ORYCTEROPUS. 317 



its anterior part to furrows in the lining membrane of the thick lip. 

 The free surface of the dental mass is sculptured by undulating 

 grooves and risings, adapted to corresponding inequalities in the 

 opposite mass. 



Dr. Brandt(l) has shown by later and more minute exami- 

 nation of the problematical teeth of the Rytina, deposited by Steller 

 in the Petersburgh Collection, that their texture is horny, consisting 

 of minute hollow fibres, placed vertically to the plane of the grind- 

 ing surface of the tooth, but of unusual density. Thus the dentition 

 of the Rytina closely resembles that of the Ornithorhynchus in both 

 the texture and implantation of the teeth, which will probably be 

 found to contain a similar or greater proportion of osseous matter. 

 M. F. Cuvier(2) has suggested, that the above described plates may 

 be analogous in position, as in texture, to the horny covering of the 

 opposed surfaces of the deflected portions of the upper and lower 

 jaws in the Dugong. 



CHAPTER HI. 



TEETH OF BRUTA, (EDENTATA, Cuv.) 



ORYCTEROPUS. 



135. — The Orycterope, or Cape Ant-eater, differs from the 

 edentulous Ant-eaters of South America, in having teeth in both 

 jaws(3). These teeth are of a simple form, but peculiar structure; 

 their common number in the mature animal is || = 26 ; they all 

 belong to the molar series. The anterior teeth are very small, and 

 are not unfrequently wanting, or are concealed by the gum, especially 

 the first in the upper jaw : the second tooth of the upper jaw is 

 small, compressed and obtuse ; it opposes a similar one in the 

 lower jaw : the third and fourth molars increase in size, have an 

 elliptical transverse section, and a triturating surface of two facets : 

 the fourth and fifth molars are the largest in the upper jaw, are 

 of equal size, and have a longitudinal depression in their internal 



(1) Mem. de TAcad. Imp : de Petersb. vi. ser. t. ii. p. 103. 



(2) Histoire des Cetaces, 8vo. 1836, p. 736, (3) PI. 76, fig. 89. 



