l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I23 



anterior edge of the paracone and passing slightly upward to near 

 the inner base of the protocone. The protocone is larger than the 

 paracone. The occlusal surfaces of the cusps are separated by a very 

 shallow anteroposterior valley. With slight wear a broad, pronounced 

 anterocrest (paracone-protocone crest) would be developed. A dis- 

 tinct transverse valley separates the paracone and protocone from 

 the metacone and hypocone. The valley is slightly deeper on the 

 labial side and broadens between the median edges of the cusps. The 

 metacone is slightly larger than the hypocone and is the size of the 

 protocone. A distinct conule on the anteromedian base of the hypo- 

 cone helps to close the valley between the hypocone and the metacone. 

 The posterior cingulum is much better developed than the anterior 

 cingulum. It forms a part of the posterior occlusal surface of the 

 hypocone and swings upward, joining the metacone near the lingual 

 edge about midway up the cusp. Between the posterior edge of the 

 accessory conule and the posterior cingulum is a shallow pit. With 

 wear, a broad posterocrest (metacone-hypocone crest) would develop. 

 It appears that with further wear the two crests would join first on 

 the lingual side, giving a broad U-shaped pattern. Then with further 

 wear the crests would soon join on the labial side leaving a shallow 

 enamel pit between the median edges of the cusps. 



M^ is nearly square in outline. It consists of four large distinct 

 cusps, the paracone, protocone, metacone, and hypocone. The an- 

 terior cingulum is well developed, and therefore more pronounced 

 than the posterior cingulum. The cingulum joins the paracone at the 

 anterolabial edge and does not reach the occlusal surface of the cusp. 

 The cingulum passes nearly horizontally across the anterior surface 

 of the tooth to join the protocone slightly beyond the midline. Be- 

 tween the cingulum and the anterocrest is a very shallow and narrow 

 valley. The paracone and protocone are but slightly separated in the 

 midline and would soon wear to a broad distinct anterocrest (trans- 

 verse crest). The transverse valley between the anterior cusps and 

 the posterior cusps is deep. The median valley separating the meta- 

 cone and hypocone is deeper than that separating the paracone and 

 protocone. With wear, a distinct posterocrest would be developed. 

 The tooth then would develop, with further wear, the same pattern 

 as P *. If the accessory conule at the anteromedian base of the hypo- 

 cone is not considered, the protocone is the largest of the cusps of 

 M^, M-, and M^. The posterior cingulum is not pronounced and a 

 shallow pit is between it and the posteromedian bases of the meta- 

 cone and hypocone, M^ is the size of M^ and is like that tooth, except 



