346 A MANUAL OF DENTAL ANATOMY. 



teeth may be found in a fresh specimen, but it must not 

 be from too aged an animal, as they become eventually eaten 

 away by a process of absorption. 



These abortive teeth are excellent examples of rudi- 

 mentary teeth, as not only are they stunted, and even 

 ultimately removed by absorption, but they are actually 

 covered in by a dense horny plate which clothes this part 

 of the jaw, and so are absolutely functionless ( J ). 



These horny plates, in their structure analogous to whale- 

 bone, are possessed also by the Manatee and Khytina ; on 

 the free surface they are beset with stiff bristles, and are 

 throughout built up of hair-like bodies welded together by 

 epithelium. 



Behind the region covered in by the horny plates, the 

 Dugong has five molar teeth on each side, of simple form, 

 like those of the Edentata, and consisting of dentine and 

 cementum only. 



By the time the last molar is ready to come into place, 

 the first of the series is being removed by absorption of its 

 root and of its socket. In aged specimens only two molars 

 remain on each side of the jaws. 



The Dugong is also peculiar as having a single deciduous 

 tooth : namely, a predecessor to the incisive tusks ; but it 

 has been doubted whether it be not rather a rudimentary 

 incisor than a milk tooth. 



The molar teeth of the Manatee are much more nume- 

 rous and more complex in form, and they approach to the 

 configuration of the teeth of the Tapir very closely. 



The Manatee has as many as forty-four molars, which 

 are not, however, all in place at one time, the anterior ones 

 being shed before the posterior are come into place ; no 



(*) Similar rudimentary teeth are found in the corresponding deflected 

 part of the jaw of the young Manatee, to the number of twelve. (Gervais, 

 "Histoire Nat. des Mammiferes," vol. ii., p. 312.) 



