Cope. ] 484. [Sept. 19, 
of two lobes. The posterior molar had no more lobes, and is smaller 
than the penultimate. The first is two-rooted, and is separated by a wide 
space from the inferior canine. The superior canine is of disproportion- 
ately large size, and issues a little behind the premaxillary suture.~ The 
incisions are crowded closely together, and are of conic form. The ex- 
terior is several times as large as the others. The inferior incisors are of 
huge size, project upwards after the manner of rodents, and are inserted 
by a short base into the solid symphysis. They are separated by a short 
interspace, which is without alveoli. 
The fore foot possesses four digits, of which the inner is considerably 
the shorter. Phalanges not slender ; ungueals flat, deeply fissured above. 
Caudal vertebra slender. 
This most remarkable genus is not at present. referable to its proper 
order, The superior anterior teeth are of carnivorous type; the opposing 
teeth look like those of rodents, while the molar teeth differ from both. 
It is allied to Anchippodus, Leidy, which is only known from mandibles. 
This form Dr. Leidy has called the “onawing hog,’’ but, as it probably 
exhibits a structure similar to that seen in the present genus, it is obvi- 
ous that the huge symphyseal teeth were not designed for gnawing in 
the usual sense. I suspect these animals to have lived largely on turtles, * 
and that the structure in question was adapted for crushing their shells. 
This is the more likely from the prodigious number of turtles which must 
have existed contemporaneously with them. There are twenty species 
described from the Bridger formation, and their numbers are legion, as 
already described by Professor Marsh. Their bones are alw: ys in sight, 
and six or eight are not unfrequently found lying together. 
Char. specif. The mandibular rami, posterior to the symphysis, are not 
heavily constructed. The symphyseal teeth are very stout, and exhibit 
two longitudinal grooves on the outer and outer inferior face; the shaft is 
compressed, and the worn surface is on the outer side, as produced by 
the canines, and on the extremity, produced by the outer incisor. The 
superior canine is compressed, and as large as that of a grizzly 
bear. The outer incisor is nearly straight, and with conic crown. A 
large part of its shaft is exposed at the bottom of a wide vertical 
groove, which extends upwards between the canine tooth and a ridge de- 
scending from the edge of the nares. The external nareal opening is en- 
tirely anterior, and is narrowed below, in accordance with the narrowing 
of the premaxillaries. 
M. 
Length of interior dental series to bases of symphyseal 
HQOUM a os es A. vas erie a ar OE ae err 0.170 
Depth ramus at last molar........ id tha dapat aver Fees 050 
Length symphysis... 06.0% iba coe ea MDE rae A 060 
Cee OIA: ARON CAIITO asd cacy os FUME Ree ines Ail 
Length symphyseal tooth projected........ Halles oo eee LO) 
Diameter & a + ina caren od ous MORO 
a canine ef = Sepia Hutwees nay 6028 
* This view was already expressed in The Friend, Philada., 1872, Winter 
