118 The American Naturalist. [February, 
THE ANCYLOPODA, CHALICOTHERIUM AND 
ARTIONYX.' 
By Henry FAIRFIELD OSBORN. 
Chalicotherium was the most unique mammal of the Mio- 
cene period. So far as known at present, it combined cheek 
teeth of a distinctively ungulate type, ankle and wrist joints 
resembling those of the Perissodactyla, with highly modified 
phalanges, terminating in large cleft ungues which were 
undoubtedly covered with strong pointed claws. It was 
widely distributed over Europe, Asia and North America from 
the oligocene Phosphorites of France (C. modicum) to the early 
Pliocene of the Siwalik Hills (C. sivalense). 
The recent discoveries of Filhol and Depéret in France 
have fully revealed the structure of the skull and limbs, but 
with the exception of the axis, little or nothing is known of 
either the vertebree or scapular and pelvic arches. As we 
learn from these authors the Chalicotherium magnum of Sansan 
(Middle Miocene) was an animal taller than the grizzly bear. 
The head was about nineteen inches long and raised five feet 
above the ground. The limbs were rather slender, and a strik- 
ing peculiarity of this species is that the fore limb is nearly 
twice as long as the hind limb (as indicated by the proportions 
of the radius and tibia). This was not the case in its upper 
Miocene ally (Ancyllotheriwm pentelici) from Pikermi, in which 
the limbs were heavy and of the same length. There were 
three toes upon each foot, but in both manus and pes, the 
fourth or outer digit was the largest instead of the third or 
middle digit as in the Perissodactyla. M. Filhol has repre- 
sented C. magnum as fully plantigrade, but this appears to mẹ 
an error; the perissodactyl displacement of the carpals and 
1 Under the title “ The acne of Chalicotherium,” this article was written some 
months ago. While it was in press, Artionyx, a new type of the order was dis- 
covered, and at the saio suggestion, the article was held back to include a descrip- 
tion of it. o 
