ON THE TRITUBERCULAR MOLAR. IN| HUMAN 
DENTITION. 
E. D: COPE: 
Descriptions of the molar teeth of man, given by anato- 
mists, differ in important respects. Thus, F. Cuvier (‘ Dents 
des Mammifers’’) states that, while the crown of the first 
superior true molar consists of four tubercles, those of the 
second and third superior true molars consist of but three 
tubercles. In the American edition of ‘“Sharpey and Quain’s 
Anatomy” it is stated that the crowns of the superior true 
molars of man consist of four tubercles; and the same state- 
ment is made in Allen’s late work on human anatomy. 
My observations having shown me that both of these descrip- 
tions apply correctly to certain types of dentition, I determined 
to examine for myself, to ascertain, if possible, the extent and 
value of the variations thus indicated. My interest in the sub- 
ject had been especially stimulated by the researches among 
the extinct mammalia, and the results which I had derived 
from them. These are, in brief, as follows: first, the quad- 
ritubercular type of molar crown, illustrated by the first supe- 
rior true molar of man, belongs to the primitive form from 
which all the crest-crowned (lophodont) molars of the hoofed 
placental mammals have been derived; and second, this quad- 
ritubercular type of molar has itself been derived from’a still 
earlier, tritubercular crown, by the addition of a cusp at the 
posterior internal part of it. This tritubercular molar in the 
upper series has given origin directly to the superior secto- 
rial teeth of the creodonta and carnivora. In the inferior 
series, I have shown that in known placental mammalia at 
least, the primitive molar crown is quinquetubercular, or tritu- 
bercular with a posterior heel; that this form gave origin to 
the inferior sectorial tooth of carnivora by modification, and to 
the quadritubercular type — corresponding to the superior quad- 
ritubercular crown —by a loss of the anterior inner cusp and 
