86 Mr. Owen on the Glyptodon clavipes. 



liar alveoli, occurred to me ; and on comparing the tooth of the Glyptodon with 

 that fragment, I have found that the largest socket in it agrees in size and form 

 with the tooth, and that the longitudinal ridges, which characterize the socket 

 and distinguish it from those of the existing Armadillos, precisely correspond with 

 the peculiar flutings in the tooth itself. 



Thus, then, the suspicion that the bones, discovered with the tesselated osseous 

 coat of mail at Villanueva, might appertain to the same species as the more perfect 

 skeleton and cuirass found near Rio Matanza, is converted into a certainty ; and we 

 may entertain hopes, that the materials will shortly arrive from which we may ob- 

 tain as complete a knowledge of the osteology of the Glyptodon, — the true possessor 

 of the hitherto-described tesselated armour, — as exists of the Megatherium itself. 



The Glyptodon differs from the Megatherium not only in the form and structure, 

 but in the number of its teeth, which appear, from the figure and account trans- 

 mitted to Sir Woodbine Parish, to be eight on each side of each jaw, as in the 

 section of Armadillos called Cabassous by Cuvier. Judging from the same sketch, 

 the Glyptodon differs from all known Armadillos in the form of the lower jaw, 

 and in the presence of a long process descending from the zygoma, in both which 

 respects it resembles, and evidently indicates a transition to, the Megatherium. 

 The same figure shows the tail to be more remarkable for its thickness than its 

 length, and to be protected by armour covering only the upper surface like a roof, 

 and not encompassing it like the verticillate caudal armour of the Armadillos, in 

 both which respects we cannot fail to perceive a correspondence between the 

 Glyptodon and the great Dasypus with armour, described as a Megatherium by the 

 Cure Larranaga. 



I shall refrain, however, from any further remarks or speculations which might 

 be suggested by the figure and notice of the entire Glyptodon, published by Sir 

 Woodbine Parish, and proceed to describe the portions of that animal which have 

 actually reached this country. 



The molar tooth (PI. X. fig. 1 and 2) from the Rio Matanza is fractured, but the 

 grinding surface, and upwards of an inch of the crown, are quite perfect. The whole 

 length of this fragment is two inches and three lines, and there is no indication of a 

 diminution in any of its diameters, from the grinding surface to the opposite frac- 

 tured end : in this respect it agrees with the form of the sockets in the fragment of 

 the jaw of the individual previously discovered, as these sockets terminate abruptly 

 without any contraction : from their depth we may conclude that the length of the 



and armour of the Glyptodon, under the name of Hoplophorus, by M. Lund, in the caverns of the valley 

 of the Rio das Velhas, Brazil, has been announced in a letter from that gentleman to M. Victor Audouin, 

 published in the Comptes Rendus, Avril 15, 1839. Prof. D' Alton has subsequently brought the subject 

 of the Glyptodon before the meeting of the German Naturalists at Erlangen, September 1839, and has 

 proposed for it the generic name of Pachypus. 



