24 
PROCEEDINGS OE THE ACADEMY OF 
veloped ; and the upper part of tlie ramus is more strongly depressed ex- 
ternally than in the Lama (Auchenia). The body of the lower jaw is relatively 
deeper than in the Camel, though not so robust ; and the two sides are coossi- 
ned by a comparatively short symphysis. 
Six molar teeth form a closed row in the lower jaw, being two additional to 
the number in the Camel and Lama. The true molars and the last premolar 
have nearly the same form as the corresponding teeth of the Camel. The 
second premolar is a reduced one from that behind it ; and the first premolar 
has a laterally compressed ovate crown implanted by two fangs. 
In a small fragment of a lower jaw, in the middle of the hiatus, in advance 
of the closed row of molars, there is the fang of a tooth, which appears to 
have been a caniniform premolar. The mental foramen is just in advance 
and below the position of this tooth. A foramen likewise exists below the 
third premolar of the closed row of teeth, corresponding to that more posteriorly 
situated in the Camel and Lama. 
Two mutilated but connecting fragments of an upper jaw present the hard 
palate more deeply arched than in the Camel or Lama ; and the face narrows 
in advance of the molar teeth as in the latter. A palatine foramen exists 
opposite the interval of the second and third premolars. The infra-orbital 
foramen occupies the same relative position as in the Camel. 
As in the lower jaw, six molar teeth form a closed row in the upper jaw. The 
true molars, though much mutilated in the specimens under examination, 
appear to possess the same form as those of the Camel. The last premolar is 
also like the corresponding tooth of the latter. The second premolar is like 
the first one of the Camel, with the exception that it has the antero-internal 
fold of its crown as well developed as the posterior fold, which it joins at the 
base. The first premolar is like the first one of the series in the Lama, having 
a trilobate, flattened, oval crown. 
Height of the ramus of the lower jaw, from its 
base to its condyle, 4 inches 10 lines. 
Depth of lower jaw below last molar, 2 " 
Distance from last molar to the end of the poste- 
rior coronoid process, 4 " 
Depth of lower jaw at middle of the hiatus of the 
teeth. 
Breadth of face in advance of upper molars, 
Breadth of face at back molars, 
Length of upper molar series, 
Length of lower molar series 
Length of upper true molar series, 
Length of lower true molar series 
Megalomeryx niobrarensis, Leidy. 
This genus and species are proposed on two lower molar teeth, in the Nio- 
brara collection, which indicate a ruminating animal of the largest size. One 
of the specimens is apparently a first true molar, and is inserted into a frag- 
ment of the jaw by a pair of strong fangs. The crown is two-thirds worn away, 
and presents the same form as the corresponding tooth of the Sheep in the 
same condition. The antero-postero diameter of the crown is 21 lines ; the 
transverse diameter 11^ lines. 
The second specimen is an isolated, nearly unworn, first or second true 
molar, witli the form nearly the same as in the corresponding teeth of the 
Sheep. Its length is three and one-third inches ; its antero-posterior diameter, 
at the triturating surface, is two inches, and just above the developing fangs 
an inch and a half; the transverse diameter, in the former position, is seven 
lines, and in the latter nine and a half lines. 
Merycochoerus proprius, Leidy. 
The genus and species are based on several halves of upper and lower jaws 
[March, 
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