Mr. Owen on the Glyptodon clavipes. 105 



This plate is hollow or excavated to its extremity, and presents in its concavity vestiges of caudal ver- 

 tebrae very distant from one another. 



" The exact dimensions of this tail, which is stated to resemble the tusk of an Elephant, are as fol- 

 lows: 



Inches. Lines. 



Length .19 



Circumference at origin 13 6 



Ditto middle 10 11 



Ditto two inches from end 8 4 



Thickness of the bony plate or roof 8 



From the Banda Oriental." 



This notice of the tail of the Glyptodon is very satisfactory, as it confirms the accuracy of the sketch 

 of that discovered in the Rio Matanza, while both correspond with the distinctive character of the 

 armour of the tail pointed out by the Cure Larranaga in the fossil Edental, which he calls both a Dasy- 

 pus and a Megatherium, 



We have thus evidence of the discovery of the remains of five individuals of a 

 large edentate species, undoubtedly covered with armour, and more or less cor- 

 responding with the characters of the genus Glyptodon, which are deduced in the 

 present paper from the structure of both dentary and locomotive organs. 



That the portions of fossil dermal armour now in England, though exhibiting 

 proportions which may be termed gigantic as compared with the osseous carapace 

 of the Armadillos, belong, not to the Megatherium, but to the Glyptodon, cannot 

 admit of doubt. It is always difficult, however, to establish a negative : but 

 that the Megatherium possessed no analogous covering, will be also, I trust, con- 

 ceded by those who may be willing to admit the validity of the arguments adduced 

 at length in the foregoing pages, and which may be briefly summed up as fol- 

 lows : — 



1st. 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 disco- 

 vered in the same continent. 

 2nd. The skeleton, or its parts which have been actually associated with the bony 



armour above mentioned, belongs to a different and smaller quadruped. 

 3rd. No part of the skeleton of the Megatherium presents those modifications 



which are related to the support of a bony dermal covering. 

 4th. 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 tes- 

 serae and skeleton of existing Armadillos, but are vastly smaller as compared 

 with the bones of the Megatherium. 



VOL. VI. — SECOND SERIES. P 



