42 PROFESSOR HUXLEY ON THE OSTEOLOGY OF THE GENUS GLYPTODON. 
7th of March, 1863, and which contains the substance of the statements previously- 
published in the ‘Proceedings’ of this Society. 
Professor Bukmeister affirms that the skeleton of the Glyptodon in the Museum of 
Buenos Ayres is much more perfect than that in the lloyal College of Surgeons ; that 
it has the seven cervical vertebrae complete ; and that the five middle cervical vertebrae 
are anchylosed together, while the seventh is very delicate and fragile. Under these 
circumstances, it would appear that Professor Burmeister considers the trivertebral 
bone (my description of which he confirms) to be composed of the three anterior dorsal 
vertebrae. 
Professor Burmeister is further of opinion that the peculiar mechanism of the joint 
formed by the trivertebral bone with the rest of the spinal column has not that respi- 
ratory function which I have ascribed to it; but, with M. Serres, he thinks that its 
object is to allow of the application of the cephalic shield to the anterior aperture of 
the shield of the body. Professor Burmeister goes on to remark — 
“ As little do I agree with Mr. Huxley as to the immobility of the ribs, which are 
wholly wanting in the London skeleton. The skeleton of the Museum of Buenos 
Ayres has nine ribs, three of which being complete, prove that they possess a certain 
mobility, moving downwards and backwards on their articulations with the spinal column, 
as in other Mammalia, but without doubt in a manner somewhat different from the 
ordinary way.” 
I am at a loss to divine on what grounds Professor Burmeister ascribes to me the 
opinion that the ribs are immoveable, and why he affirms that they are wholly wanting- 
in the London skeleton. What I have stated is, that the first rib is immoveable ; and 
so far from the ribs being wholly wanting, I have particularly mentioned their presence *, 
and have alluded to the characters of the first *f\ 
Professor Burmeister adds that I am in error in supposing that the dorso-lumbar 
vertebrae were immoveably united. I believe, however, from Professor Burmeister’s 
own words, that my description is substantially accurate. These words are : — 
“ There exists a moveable place between the dorsal and the lumbar vertebrae, though 
the mobility is not so complete as that of the three first anchylosed vertebrae upon the 
following ones. In this part, the skeleton of Buenos Ayres presents a complete column, 
formed by eleven vertebrae incorporated into a solid piece, of a very peculiar form, with 
three crests in the upper part, the two lateral of which bear the ribs in articular exca- 
vations. The total number of dorsal vertebrae and of ribs is therefore fourteen. Then 
follow on these the lumbar vertebrae, all anchylosed together and immoveably united 
with the sacrum.” 
I do not venture to doubt the accuracy of Professor Burmeister’s description of the 
specimen under his own eyes ; but nevertheless, as will be seen by-and-by, it is also true 
that the account I have given of the Glyptodon in the College Museum is quite accu- 
rate. And indeed, as Professor Burmeister admits that all the dorsal and all the 
* Proceedings of the Royal Society, Z. c. p. 317. t Ibid. p. 319. 
