383 



end of the tail, and with great regularity, where they form the two lateral series, 

 which terminate by a pair of large, sub-elliptic, thick, hollow ossicles, which in~ 

 close the end of the tail like a bivalve shell, defending this part when dragged 

 along the earth, and even enabling it to pierce the soil like an implement sheathed 

 with iron (Plate II. fig. 7 ■)• The arrangement of the ossicles in the interspaces 

 of the two terminal lateral plates is shown in Plate II. figs. 5 and 6. The number 

 of the lateral plates on each side of the considerable portion of the tail preserved 

 is nine ; from the first of these to the fourth the number of intermediate prin- 

 cipal ossicles below each pair of lateral plates is six of nearly equal size ; beyond 

 this thev decrease to four and three in number. At the superior interspace of 

 the two lateral series there are six sub-equal principal ossicles between each pair 

 of lateral plates as far as the fourth ; they then decrease to five and four in num- 

 ber, those at the centre being of smallest size. 



The circumference of the base of the tail is fourteen inches, that of the apex 

 at the interspace of the penultimate and last lateral plates ten inches. The 

 length of the last lateral plate is three inches and a half, its breadth is three 

 inches. 



PLATE II. 



Upper and terminal views of the carapace of the Glyptodon clavipes. 



Fig. 1 . The upper view of the carapace. 



Fig. 2. The front view, showing the anterior outlet. 



Fig. 3. The back view, showing the posterior outlet. 



Fig. 4. An anterior caudal vertebra, with part of the anterior border of the 

 verticillate bony dermal covering or sheath of the tail. This covering 

 was attached to the vertebra by a close syndesmosis connecting the ex- 

 tremities of the processes which radiated, like the spokes of a wheel, 

 from the centrum or body : the muscular and ligamentous tissues, which 

 occupied the interspaces (g) now filled by the matrix or soil-formation 

 in which the fossil was imbedded, would also form a medium of attach- 

 ment between the endo- and exo-skeletons of the tail. The length of 

 the body of this vertebra is two inches and a half; the diameter of the 

 articular surface of the body is one inch and a half. 



