FROM QUATERNARY DEPOSITS IN THE VALLEY OE MEXICO. 
75 
veloped, and the upper part of the ramus is more strongly depressed externally 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 co-ossified 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 \_p 2] has a laterally com- 
pressed 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 canini- 
form premolar \_p 1]. The mental foramen is just in advance and below the position 
of this tooth. A foramen likewise exists before the third premolar \jp 4] of the closed 
row of teeth, corresponding to that more posteriorly situated in the Camel and Lama. 
“ 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 \_p 4] is also like the corre- 
sponding tooth of the latter. The second premolar [jj> 3] is like the first one of the 
Camel, with the exception that it has the antero-internal fold of its crown as well deve- 
loped as the posterior fold, which it joins at the base. The first premolar [p 2] is like 
the first one of the series in the Lama, having a trilobate, flattened oval crown. 
in. lines. 
“ Length of upper molar series 4 8 
Length of lower molar series 4 10 
Length of upper true molar series 3 0 
Length of lower true molar series 3 5.” 
(Leidy, 4 Proceedings of the Academy of Natural Sciences of Philadelphia,’ March 
1858, p. 23.) 
The Cameloid fossil from the “ probably pliocene freshwater deposits of the Niobrara 
Valley, Nebraska,” is thus shown to be not only of markedly smaller size than the 
Mexican Palauclienia, but to differ therefrom, as from Auclienia and Camelns, in a more 
important character, viz. the number of contiguous teeth forming the molar series in 
both upper and lower jaws. In this respect the Procamelus offers an interesting link in 
the transition from the cameline to the true Puminantia, and an additional illustration 
of an approach to a more generalized type of dentition in a species existing at a tertiary 
period anterior in time to that in which the remains of Palauclienia were found. The 
dentition of Palauclienia , in the number of the molar series shown in the fossil from the 
Mexican post-tertiaries, exemplifies an intermediate step between the dentition of Pro- 
camelus , Leidy, and that of the existing Auchenia , Illig. 
The second cameline subgenus indicated by the accomplished and assiduous American 
palaeontologist is the “ Camelops kansanus , Leidy” (Proc. Acad. Nat. Sc. Philadelphia, 
