Page:Popular Science Monthly Volume 13.djvu/155

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143
GIGANTIC EXTINCT ARMADILLOS.

naked, whence its name, Dasypus gymnurus. The little three-banded species has the upper face of the tail covered with relatively thick plates. In living specimens I have also noticed that the ears, though very thin, were covered with thin and minute (usually polygonal) scales, both inside and out.

Studies of the feet of the Hoplophoridæ show that they can be divided into two well-defined groups: the first, to which the animal represented in the figure belongs, has four claw-bearing toes on the fore-legs, and four hoof-bearing toes on the hind-legs; the second group has four claw-bearing toes on the fore-legs, and five hoof-bearing toes on the hind ones. As the figure shows, and which is fully supported by the osteology, the hinder extremities are proportionally more massive and longer than the fore ones, which fact, together with the enormously expanded pelvic bones, shows that the creature perhaps raised the fore-part of the body into a more or less nearly vertical position with the help of its tail to reach the leaves of plants upon which it fed, as did its huge congeners, the extinct sloths. This view is favored by the flattened condition of the tail-case or armor toward its extremity, perhaps from the pressure to which it was often subjected from below while in the bipedal position. This also explains the use of the belly-shield to have been to afford protection against enemies from below while in such an attitude, as the animal, because so well protected otherwise, was probably less favored in respect to sight and hearing.

The carapace was supported for nearly half its length upon the haunch-bones (ilia and ischia), as well as by the strong, longitudinal, median, bony crest rising from the lumbar and sacral vertebræ, consisting of their united neural or spinous processes. The carapace rested directly on these bones, and was joined to them by suture, as the roughened and expanded surfaces for such juncture clearly show. The

PSM V13 D155 Dorsal tube and carapas of p tuberculatus.jpg
A, transverse section of the "dorsal tube" of Panochthus tuberculatus: a and b, toramina for spinal nerves; v, vertebral centrum. One-sixth natural size. (After Burmeister.)
B, transverse section through a portion of the carapace and middle of one of the vertebræ (dorsal tube) of a salt-water terrapin: c, carapace; b. proximal extremity of ribs; a a, situation of foramina for the exit of spinal nerves; v, vertebral centrum. Central dark spaces in A and B show the forms of the neural or spinal canals in section. (Original.)
C, side-view of a dorsal vertebra of a European tortoise: a indicates the position of lateral foramina a a in B. Other references same as in B. (After Bojanus.)

entire union of the lumbar and sacral vertebræ into a hollow bony bar, and the union of this to the lateral elements of the pelvic arch, together with the union of both by suture with carapace, rendered any lateral