[Illustration: MANATEE.]
These animals are distinguished by the arrangement of their teeth and by
certain peculiarities in the structure of their head. The number of
their teeth is considerable, their grinders have roots distinct from the
crown of the tusk, which forms a grinding surface composed of transverse
elevated ridges. The incisor teeth are quite rudimentary. Their only
limbs somewhat resemble hands, and their fingers are provided with
nails, while the fin at their tail is not forked, but single, and of an
oval shape. These creatures seem to be intermediate in their structure
between the Pachyderms and the Cetaceans, seeing that their grinding
teeth very much resemble those of the Tapirs. Three species are known to
Naturalists—one from South America, one from Senegal and one from
Florida.