XI DISTRIBUTION OF MANATEE 335 
Manatee! differs from the blubber of the Whale in that there 
is no free oil anywhere.” 
The skeleton of the Sirenia is strong and massive, thus con- 
trasting with the loosely-textured bones of the Cetacea. The 
cervical vertebrae are, as a rule, free, but the second and third are 
fused in Manatus and the extinct Halitherium. It is noteworthy 
that in Rhytina the cervical vertebrae have the exceedingly thin 
centra that characterises the neck vertebrae in Whales. The ribs 
are most of them firmly articulated by two heads. The breast- 
bone is generally reduced, as in Whales; and but few ribs are 
attached thereto. The vertebrae, moreover, are well locked to- 
gether by zygapophyses, and not loosely attached as in Whales. 
The shoulder blade is long and narrow, and not unlike that of 
the Seals. It is totally unlike the peculiarly-modified scapula 
of the Whale tribe. But, as in the latter, there are no clavicles. 
The hind-limbs are only represented by the pelvis; and this 
is a rudimentary structure, varying, however, in the degree of its 
degeneration. That of the extinct Halitheriwm recalls the pelvis 
of the Rorqual. There is a single triradiate bone, with an aceta- 
bular cavity for the rudiment of the femur in the centre; it 
suggests that here the three normal elements of the pelvis have 
become fused into a single bone. In the Dugong there are two 
smali bones on each side. 
The Manatees (Manatus)° are found in the fresh-waters and 
along the Atlantic coasts of South America and Africa. It 
appears that there are four species, of which one only is African, 
the others American. Report asserts the former occurrence of 
this genus on the shores of St. Helena. 
The Manatee is provided with only six cervical vertebrae, a 
- fact which distinguishes it from the other existing genera of its 
group. A remarkable feature which it exhibits is the large 
number of molar teeth. These apparently go on increasing in- 
definitely during its life, the suggestion being that they are worn 
away by the nature of the food—algae with much sand intermixed. 
As many as twenty molar teeth have been counted in one half of 
the jaw, and ‘there is no reason to forbid the assumption that they 
' Kiikenthal has discovered a thick coating of rudimentary hairs in the foetus 
of the Manatee, thus showing that it is the descendant of an animal furry like 
a Seal. 
2 ““On the Manatee,” in Trans. Zool. Soc. vol. viii. 1872, p. 127. 
] 
* Hartlaub, ‘‘ Beitriige zur Kenntnis der Manatus-Arten,” Zool. Jahrb. 1886, p. 1. 
