in the Museum of Buenos Ayres. 89 
and size, forming in the beginning of the tube two circles of 
eight small ellipses in each, and at the side three other bands of 
other and larger ellipses; the ellipses of the median band are 
much larger and more extended towards the point of the tail, 
where are to be seen two of a longitudinal diameter of 8 inches. 
But a large part of the tail of the same species in the Museum, 
recently discovered by me on the banks of the river Salado, is 
twice as long, which demonstrates that this animal was capable 
of attaining a truly gigantic size. The distinction between the 
three species is easy, as the foregoing description proves ; but it 
is not easy to know whether the other species already described 
are well founded. Mr. Owen has further accepted two species, 
which he terms G. ornatus and G. reticulatus. Of the first he 
says that it is smaller than G. clavipes—a character which ap- 
pears to indicate its identity with G. spinicaudus ; but, without a 
knowledge of the shape of the tail of G. ornatus, it is not possible 
to know whether the two are really identical or different. Of 
G. reticulatus the author says that it is of the same-size as G. 
clavipes, but different in its structure, which is reticulate on the 
surface of the shell-plates—a character which might apply to 
the plates of G. tuberculatus which are situated in the centre of 
the shell. 
The three species of Hoplophorus, founded by Dr. Lund, I 
only know by the description of some parts which the author 
has given in the work already cited. They show a great simi- 
larity to the Glyptodons of Buenos Ayres ; but, without an exact 
comparison of the objects themselves, it is impossible to know 
whether they are identical or different. 
The accounts which I have read of the work of M. Nodot state 
that the author has established fourteen species, without specify- 
ing their differences; and for this reason we cannot arrive at 
any judgment whether they are well founded or not. It appears 
that we have accepted all the species already enumerated by 
different authors ; but in this case the number of fourteen ap- 
pears to be exaggerated, as can be proved by an examination of 
the three different species from Buenos Ayres. 
Let us now pass to the examination of the skeleton. 
For some time the feet, the tail, and the head of Glyptodon 
have been incompletely known. The same statement applies to 
the vertebral column and to the pelvis, recently described by Mr. 
Huxley, as the skeleton which was in his hands was very defee- 
tive, which has consequently rendered his description very in- 
complete. 
In the Museum of Buenos Ayres there is a nearly complete 
skeleton, known up to the present time by a photographic figure 
made by the able artist Sefor Aldanondo (Calle Florida, 129), 
