1884] The Amblypoda, 1119 
known Taxeopoda possess. I refer to the absence of trochlea, a 
character which will yet be discovered in the Taxeopoda, I have 
no doubt. 
“The Taxeopoda approach remarkably near the Bunotheria, 
and the unguiculate and ungulate orders are brought into the 
closest approximation in these representatives. In fact I know of 
nothing to distinguish the Condylarthra from the Mesodonta, but 
the ungulate and unguiculate characters of the two divisions. In 
the Creodonta this distinction is reduced to very small propor- 
tions, since the claws of Mesonyx are almost hoofs. Some of the 
genera of the Periptychidz present resemblances to the Creodonta 
in their dentition also. 
“The facts already adduced throw much light on the genealogy 
of the Ungulate Mammalia. The entire series has not yet been 
discovered, but we can with great probability supply the missing 
links. In 1874 I pointed! out the existence of a yet undiscovered 
type of Ungulata, which was ancestral to the Amblypoda, Pro- 
boscidea, Perissodactyla and Artiodactyla, indicating it by a star 
only in a genealogical table. This form was discovered in 1881, 
seven years later, in the Condylarthra. It was not until later? 
that I assumed that the Diplarthra are descendants of the Ambly- 
poda, although not of either of the known orders, but of a theo- 
retical division with bunodont teeth’ That such a group has 
existed is rendered extremely probable in view of the existence 
of the bunodont Proboscidea and Condylartha. That the Taxeo- 
poda was the ancestor of this hypothetical group, as well as of 
the Proboscidea, is extremely probable. But here again neither 
of the suborders of this group represent exactly the ancestors of 
the known Amblypoda, which have an especially primitive form 
of the astragalus not found in the former. In the absence of an | 
ankle joint the Amblypoda are more primitive than any other 
division of the Ungulata, and their ancestors are not likely to 
e been more specialized than they. It is probable that a third 
Suborder of Taxeopoda has existed which had no trochlea of the 
astragalus, which I call provisionally by the name of Platyarthra. 
“The preceding paragraphs were written in May, 1882. On 
*Homologies and Origin of Teeth, etc., Journal Academy Nat. Science, Philada., 
1874, p. 20. 
* Report U. S. Geol. Survey W. of rooth mer., p. $82, 1877. 
*This hypothetical suborder has been called Amblypoda Hyodonta. 
