Geological Society. 517 



not belong to the Megatherium ; and that the dentition of the extinct 

 species differed more widely from that of the existing subgenera of Ar- 

 madillos than the respective dental characters of the latter differ from 

 each other. As the portions of the skeleton were not sufficient to en- 

 able Mr. Clift to determine satisfactorily the characters of the animal, 

 no account of them was given in his memoir on the Megatherium, but 

 they form the subject of Mr. Owen's paper, of which this is a notice. 

 Soon after the arrival of Sir Woodbine Parish's collection, the Col- 

 lege of Surgeons had casts made of the bones, and presented them to 

 different museums, including the Jardin du Roi, whei-e they were 

 examined by M. Laurillard and Mr. Pentland. These naturalists 

 also concluded, especially from the bones of the foot, that the re- 

 mains were not portions of the Megatherium, but of a gigantic 

 Armadillo. 



More recently, Sir Woodbine Parish received an account of the 

 discovery, in the bank of a rivulet near the Rio Matanza, 20 miles 

 south of the city of Buenos Ayres, of a perfect skeleton and bony 

 covering, and with the description, he also received a fragment of 

 a tooth and a drawing of the animal. On examining the tooth, Mr. 

 Owen found, that it belonged to an animal referable to the Edentata 

 of Cuvier, but indicative of a new sub-genus of the Armadillo family ; 

 and for which he proposed the name of Glyptodon, in reference to 

 the sculptured character of the tooth. Subsequently, he compared 

 the tooth with the alveoli in the fragment of the jaw in Sir Wood- 

 bine Parish's collection ; and he found that the peculiar longitudinal 

 ridges in the sockets precisely corresponded with the flutings in the 

 tooth itself, whereby he was enabled to prove, that the bones dis- 

 covered with the tessellated coat of mail at Villanueva appertained 

 to the same species as the more perfect skeleton and cuirass found 

 near the Rio Matanza. 



Judging from the drawing transmitted to Sir W. Parish, the Glj^- 

 todon differs from the Megatherium not only in the form and struc- 

 ture of the teeth, but in the number, which appears to be eight on 

 each side of each jaw ; and from all known Armadillos in the form 

 of the lower jaw, as well as in the presence of a long process de- 

 scending from the zygoma, in both which respects it resembles the 

 Megatherium. According to the same figure, the tail was protected 

 by a narrow bony covering on the upper surface only, and was not 

 encompassed by it as in the Armadillos. 



Mr. Owen then proceeds to describe the remains of the Glyptodon 

 ■which have arrived in England. The molar tooth is only a fragment, 

 but the grinding surface and upwards of an inch of tlie crown are 

 perfect, the whole length being about two inches. There is no in- 

 dication of a diminution in any of its diameters from the grinding 

 surface to the opposite end, and the alveoli in the fragment of the 

 jaw terminate abruptly without any contraction, 'llic teeth are 

 more compressed than those of the Megatherium, and differ from 

 them in intimate structure, reseml)ling in this respect tlie teeth of 

 the Armadillos. From all known Armadillos, the Glyptodon, how- 

 ever, is distinguished by the tooth having on both the outer and inner 



