This beast, which is larger than a mastiff, is generally concealed under
deep water. It is shaggy, with a long tail, ending in a point, and is
armed with very strong nails. It lays hold of horses and mules, as they
are swimming across rivers, and drags them to the bottom. Shortly after,
the bowels of the animal, which it has torn to pieces, are seen floating
on the surface of the water. The yguarò generally dwells in deep gulphs
of rivers, but digs large caverns in the higher banks, where it can hide
both itself and its offspring. On the high shores of the Paraguay, we
often heard a tremendous noise in our nightly navigation, and the
sailors and soldiers informed me that it proceeded from those caves,
which were hollowed by the continual dashing of the water, and had at
length begun to gape.