xi DISTRIBUTION OF MANATEE 



335 



Manatee l differs from the blubber of the Whale ID that there 

 is no free oil anywhere. 2 



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 AA r hales ; 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 Halitherium recalls the pelvis 

 of the Korqual. 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 

 small bones on each side. 



The Manatees (Manatus} 3 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 



1 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. viif. 1872, p. 127. 



3 Hartlaub, " Beitrage zur Kenntnis der Manatus- Arten," Zool. Jahrb. 1886, p. 1. 



