DESCRIPTION OF A NEW SPECIMEN OF GLYPTODON 553 
must have been practically fixtures in consequence of this arrange- 
ment of the carapace ; and the only moveable parts of the vertebral 
column must have been the tail (of which unfortunately no portion 
has been found in the present specimen), posteriorly moveable on 
the last coccygeal vertebra,—the trivertebral bone with its two pair of 
ribs, capable of an up-and-down motion on the foremost of the thir- 
teen vertebre,—and then the cervicals, more or less moveable upon 
the anterior part of the trivertebral bone, and upon one another. 
I am not aware of the existence of any mammal in which the ver- 
tebral column presents characters of a similar singularity. 
The mobility of the rib-bearing trivertebral bone, by a hinge-joint 
upon the rest of the vertebral column, is peculiarly anomalous. How- 
ever, if, as appears to have been the case, the heads of the ribs 
attached to this bone were incapable of movement, and the first rib 
was furthermore directly anchylosed with the sternum, respiration 
must have been carried on entirely by the diaphragm, if the anterior 
dorsal vertebree had been immoveable on the posterior ones. The 
hinge-like movement of the trivertebral bone, on the other hand, by 
permitting the ribs and sternum to describe a longitudinal arc alter- 
nately downwards and forwards, and upwards and backwards, would 
allow of a most efficient bellows action of the thorax, similar in 
principle to that effected by the ordinary movements of the ribs. 
The trivertebral bone is about ................. 000 6 inches long 
The thirteen vertebre along their convexity... 29 
The sacrum............04. ee eet eee 354 
If three lumbar vertebrz are wanting allow... 9 i 
80 
Judging by the analogy of the Armadillos with which the Gdyp- 
todon presents such close resemblance, and from the shortness of 
such cervical vertebre of Glyptodon as can be reconstructed, the 
neck did not exceed in length ~yth of the length of the vertebral 
column from the first dorsal to the last coccygeal. That would give 
8 inches for the neck, and would give a grand total for the spinal 
column, exclusive of the tail, of 88 inches, or 7 feet 4 inches. The 
length of the carapace of Glyptodon clavipes in the Museum of the 
Royal College of Surgeons is § feet 7 inches. 
The carpus of Glyptodon is in some respects very like that of 
Dasypus sexcinctus, but it consists of eight bones instead of seven, 
the trapezium and trapezoid being perfectly distinct, instead of form- 
ing a single bone, as in Dasypus. The scaphoid articulates with the 
os magnum, and the cuneiform with a metacarpal, as in Dasypus. 
