546 © The American Naturalist. [June, 
“1st. The tail is represented as flexible, and terminating én a 
somewhat flattened, though, on the whole, solid, pointed paddle, 
whereas it is almost perfectly inflexible, the paddle at the extrem- 
ity being completely flattened and rounded at the vertex. 
“ 2d. The fringe issuing from the ultimate and large ring of the 
dorsal carapace, instead of being drooping, as often depicted, where 
it unites with that of the exterior ring of the truncated extremity, 
forms a double, somewhat bristly fringe, standing out well at right 
angles to that truncated extremity. 
“3d. The lateral edges of the dorsal chitinous shield are sharply 
serrated, instead of forming a continuous wave-line. 
“4th. The eye, instead of being distinctly visible, is rudimentary 
and hidden by the fringe and mantle. 
“sth. The projection of the slightly convex truncated extrem- 
ity is very exactly a section of a circle, the center of which is a 
point whence issues the tail, the whole of this truncated armor 
plate forming a very hard, solid, bone-like structure, which at once 
suggests the use to which it is devoted,—viz., to act as a rammer 
to consolidate the sand and to fill up the entrance to its burrow, 
from the inside, and thus prevent the ingress of its enemies. 
“6th. When walking, the C. truncatus plants both fore and 
hind feet on the soles, and not on the contracted claws, as is the 
case with the ant-eater, carrying its inflexible tail, which it has no 
power to raise, trailing along the ground and inclined downwards 
from the body. As it commences to excavate, the fore feet are 
first employed, and immediately afterwards, supporting its body 
on the tripod formed of these and of the extremity of the tail, both 
hind feet are set to work simultaneously, discharging the sand 
with incredible swiftness. Although analogy and form would 
seem to indicate it, I never could detect the tail aiding in the 
operation of excavation ; in fact, its inflexibility precludes this idea. 
The only use of the flattened extremity appears to me to be to 
furnish it with a more secure point of support in the shifting 
sands. | 
“ Sluggish in all its movements, except as a fodient, in which — 
capacity it perhaps excels all burrowing animals, the C. truncatus 
performs the operation of excavation with such celerity that & 
