300 Dr. H. Burmeister on Glyptodon and its Aliies. 
is composed of five anchylosed vertebre. It consists only of 
four, namely the second to the fifth; and the sixth is free; but 
the seventh is united with the first and second dorsal vertebra 
to form a large piece, which Professor Huxley has named the 
trivertebrated bone, and M. Serres the ‘os metacervicale.” This 
piece has always the same general construction in the four dif- 
ferent species of which well-preserved examples are now before 
me; but the mesocervical bone is not always composed of four 
vertebrae, but in some cases of five. The sixth vertebra is then 
united with the four preceding ones, in the same way as these 
with each other, and the animal has no free vertebra between the 
meso- and metacervical bones. 
Out of the four specimens of necks which I have seen belong- 
ing to the same number of distinct species of Glyptodon, only 
one is constructed in this way, of five united vertebre ; the other 
three have only four vertebra anchylosed. 
As we have other portions of the skeletons of these same indi- 
viduals with scales of the carapace, I can affirm with certainty 
that these three species with four anchylosed vertebre have a 
short conical tail with large rings of conical tubercles, exactly of 
the form described by me in the species which I have named 
G. spinicaudus. As this is the case, I have decided to abandon 
my first name, as indicating not a specific, but probably a generic 
character, and to supply another name of more specific significa- 
tion. Among the species described by other authors, I find in 
the work of M. Nodot on Glyptodon (which was unknown to me 
when I wrote my observations) that this author has formed 
those with short conical tails of tuberculated rings into his genus 
Schistopleurum; that his first species, S. typus, which is very 
fully described, is the same that I had named in ow: museum 
G. elongatus, on account of the narrow and elongated form of 
the carapace, and especially of the pelvis; that the second spe- 
cies, S. gemmatum, Nod., which has the surface of the carapace 
much smoother, was therefore named by myself G. levis; and 
that the third species, described by me as G. spinicaudus, is un- 
known to Nodot, unless it be his G. subelevatus (p. 94, pl. 11. 
fig. 1). As this species is smaller, and has the carapace of a 
more spherical form and the surface of the scales very rough, I 
now propose to name it G. asper. 
Nodot’s S. tuberculatum is not a Schistopleurum, but a true 
Glyptodon; for I suppose the tip of the tail figured in the ‘ Os- 
téographie,’ pl. 1. fig. 5, and copied by Nodot, pl. 8. figs. 7 &8, 
to belong to this species. We have in the museum here such a 
tail as is figured in the ‘ Ostéographie,’ pl. 1. fig. 4 (copied by 
Nodot, pl. 8. fig. 6), and I am much inclined to affirm that this 
and the other are of the same species, the construction of our 
