EXTINCT XENARTHRA.--There are a good many extinct forms of Armadillo, apart of course from the Glyptodons. _Peltephilus_ is referred to later (p. 186). _Dasypus_ was represented by a large form, 6 feet long, with a skull of one foot in length. The genus _Eutatus_ was also large. The carapace was formed of thirty-three distinct bands, of which the last twelve are soldered together, but not fused into a shield as in _Dasypus_, etc. An extinct group of American Edentates, termed the GRAVIGRADA,[113] are somewhat intermediate between the Sloths and the Anteaters. A number of the genera are well known from complete skeletons. One of the typical forms of this group is _Mylodon_, which, together with its immediate allies, is often placed in a separate family, MYLODONTIDAE. _Mylodon_ itself was a large creature, as big as a Rhinoceros. It was covered externally by armour in the skin, which did not form a massive armature as in the Glyptodonts, but was in the {180} form of scattered plates, small and not fused together. The general aspect of the skull is decidedly Sloth-like. As in that animal, the malar bone is bifid posteriorly, and between the bifurcation is embraced the process of the squamosal. This latter is thus more developed than in the Sloth, but there is no actual union between it and the malar. The premaxilla is small. The lower jaw has both coronoid and ascending processes, and is massive. There are five teeth on each side above, and four on each side below, as in the Sloths. There are the normal seven cervical vertebrae and sixteen dorsals. The limbs are not long and slender,but short and strong, the animal having been terrestrial. The fore-feet were five-toed, of which the three inner toes had claws. The hind-feet were only four-toed, and the two inner only were clawed. [Illustration] FIG. 105.--_Mylodon robustus._ (Restoration, after Owen.) _Scelidotherium_ is a genus which is a trifle smaller than the last. It has only four properly-developed toes in the fore-foot, the thumb being rudimentary; of these, the first two bear claws. The hind-feet are also four-toed. Like _Mylodon_, _Scelidotherium_ is a Pleistocene genus. _Glossotherium_ has a skull very much like the last two genera; but it is remarkable for the fact that the nostrils instead of being unprotected with bone anteriorly are there closed by a plate of bone formed by the well-developed premaxillae, the nostrils appearing at the sides, and giving the skull a curious likeness to that of a Chelonian. From a series of recent and most important observations it appears to be clear that this genus has survived into quite modern times.[114] {181}