290 THE ANATOMY OF VEKTEBRATED ANIMALS. 



the ground evenly, and indeed the hind-limbs are usually 

 plantigrade, or nearly so ; but, in the singular genus Toly- 

 peutes^ the fore-foot is supported ujDon the extremities of the 

 long nails. The pollex is always present in the fore-foot, but 

 the fifth digit sometimes becomes rudimentary. There are 

 always five toes in the hind-foot. 



In the genus Euphractes, each premaxilla contains a single 

 tooth, which, consequently, is an incisor. 



Tliis group contains two divisions, the DasypodidGe and 

 the GlyptodontidcB / both are South American, but the former 

 is chiefly composed of living animals, while the latter only 

 contains an extinct genus. 



The Dasypodidce are wdiat are commonly known by the 

 name of A.r]nadillos. In this division the thoraco-abdominal 

 shield, when present, as it is in all the genera except Chla- 

 n%ydop)horus^ consists of, at fewest, three, and, at most, thir- 

 teen, transverse movable zones of scutes. 



In the skull, the ends of the nasal bones project beyond 

 the level of the premaxilla3, so that the nasal aperture looks 

 more or less downward. The premaxillse have a considerable 

 size, and articulate largely wdth the nasals. The anterior part 

 of the jugal arch ofi'ers, at most, a rudimentary downward pro- 

 longation. The mandibular symphysis has but a moderate 

 length, and the posterior alveoli of the mandibles do not ex- 

 tend along the inner face of the ascending portion of the 

 ramus of the jaw. 



The teeth of the upper and lower jaw^s alternate, and 

 hence their grinding surfaces w^ear down into ridges. 



The odontoid vertebra is anchylosed with a greater or 

 smaller number of its successors. The cervical vertebrae 

 which follow these have peculiar accessory articular surfaces ; 

 and the hinder dorsal and the lumbar vertebras are also pro- 

 vided w^ith accessory articular facets and processes. A number 

 of the anterior caudal vertebrae are always anchylosed with one 

 another, and with the true sacrals, to form the long sacrum ; 

 and the transverse processes of some of these caudal vertebrae 

 abut against the inner surfaces of the ischia, and become an- 

 chylosed therewith. 



The first rib is broad and flattened, and the anterior piece 

 of the sternum is expanded. The succeeding vertebral ribs 

 are connected by ossified sternal ribs with the sternum, and 

 these are articulated, not only with the sternum, but with one 

 another. 



In the carpus, the cuneiform bone bends round the unci- 



