1877.] 225 
(Cope. 
angular, the lateral faces being longer than the posterior, and the anterior 
angle is a narrow one. The surface of the enamel cannot be described, as 
it is eroded at some points. The diastema is long. 
The first (homologically second) premolar is narow, and is without 
lateral or posterior lobe or cingulum, but a third is a rudimental lobe at its 
anterior base. The heel presents an interior tubercle, and a narrow pos- 
tero-external lobe which embraces a medeo-external tubercle. The latter 
becomes the external posterior tubercle on the true molars. The third pre- 
molar is larger and wider than the second ; the medio-external lobe be- 
comes more external and posterior, and a median tubercle appears in front 
of it. The posterior tubercle still sends a narrow ledge round to the outer 
base of the medio-external lobe. The anterior lobes are more elevated 
than the others, and are only separated by a fissure. In the fourth premolar 
the true molar structure is seen in the regular quadri-tuberculate form. 
There is a small tubercle in front and behind the notch of lobes, and a fold 
descending forwards on the outer side of the external posterior lobe. In 
the second trué molar there is an additional tubercle on the middle line be- 
tween the pairs of lobes. The median accessory tubercles are not distinct 
on the last molar, excepting the posterior, which becomes a large heel. 
The lobes of each pair are not deeply separated on the last two molars. 
These teeth are rather abruptly larger than the first true molar, which is 
little larger than the last premolar. Each of them has a narrow anterior 
cingulum, but no other. The enamel is nearly smooth. 
Measurements. M. 
Length of mandible from end of posterior molar to in- 
GISLVE “ALV COT g ceosetieeis cis x 4s insia ove aie eacedvcarminminntacesdees 0.190 
Length of molar series.....--- 0. +s eee eee cece ee ees 108 
a {TUG MIONATS. Sic ss seewe ee aies doe see eas 062 
5 CASES 5 pains ea dines DORR Os Se RE 054 
Width between bases of canines...........0eeeeeeeeee 020 
“Of CiaStOMAls cv s.c0 trade ee eek See Eee 2. 024 
“© between bases of first premolars............... .082 
antero-posterior. ........e00.05 .012 
Diameter of p. m. 2 { tYANSVETSE. eee cece eee eee ee ee 007 
: tLANSVETSC.. 1... eee eeee sie Roe 015 
Diameter of p. m. 4 Lee wien: po eieiaecealems teas oat 012 
; antero-posterior. ......+-+..6+ee 021 
Diameter of m. 2 ‘ tPANSVELSE ios 2s sce ose Atees sees .016 
antero-posterior........0:0.+--- 026 
Diameter of m. 3. TYANSVETSC. 2. e eee eect eee eee 015 
The animal from which the above description was taken was adult. It 
was discovered in the Loup Fork beds of North-Western Kansas by Russell 
Hill of this city. 
TETRALOPHODON CAMPESTER sp. nov. 
The cranium and under jaw, with nearly complete dentition, including 
tusks, of this species, were obtained by my assistant, Russell 8. Hill. The 
PROC. AMER. PHILOS. soc. xviI. 100. 2c. PRINTED JAN. 12, 1878. 
