225, STRENTA 
hones. Of these the American Manatee may be known as J 
americanus, although it has been described under the names ci 
AL latirestris. and VW. australis. The African Manatee (IL senegalensis) 
ditfers from the American species in the following cranial characters : 
the anterior part of the rostrum is shorter. shallower. and altozether 
smaller; the orbit is smaller; the zvzomatic process is more deep 
and massive; the jugal bone is deeper from above downwards: the 
upper margin of the anterior nares is narrower and with a smooth 
and rounded, instead of a thin and serrated, edze: the upper surface 
oi the irontal is fat. instead of concave; the foramen magnum and 
occipital condyles are narrower from side to side, and the srmphvsis 
of the mandible is smaller and shallower. 
Finally, If inunguiz is a fluviatile species confined to the 
Amazon and Orinoco, which has been but recently fully brouzht 
under the notice of zoolozisis. 
Family Hariconm =. 
Haliesr:.*—In the upper jaw a pair of large, nearly straight, tusk- 
like incisors, directed downwards and iorwards, partially coated 
with enamel. In the male they have persistent pulps, and bevelled 
cutting edges, which project a short distance from the mouth, but 
in the female, though they remain through life in the alveolar 
cavity, they are not exserted, and, the pulp-cavity being filled with 
osteodentine, they soon cease to grow (as in the female Narwhal). 
In the young there is also a second small deciduous incisor on 
each side above. At this aze there are also beneath the horny plate 
which covers the anterior portion of the mandible four pairs of 
slender conical teeth lodged in wide alveolar depressions : these 
become absorbed before the animal reaches maturity. The molars 
are usually 3, sometimes 3, altogether, but not all in place at once. 
as the first falls before the last rises above the eum: they are more 
or less nearly cylindrical in section (except the last, which is com. 
pressed and grooved laterally). without distinction into crown and 
root, increasing in size from before backwards, with persistent pulps 
and noenamel. The summits of the crowns are tuberculated before 
Wearing, afterwards flattened or slizhtly concave. Skull with rostrum 
formed by the union of the premaxille in front of the narial 
aperture, longer than the aperture itself. bending downwards at a 
right angle with the basi-cranial axis, and enclosing the sockets 
of the large incisor tusks. Anterior part of che lower jaw bent 
down in a corresponding manner. Vertebre: C 7, D 1$-19, L and 
C30. Tail broadly notched in the middle line, and with two 
pointed lateral lobes. No nails on the fore limbs. Cxeum sinele. 
+ Titger. Prodromus Sust. Mocnim. et Avinm, p. 120 (1221) 
