324 [Dec. 18, 



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 6 inches long. 



The thirteen vertebrae along their convexity . . 29 



The sacrum 35^ 



If three lumbar vertebrae are wanting allow 9 



80 



Judging by the analogy of the Armadillos with which the Glyp- 

 todon presents such close resemblance, and from the shortness of 

 such cervical vertebrae of Glyptodon as can be reconstructed, the 

 neck did not exceed in length y^th 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 5 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. 

 But it is not a little remarkable that, whereas in Dasypus it is the 

 fifth metacarpal whose proximal end partially articulates with the 

 cuneiform, in Glyptodon the corresponding bone articulated wholly 

 with the cuneiform, and not with any of the distal row of carpal 

 bones. The metacarpal articular end of that bone is, in fact, divided 

 into two facets an inner, larger, which articulates with part of the 

 proximal end of the fourth metacarpal, and an outer, smaller, which 

 is appropriated by the proximal end of the fifth metacarpal. 



That the cuneiform should articulate with two metacarpal bones, 

 and that the unciform should not articulate with the fifth metacarpal 

 at all, are very remarkable peculiarities of the wrist of Glyptodon. 



The pisiform is a large curved bone, the proximal end of which 

 articulates by a large facet with the ulna, and by a small one with a 

 facet on the palmar aspect of the cuneiform. It closely resembles 

 the same bone in Armadillos. 



The trapezium and trapezoid, taken together, have a form closely 



