THE EDENTATA LORICATA. 291 



form, and articulates with the fifth metacarpal, when that 

 bone is present. The ungual phalanges of the manus are 

 long and pointed. The femur has a third trochanter, and 

 the four inner metatarsals are much longer than they are 

 broad. 



The division of the Glyptodontidm contains the single 

 genus Glyptodon^ which is essentially a large armadillo ; but 

 it departs, in some respects, not only from all these animals, 

 but from all other Mammalia^ and even stands alone among 

 the Vertebrata, 



The carapace covers the whole body, but presents no 

 movable thoraco-abdominal zones, inasmuch as it consists of 

 polygonal plates firmly united together, and fringed by a mar- 

 gin of scutes with raised conical surfaces. 



The nasal bones are short and broad, and their free ends 

 do not project so far as the premaxillas ; whence the anterior 

 nasal aperture looks slightly upward as well as forward. The 

 premaxillae, however, are very small bones, and, if they unite 

 with the nasals at all, do so for a very short distance. The an- 

 terior portion of the jugal arch gives off a great downward pro- 

 cess. The mandibular symphysis is very long, and the posterior 

 alveoli of the mandible are situated upon the inner face of the 

 very high perpendicular part of the ramus. The teeth are 

 trilobed, two deep grooves excavating their inner and their 

 outer surfaces. And, as the crowns of those of each jaw arc 

 placed opposite each other, they are worn flat. 



The last cervical and the anterior dorsal vertebrae are 

 anchylosed together into a single " tri-vertebral " bone which 

 moves by a hinge-joint upon the third dorsal. This and the 

 succeeding dorso-lumbar vertebrae are immovably united, and, 

 for the most part, anchylosed, together. The head of the first 

 rib is engaged in the socket furnished to it by the tri-vertebral 

 bone in such a manner as to be immovable, and the rib is not 

 flat, but rounded and columnar. 



In the carpus, the cuneiform bone articulates with the 

 fourth, as well as with the fifth metacarpal, the latter bone 

 being entirely supported by the cuneiform. The metacarpals 

 and phalanges are all very short and broad. The pollex is 

 rudimentary, while the fifth digit is fully developed. 



The supra-condyloid ridge of the femur is not distinct from 

 the third trochanter, even if the latter can be said to exist at 

 all. The metatarsal bones are as broad as they are long, or 

 broader ; and, as in the fore-foot, the majority of the phalanges 

 are comparatively short and truncated. 



