384 



a, The body of the vertebra. 



b, The neural spine. 



c, The ha?mal spine, restored, in dotted outline from a consecutive vertebra : 



the processes on the centrum indicate the existence and strength of the 

 bony arch for protecting the blood-vessels of the tail. 



d, The upper transverse process continued from the neural arch. 



e, The lower transverse process continued from the centrum. 



f, The free anterior border of the bony covering of the tail ; it is rounded off, 

 and from two to three lines in thickness, but gradually increases to half 

 an inch in thickness opposite the distal end of ihe vertebra ; and the 

 bony covering acquires a thickness of three-fourths of an inch towards 

 the posterior end of the tail. 



Fig. 5. The under surface of the extremity of the tail. 



Fig. 6. The upper surface. 



Fig. 7- The end of the tail. 



PLATE III. 



Views of the cranium of the Glyptodon clavipes. 



Fig. 1. Upper surface of the cranium. 



Fig. 2. Under surface of the cranium. 



These views are reduced one-half the natural size. 



The occipital condyle («) presents a convexity in the vertical direction, which 

 describes more than a semicircle, and is slightly convex transversely, but is 

 narrower in that direction than it is in the Mylodon : it is directed in the 

 Glyptodon backwards and obliquely outwards. The occipital foramen (b) is 

 very large and transversely elliptical ; its plane is inclined from below upwards 

 and backwards 20° beyond the vertical line. The anterior condyloid foramen 

 (c) 5 though large, is relatively smaller than in the Mylodon, and is situated close 

 to the anterior border of the condyle. The depression for the digastric muscle 

 (a) is perforated and separated from the condyle by a wider tract of the par-occi- 

 pital (e) than in the Mylodon, and the petro-mastoid {/), below the digastric 



