TILELODON? I 44t 
a Capybara, and of much the same general appearance. 1ts skeleton 
is completely known, and shows a singular combination of charactors, 
resembling Jeraden ora generalised Uneulate ou the one hand, and 
the Rodents, especially the Lerceitoay en the other la the presence 
of clavicles it ditfers from all known Uneulates, and in having two 
pairs of lower incisors from all Rodents. The teeth ave ioe Spy. 
meow. 
Peom the Tortiaries of various parts of South Amerion a number 
ot forms move ov less closely allied to Tevedan and Cypotheriiani have 
booew recently dosertbed. but as many of them are very impertectly 
known, and there is much doubt as to their generic position, it will 
bo unnecessary to refer to them further. 
It will thus be seen that, although our knowledge of many of 
these forms is still very limited, we may trace among them a eurious 
chain of attinines, which would seem to unite the Ungulates on the 
one hand with the Rodents on the other: bur further materials 
ave voqiured botore we ean establish with certainty so important a 
relationship, ene which, if true, would alter materially some of the 
prevailing views npon the elassitiention of mammals. 
Group TULODEN TIA. 
Here may be noticed a remarkable group of animals, eatled by 
Marsh, Tillodontia, the remains of which are found abundantly in 
Pra it- Shall ot Pilotheriwam Adiew.  }atualsss. Prem Moos): 
the Lower and Middle Rocene beds of Nerth Amertea. They seem 
to combine the characters of the Ungulata Rodentia, and Carnivora. 
In the genus Cideticrium of Marsh (probably identical with the pre- 
viously deseribed oii diccadus of Leidy) the skull (Pig. 198) resembled 
that of the Bears but the molar teeth were of the Cngnlate type, 
while the large incisers were very similar to these of the Rodents. 
The dental formula is i Soe hp doe S$. The tess pur of incisors 
a 
