144 COPE. [VOE. IEE. 
(of the Jurassic and Triassic) are already highly specialized. 
They probably represent the Monotremata of their time. 
Second. The immediate didelphian ancestors of the mono- 
delphous Mammalia have not yet been certainly discovered. In 
the oldest of the latter (of the Puerco epoch) numerous points 
of approach to the insectivorous Jurassic forms occur, especially 
in consequence of the prevalent trituberculy of the molars in 
both epochs. 
Third. The phylogeny of the clawed group has been traced 
back to a common ordinal form which has been called the 
Bunotheria. We trace the Carnivora back to the creodont sub- 
order of the Bunotheria; the Rodentia to the Tillodont; the 
Edentata possibly to the Tzeniodont, and the Insectivora are 
themselves coextensive with the history of the placental series. 
The Ancylopoda only have undergone the alternation of the 
carpal and tarsal bones, which obtains in the Diplarthrous 
Ungulata. 
Fourth. The phylogeny of the hoofed groups carries us back 
to the order Condylarthra, the hoofed cotemporary of the 
Bunotheria. The even and odd toed hoofed mammals are 
traceable back to the Amblypoda, whose oldest representatives 
are the Pantodonta of the Puerco. The Proboscidia and Hyra- 
coidea come directly from the Condylarthra. Moreover, the 
phalanges of the lemurs are not distinguishable by any impor- 
tant characters from the hoofs of the Hyracoidea and Condy- 
larthra. Not only this, but the structure of the foot in these 
three groups is identical in regard to the mode of articulation 
of the first and second rows of the tarsal and carpal bones. 
fifth. The characters of the feet of the Condylarthra agree 
with those of unguiculate placental Mammalia, and bind the 
two series together; a very slight modification only being 
necessary in the case of the foot of the Pantodonta. The syn- 
thesis of the Ungulate and Unguiculate lines is accomplished 
by exceptions to the characters which define them. Thus the 
hoofs of Pantolambda (Amblypoda), Periptychus (Condylarthra), 
and Mesonyx (Creodonta) do not differ by any marked charac- 
ter. Claws occur in the Hapalidz of the quadrumanous line, 
and the ungues of some Rodentia and Edentata (Glyptodon) are 
absolutely intermediate between the hoofs and. claws. The 
Bunotheria with tritubercular molar teeth are then traceable 
