in the Museum of Buenos Aip'es, 85 



like the Peludo, have large hairs on their shells, these hairs issue 

 from the junction of the plates. The others, which arc termed 

 Praopus, such as the Mulita (P. hybridus), have plates more 

 or less unequal, covered with two classes of horny scutes, one 

 large one in the centre on each side, and six smaller at the 

 junction of the plates. In these, the hairs which issue from the 

 shell do not proceed from the joints, but from the same plate ia 

 the circumference of the central scute. 



The description of the shell of Ghjptudun demonstrates that 

 this antediluvian animal was constructed on the same principle, 

 but that it resembled Praopus more than Dasypus ; nevertheless 

 there is a difference between Ghjptodon and Praopus^ in con- 

 sequence of the absence of the moveable rings in the middle of 

 the shell, wliich the living Armadillos possess in varied number 

 in the different species. 



There is an important difference in the surface of the shell be- 

 tween Ghjptodon tuberculatus and other species, G. tuberculatu* 

 not possessing the large hexagonal figures in the plates common 

 to the other species. In G, tuberculatus the surface of each plute 

 is covered equally with small irregular figures, upon which, 

 without doubt, were placed concomitant horny plates, so that 

 the superficies of the shell exhibits the same appearance. Some 

 small holes amongst the small figures demonstrate also the ex- 

 istence of hairs in the shell, but they are more sparse, although 

 each plate also, in its original formation, appears to have pos- 

 sessed six small apertures on its surface. On the edge of the 

 shell are seen large hemispherical or conical tubercles, externally 

 very rough, and covered with a smooth horny shield of the same 

 form. The size of these tubercles varies according to their 

 position in different parts of the edge, increasing in sire towards 

 the posterior part. On the shoulders chiefiy these tubercles 

 are more conical and sharp than those on the head and sides, 

 where it appears to me there arc some smaller and more conical 

 moveable tubercles, below the edge of the shell and upon the 

 legs. I have many of these tubercles in the Museum, but I am 

 ignorant of their collocation on the body of the animal ; never- 

 theless M. Nodot states that his Schist npleuruin had moveable 

 rings at the side of the shell, which he has not recognized in 

 any Ghjjttodon of the Museum, unless in the above-mentioned 

 smaller tubercles. These, by the form of their basal parts, de- 

 monstrate that they are placed on the same cutis, and are united 

 to other parts of the shell. 



As a general character of the whole shell, it may be observed 

 that the central plates become in time united in an entire piece, 

 whilst those of the side arc separated and united one to the 

 other by joints. This separation of the plates continues until 



