” 
1883,] 323 [Cope. 
second the shorter and wider, as in the known species. The first molar 
differs from that of both the latter, in having the tubercles of one side sepa- 
rated nearly to the base. These tubercles are conic, and not flattened 
in OQ. foliatus and O. pollua, and the two rows are separated by a distinct 
valley, as in the first named. There are five tubercles on one side, and four 
on the other side of the crown, and in addition, two small cusps at ule an- 
terior extremity of each row, and another at the posterior extremity of one 
of therows. These additional cusplets are not present in the other species. 
The jast molar is relatively wider than in the other species. Its crown 
is a good deal worn, but there are probably more than two rows of tuber- 
cles, as there are some appendicular rows on one side of the crown at least. 
Measurements. M. 
Diameters M, if ®Mteroposterior.............c.cee e008 10185 
/ |) Utransverse........ 5. THN Ne eb Ki sien OUOD 
. 3; § anteroposterior... .. i RANE NC ua Salat .0090 
Diameters M. ii ; ae 
UPHMSVCTSGN Ii dehe WN aleurlatensnnieh faiccs wine 00% 
The Upper Puerco; D. Baldwin. 
GENERAL REMARKS ON THE CHARACTERS OF THE MAMMALIA OF THE 
Punproo Erocn. 
I have already called attention to the fact that the Mammalia of the 
Puerco epoch possess, with but few exceptions, superior molar teeth whose 
crowns include only three of the component tubercles of the normal 
mammalian moiar, in a condition of full development.* In the number 
of species of supposed pl 
of species (1), with qu: 
being 
acentals now known, sixty-seven, the proportion 
idrituberculate superior molars is even smaller, 
only four to sixty-three. The premolars display equally primitive 
characters, and to these I wish now to draw attention. 
2. The presence of two internal tubercles of the fourth superior pre- 
molar is unknown as yet in the fauna. 
3. The presence of two external cusps of the same tooth is known or 
inferred in only five species in the sixty-seven, and in two of the five it is 
of reduced size. 
4. The presence of one 
internal cusp of the fourth superior premolar is 
demonstrated or inferr 
ed in all of the placental species, 
5. The presence of the internal cusp of the third superior premolar is, 
on the other hand, only demonstrated in twenty-two species. In seven- 
teen it is wanting. 
Referring to the inferior premolars : 
6. No species presents an internal cusp of the third premolar. 
7. An internal cusp of the fourth premolar is present in only fourteen 
Species. In twenty-nine species it is certainly wanting. . 
* Proceedings of the 
American Philosophical Society, 1883, 562. American 
Naturalist, 1888, 407, 
