in the Museum of Buenos Ayres. 87 
figure and those of the periphery is little or nothing: all the 
hexagons of this central part of the shell are of equal size. 
Also the tubercles of the edge of the shell are smaller and 
different in shape; these tubercles have, in G. ciavipes, a low 
conical elevation on the external surface, which is wanting in 
G. spinicaudus. In this species are seen about sixteen tubercles 
at the posterior edge of the shell over the tail, and about twelve 
on the anterior edge over the head. The lateral tubercles are 
almost wholly wanting, and for this reason I do not know its 
exact shape; only, upon the shoulders, these large conical tu- 
bercles may be seen to be a little curved above, and are of the 
same sort as those of which we have before spoken. 
The head bore also on its superior part a shell of plates much 
smaller and irregular, but of the same construction as those of 
the shell. It is not in my power to describe it in detail, in 
consequence of that which we have in the Museum being broken. 
The* same applies to the feet—without doubt well armed with 
plates like those of the living Armadillo, and having at the end 
of the toes large claws, of which there are four long ones on the 
anterior and five wide ones on the posterior extremities. There 
are a great quantity of small plates, very diverse in form and 
size, preserved in the Museum, which show by their construc- 
tion that they were derived from the same skin. These plates 
probably belong to the feet and to some of the small joints, 
where the existing Armadillos have equally small plates, of 
partly formed shell. 
The second species from the Buenos Ayres soil is G. clavipes, 
of which there exist in the Museum an imperfect shell and two 
tails. Undoubtedly it is larger than the first, although, as it is 
broken, we are not exactly aware of its dimensions; but the 
larger size of this animal is not alone demonstrated by the greater 
size of the loose plates of the shell, -but by that of the bones of 
the skeleton which we have in the Museum. At the same time, 
it appears to me much more narrow and elongated than G. spi- 
nicaudus. The specific difference is very clear in the side plates 
of the shell,—the central hexagon being larger than the peri- 
pheral hexagons, and the structure of the surface being finer, less 
elevated, and less rough. The tubercles of the edge of the shell 
appear less convex, and the centre of the external superficies is 
a little elevated, as we have said above, compared with the tu- 
bercles of G. spinicaudus. 
- But the most distinguishable character of this species is the 
existence of a peculiar semicircular border below the tubercles 
of the edge, covered with rhomboid figures. This border does 
not exist in Glyptodon spinicaudus. The tail is very different, 
being long, thin, almost cylindrical, with some rings at its base 
* 
