1118 The Amblypoda. [November 
of a cusp posterior to its internal extremity in the Dinocent 
presents a further obstacle to such a determination. This cuspis 
probably homologous with the posterior internal tubercle of Man- 
x 
Fic. 11.—Last three temporary molars, and first true molar partly protruded, of 
a Coryphodon from New Mexico, nat. size. Original, from Report U. S. G. G. Sur 
vey W. of 1ooth mer., G. M. Wheeler, Vol. Iv, pt. II. 
teodon (Fig. 9 f), and is, therefore, the posterior internal of the 
quadrituberculate molar type. The internal extremity of the pos 
terior crest of the crown in the Dinocerata cannot, therefore, bè 
that cusp, and that ridge is not a posterior transverse crest, such 
as is present in most Perissodactyla. e 
It is interesting to observe that the fourth superior deciduous 
molar in Coryphodon (Fig. 11) has essentially the same structure 
as the true permanent molar of Pantolambda (Fig. 3). 
The origin of the Amblypoda has not yet been tr i 
was known on this point, as well as on the question of pei 
scendants of the order, was stated as follows in my pipa 
classification of the ungulate Mammalia, published in 1882: 
“ As regards the inner part of the manus, I know of me 
which presents a type of carpus intermediate between that m 
Taxeopoda and Amblypoda on the one hand, and the Pen probe 
tyla and Artiodactyla on the other. Such will, however, wot 
bly be discovered. But the earliest Perissodactyla, as for 13 a 
Hyracotherium, Hyrachyus and Triplopus, possess the ~~ 
the later forms, Rhinoceros and Tapirus. The order ~a while 
occupies an interesting position between the two groups, | of the , 
it has the carpus of the primitive type, it has the ere 
later orders. The bones of the tarsus alternate, th less 
decided advance on the Taxeopoda. This order 1S © i 
primitive than the latter, although in the form of ~ wie of the 
no doubt retains some primitive peculiarities which "a : 
_ ¥Palzontological Bulletin No. 35- Proceedings Amer. Philosoph. panei 
aao 
