Page:Popular Science Monthly Volume 13.djvu/153

Rh fall in its way, as well as to convey other food to the mouth with more readiness. The elongated, protrusible tongue of recent species, as well as of the remaining representatives of the order, gives a clew to the nature of the tongue of the extinct giant armadillos, which was probably used as a herbage-grasping organ, as in the giraffe, and as Prof. Owen finds reason to believe must have been the case with the great extinct sloths, Megatherium, and its allies. It is highly probable, nay, almost certain, that the prehensile powers of the tongues of the Edentata are intimately associated with their want of incisors, or cutting teeth. Similar disappearance or loss of function of the incisors by ruminants, proboscidians, and rhinoceroses, is similarly correlated with a grasping tongue, trunk, or lips.

In living armadillos the grinding-teeth vary in number from twenty-six to thirty-eight, and are in the form of cylindrical or oval columns. All the Hoplophoridæ have thirty-two grinders, sixteen above and the same number below, without enamel, as in recent forms. Two deep grooves run vertically up and down on both the inside and outside of each tooth, causing the appearance of two deep bays on each side in transverse section, Which is not quite twice as long as wide. Unlike living allied forms, these giants had strong descending processes directed downward from the zygomatic arches (cheekbones), similar to those of the great extinct and small modern sloths; and, like the first of the last mentioned, the bones of the pelvis, hind-limbs, and tail, were relatively more massive than in their existing representatives, showing in these features strong resemblances to the sloth-like division of the order. From the deep implantation of the grinding-teeth in the giant armadillos, one cannot resist the inference that, like the great sloths, they were herbivorous. This idea is further countenanced by their size, which, in terrestrial mammals, is usually an accompaniment of herbivorous habits. The features, however, which unmistakably ally them to living armadillos, are the presence of a third trochanter on the femur, and the union of the tibia and fibula and the annular and tubular armor covering the tail. The animal of our figure has the basal part of the tail surrounded and covered with eight slightly mobile rings of armor plates; each one of these rings is supported on the inside by five strong processes of bone which arise radially or like the spokes of a wheel from each of the first seven caudal vertebræ. The first caudal vertebra supports two of the armor-rings. The last fourteen joints of the tail are inclosed by rigid armor, much the same as the end of the finger is covered by a thimble. These terminal joints, confined within this inflexible bony case, become united into a continuous bony rod. Other species have been described which have the tail covered throughout with rings of armor-plates, within which each joint of the tail is separate, as usual in the tails of other vertebrates. In one living species the tail is almost