26 E. L. Troxell — Amynodonts in Marsh Collection. 



surface of theiooth; the metaloph is very narrow, joins 

 the protoloph through the deuterocone, and surrounds a 

 central lake across which there is a very narrow bridge 

 or small fold of enamel. Because of the small metaloph 

 and the receded position of the tetartocone, the worn sur- 

 face of the tooth forms a triangle. 



P* presents equally strange characters : it is extended 

 transversely but is squeezed in between P^ and M^ so that 

 it is longer on the inner side than along the ectoloph. The 

 wide extension inward forms a gentle slope from the 

 deuterocone, but more especially from the tetartocone to 

 the cingulum. The metaloph is relatively larger than that 

 of P^ and widely separated from the protoloph. On the 

 right tooth, a sharp ridge, on the left a low broad one, 



r02 74 TYPE 

 Y P M 



Fig. 2. — Metamynodon rex, sp. nov. Holotype. Palatal view of skull 

 showing great reduction of premolars with P^ rotated, deep posterior nares, 

 heavy canine, and posterior extension of ectoloph on M^ X l/^- 



unites the two inner cones. There is a sharp crista divid- 

 ing the internal lake (medisinus), and numerous small 

 folds on the metaloph represent the crochet. 



The outer wall of the ectoloph on each premolar shows 

 a heavy central buttress set off by vertical grooves in 

 front and behind ; this represents the central protocone, 

 w^ith the tritocone and parastyle behind and in front 

 respectively. 



M^ is so worn that no characters remain except a 

 faint cingulum on the outer side, together with a small 



