
THE 
AMERICAN NATURALIST 
VoL. XAV., AUGUST, 1861. 296. 


THE: LITOPTERSA. 
BY E. D. COPE. 
T BERE has been known for many years a mammal of the 
Pampean formation of Buenos Ayres-called by Professor 
Owen Macrauchenia.' It is distinguished by many peculiarities, 
but at the time of its first description its characters were chiefly 
known from the skull and cervical vertebre. The former 
resembles very much that of a horse, but has the strange 
peculiarity of having the external nostrils posterior to their usual 
position in land mammals,—that is, between the eyes, where it is 
placed in the sea-cows or manatees. The teeth were generally 
found much worn, but their general appearance was like those of 
primitive three-toed horses ; but the canines were small and like the 
premolars. The cervical vertebrz, on the other hand, displayed 
characters like those found in the camels, especially in the 
absence of an especial canal for the vertebral artery, which pre- 
sumably ran in the canal of the spinal cord. The position of 
this animal was absolutely uncertain, on account of the absence 
of specimens of the feet; but Professor Owen was inclined to 
place it in the Perissodactyla, and other authorities have followed 
him (Plate XVII.). 
Professor Burmeister, of Buenos Ayres, later obtained still better 
specimens, which included parts of the hind feet. He found that it 
had three toes on both feet, and he published a restoration of it. He 
- | Zool. of the Voyage of the “ Beagle,” Fossil Mammalia, p. 35, Pl. V. and XV.,1389. 
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