92 Mr. Owen on the Glyptodon clavipes. 



flatter, and the posterior surface is produced in the form of a strong ridge below 

 its level. The anterior articular surface for the os cuboides is relatively smaller 

 than in the Armadillos ; it is flat instead of concave, with the lower part bent for- 

 wards at an open angle with the vertical part of the surface : there is a much greater 

 extent of rough surface on the anterior part of the calcaneum, below the cuboidal 

 facet, than exists in the Armadillos ; with these diflierences, however, the os calcis 

 of the Glyptodon presents a much closer correspondence to that of the Armadillos 

 than to that of the Megatherium. 



Scaphoides*. — I have already spoken of the peciiliar aspect of the scaphoidal 

 articular surface in the astragalus of the Glyptodon : the verticality of the articular 

 surfaces upon the scaphoid bone for the cuneiform bones is produced by the great 

 thickening of the lower part of the scaphoid as compared with the upper, which thus 

 compensates for the obliquity of the articular surface on the astragalus. The sca- 

 phoid bone of the Glyptodon presents a remarkably compressed form ; the poste- 

 rior articular surface (PI. XI. fig. I, a) is concave, chiefly in the transverse direc- 

 tion, and corresponds in size and form with the opposed surface on the astragalus ; 

 a rough flattened margin, of about half an inch in breadth, intervenes between the 

 posterior and anterior vertical articular surfaces, at their upper and outer parts. 

 The tibial side of the scaphoid is produced and thickened, and is irregularly rounded ; 

 a very peculiar elongated conical and slightly twisted process {ib. b) is continued 

 from the middle of the inferior thickened margin ; the base of this process is sepa- 

 rated by a smooth notch from the internal protuberance. The articular surface for 

 the external cuneiform bone {ib. fig. 2, c) is the largest of the three and of a semi- 

 lunar figure ; the middle articular surface (ib. d) is in the form of a narrow verti- 

 cal ellipse ; the internal surface {ib. e) looks inwards and forwards, as in the Arma- 

 dillos : external to the cuneiform articular surfaces there is a small narrow vertical 

 facet for a part of the os cuboides. 



Notwithstanding the peculiarities which have been pointed out, the scaphoides 

 of the Glyptodon resembles that of the Armadillos much more than it does that of 

 the Megathere, from which it diflers more especially in the uniform concavity of 

 the posterior articular surface. 



The external cuneiform bone of the Glyptodonf diffiers from that of the different 

 species of Dasypus in its remarkably compressed form ; it is, in fact, a simple trian- 

 gular plate of bone, with the posterior surface smooth and very slightly concave 

 for the articulation with the scaphoid ; the anterior surface very slightly convex 

 for the articulation with the metatarsal of the third toe : the outer contour of the 

 bone is convex, the inner one concave ; the anterior articular surface encroaches 

 a little on this side to join a portion of the metatarsal of the second toe : on the 

 * PI. XL figs. 1 and 2. f PI. X. fig. 3, en. 



