_Manatus._[116]—Incisors ²⁄₂, rudimentary, concealed beneath the horny oral plates, and disappearing before maturity. Molars ¹¹⁄₁₁, but rarely more than ⁶⁄₆ 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 cervical vertebræ present the remarkable anomaly of being reduced to six in number, the usual vertebral formula being C 6, D 17, L 2, and C 23-25. Rostrum of the skull, formed by the union of the premaxillæ in front of the anterior narial aperture, shorter than the length of the aperture and scarcely deflected from the basicranial axis; premaxillæ and mandibular symphysis not markedly deflected (Fig. 72). Tail entire, rounded, or shovel-shaped. Rudimentary nails on the fore limbs. Cæcum 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 remarkable order. The name _Manati_ was apparently first applied to this animal by 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 Linnæus 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. [Illustration: FIG. 71.—American Manatee (_Manatus americanus_), from life. _Proc. Zool. Soc._ 1881, p. 457.]