PEOEESSOE HUXLEY ON THE OSTEOLOG-Y OF THE GENUS GLYPTODON. 41 
of the College of Surgeons — a circumstance which justifies the belief that they all 
belonged to one and the same animal, and gives them a peculiar value, the more 
especially as there can be little doubt of the specific identity of the new specimen 
with the animal to which the skull ascribed by Professor Owen to Glyptodon clavipes 
belongs. 
I have thus been enabled to add to what was already known of Glyptodon clavipes, 
descriptions of the most essential peculiarities of the fore part of the skull, the entire 
palate, the mandible, the greater part of the spinal column, the pelvis, and the com- 
plete fore and hind feet, and to announce the existence, in this animal, of a conforma- 
tion of the spinal column hitherto unknown in the Mammalian, and, indeed, in the 
Vertebrate series — the last cervical and two anterior dorsal vertebrae being anchylosed 
together into a single osseous mass articulated by ginglymi with the rest of the vertebral 
column. As another very remarkable peculiarity of this genus, I have pointed out the 
extraordinary characters of the pelvis, and the fact that the cuneiform bone in the carpus 
articulates with two metacarpal bones, the fourth and fifth, while the unciform does not 
articulate with the fifth at all. 
Since the appearance of my paper in the 6 Proceedings of the Royal Society,’ and in- 
deed not until the months of May and June 1863, M. Serres, apparently unacquainted 
with what had been done in these matters, has redescribed the joint between the second 
and third dorsal vertebrae, though he appears to be still unaware of the existence of the 
4 trivertebral bone.’ In addition, M. Serres makes known the interesting circumstance, 
that the posterior edge of the manubrium of the sternum, anchylosed (as M. Nodot had 
pointed out, though M. Serres does not refer to him) with the first pair of ribs, pre- 
sents two concave articular facets, by which it was united with the rest of the sternum, 
which must have presented two convex surfaces adapted to the foregoing in order to 
allow of a movement of flexion. M. Serres is of opinion that this mechanism is 
intended to allow of the retraction of the head : “II est done vraisemblable qu’au 
moment du danger, peut-etre meme que dans le repos ou le sommeil, le Glyptodon 
flechissait le col pour ramener la tete sous la coupole de la carapace”*. 
In his second communication to the Academy, M. Serres still speaks of the “anchy- 
losis of the first two dorsal vertebrae ” onlyf . 
Professor Burmeister, Director of the Museum at Buenos Ayres, has been good 
enough to communicate to me a letter, addressed by him to the Editor of the 4 Nacion 
Arjentina’ on the 5th July, 1863, commenting upon a lecture upon the Glyptodon 
which I delivered before the President and Council of the Royal College of Surgeons, 
which was published in the Medical Times and Gazette for the 28th of February and 
* “Note sur deux articulations ginglymo'ides nouvelles existant chez le Glyptodon, la premiere entre la 
deuxieme et la troisieme vertebre dorsale, la seconde entre la premiere et la deuxieme piece du sternum. Par 
M. Sebkes” (Comptes Eendus, May 11, 1863). 
t “ Deuxieme Note sur le developpement de 1’ articulation vertebro-stemale du Glyptodon, et les mouvemens 
de flexion et d’ extension de la tete chez cet animal fossile. Par M. Sekbes” (Comptes Eendus, June 1, 1863). 
H 2 
