MANATIDA 215 
The existing genera present such well-marked distinguishing 
characters that it is on the whole convenient to place them in 
separate families, although, as in so many similar cases, our know- 
ledge of the extinct forms, imperfect as it is, goes far to bridge over 
the distinction between them. 
Family MANATIDA. 
The characters of this and the two following families may be 
conveniently included under the heading of the single genus by which 
they are respectively represented. 
Manatus.\—Incisors 2, rudimentary, concealed beneath the horny 
oral plates, and disappearing before maturity. Molars 44, but 
rarely more than £ present at one time, the anterior teeth falling 
before the posterior come into use; similar in characters from 
beginning to end of the series ; with square, enamelled crowns, the 
grinding surface raised into tuberculated transverse ridges. The 
upper teeth with two ridges and three roots, the lower teeth with 
an additional (posterior) ridge, or talon, and two roots. The cer- 
vical vertebra present the remarkable anomaly of being reduced to 
six in number, the usual vertebral formula being C6, D 17, L 2, 
and C 23-25. Rostrum of the skull, formed by the union of the 
premaxille in front of the anterior narial aperture, shorter than the 
length of the aperture and scarcely deflected from the basi-cranial 
axis ; premaxillz and mandibular symphysis not markedly deflected 
(Fig. 72). Tail entire, rounded, or shovel-shaped. Rudimentary 
nails on the fore limbs. Czcum bifid. Habitat the shores of, 
and the great rivers which empty themselves into, the Atlantic 
within the tropics. These animals are rather fluviatile than marine, 
ascending large rivers almost to their sources. 
The Manatee may be selected for a somewhat full description, 
as being one of the best known representatives of this very remark- 
able order. 
The name Muanati was apparently first applied to this animal hy 
the early Spanish colonists of the West Indies, in allusion to the 
hand-like use which it frequently makes of its fore limbs ; by English 
writers from the time of Dampier (who gives a good account of its 
habits) downwards it has been generally spelt “Manatee.” It was 
placed by Linneeus in his heterogeneous genus Trichechus, but Storr’s 
name Manatus is now generally accepted for it by zoologists. The 
question of the specific distinction of the African and American 
Manatees will be treated of further on, but it will be chiefly to the 
latter and better known form that the following description applies. 
The size of the Manatee has been much exaggerated, but 
1 Storr, Prodromus Meth. Mamm. p. 41 (1780). 
