PROFESSOR OWEN ON THE MEGATHERIUM. 
With regard to the fossils from South America, unequivocally referable to the 
Armadillo family, I had myself pointed out the generic distinction of that large 
quadruped, some bones of which had been transmitted along with the gigantic der- 
mal armour by Sir Woodbine Parish, and proposed for it the name of ‘ Glyptodon ’ 
in Sir Woodbine Parish’s work on Buenos Ayres *; and afterwards, stimulated by 
the general tendency of anatomists and palaeontologists to regard the Megatherium 
as being, likewise, a gigantic Armadillo, I entered upon a critical review of all the 
facts of the case which at that time had been obtained, and communicated the result 
in a memoir to the Geological Society, read March 23, 1839 -f-. The general con- 
clusions from this memoir were: — 
1. The opinions of Cuvier and Weiss, in favour of the Megatherium being so 
armed, rest on no better ground than the mere fact of bony armour of some gigantic 
quadruped and the skeleton of the Megatherium having been discovered in the same 
continent. 
2. The skeleton, or its parts, which have been actually associated with the bony 
armour above mentioned, belongs to a quadruped distinct from and less than the 
Megatherium. 
3. No part of the skeleton of the Megatherium presents those modifications which 
are related to the support of a dermal covering. 
4. The proportions of the component tesserae of the bony armour in question to 
the skeleton of the Glyptodon are the same as those between the dermal tesserae and 
skeleton of existing Armadillos, but are much smaller as compared with the bones of 
the Megatherium. 
5. No bony armour composed of tesserae having the same relative size to the bones 
of the Megatherium as in the Glyptodon and existing Armadillos, has yet been dis- 
covered. 
In 1837 I had been put in possession of an additional test of the affinities of the 
Megatherium, by portions of teeth, obtained by Mr. Charles Darwin at Punta Alta 
in Northern Patagonia, from which specimens I was kindly permitted to take the 
requisite sections for microscopical examination. Previous researches by Professor 
Retzius and myself into the structure of the teeth of the Mammalia generally, had 
made me acquainted with the marked difference between the teeth of the Armadillos 
and those of the Sloths in internal structure, and I now found that the Megatherium 
presented the same remarkable compound structure of the teeth as in the Sloths, but 
with additional complexity, by which they still further departed from the compara- 
tively simple structure of the teeth of the Armadillos : the examination at the same 
time proved that there was no true enamel in the teeth of the Megatherium 
* P. 178 6, frontispiece, 8vo, 1838. 
t “ On the Glyptodon clavipes,” Transactions of the Geological Society, second series, vol. vi, p. 98. 
f Zoology of the Voyage of Her Majesty’s Ship ‘Beagle,’ Fossil Mammalia, 4to, 1838-40, p. 103, 
Pis. 31 and 32. fig. 1. 
