Mr, Owen on the Glyptodon clavipes. 93 



under and outer side of the bone there is a very small facet, which touches the 

 cuboides. The external cuneiform bone of the Megathere differs from that of the 

 Glyptodon in being thicker as well as broader at its upper part ; but, upon the 

 whole, the external cuneiform bone of the Glyptodon resembles that of the Mega- 

 there more than it does that of the Armadillos. 



The OS cuboides of the Glyptodon* deviates still more than the scaphoid bone 

 from its analogue in the Armadillos in its remarkable antero-posterior compression: 

 it presents an irregular oblong figure, thicker at its inner than its outer margin ; 

 the posterior surface presents a small convex articular surface for that of the os 

 calcis, like which, the curve of the lower part is slightly angular ; this surface is 

 near the upper and outer margin of the bone ; on the inner margin there is a long, 

 narrow, sub-elliptic facet for the scaphoid. The inferior surface of the cuboid 

 (PL XI. fig. 6) is divided by a deep and wide groove for the tendon of the peroneus 

 muscle ; above which is the triangular surface for the metatarsals of the two outer 

 toes, which is bounded above by a rather sharp edge. The posterior part of the 

 lower surface of the cuboid, like the adjoining part of the calcaneum, is smoothed 

 down by the playing of the strong flexor tendons of the toes. 



The middle and inner cuneiform bones are wanting ; but it is evident from the 

 space intervening between the second metatarsal bone and scaphoid, that they must 

 have resembled the external cuneiform in their antero-posterior compressed shape. 



The metatarsals of the three middle and largest toesf are fortunately preserved and 

 entire ; and here we have the most striking deviation from the existing Armadillos, 

 in the extreme shortness of these bones, in none of which does the longitudinal or 

 antero-posterior diameter equal either the transverse or vertical diameters. 



The second metatarsal presents somewhat of a wedge-shape, broadest at its 

 lower and inner sides, and narrowest at its upper and outer sides ; posteriorly it 

 presents a flat surface for articulating with the middle cuneiform bone, which arti- 

 culation is two inches in vertical extent and an inch and a quarter across the upper 

 part, and proves the middle cuneiform bone to have been much smaller than the 

 external one above-described ; this articular surface of the second metatarsal is con- 

 tinuous at its upper and outer angle with a small triangular facet, which articulates 

 with the external cuneiform bone ; a third oblong articular surface is continued from 

 the preceding upon the greater part of a depression on the outer surface of the bone, 

 and this articular surface is applied against a corresponding one on the upper and 

 back part of the middle metatarsal. The articular surface on the anterior part of 

 the bone for the first phalanx of the second toe is slightly convex, longer in the 

 vertical than the transverse directions. At the under part of the bone are two 

 trochlear surfaces for two sesamoid bones. 



* PL X. fig. 3, cb. t Jbid, m, m, m. 



