges overlap, 

 barely, only for the widths of P4 and Mi. 



