DESCRIPTION OF THE PLATES. 



21 



Grinding surface of the lower molars of 

 the same. F. Cuvier. Fig. 10. A longi- 

 tudinal section of the lower molars of the 

 same in situ : the section of the middle 

 or antepenultimate molar has touched the 

 lower end of the outer longitudinal groove, 

 which might be mistaken for the remnant 

 of a central pulp-cavity. Original. Fig. 

 1 1 . Transverse section of a molar of the 

 Orycterope. F. Cuvier. 



PLATE 77. 



A portion of a longitudinal slice of the base 

 of a molar of the Orycteropus, magnified 

 150 linear diameters, a, a. The expan- 

 ded apertures of the pulp- cavities of the 

 component denticles. The dark parts of 

 the continuation of the pulp- cavities indi- 

 cate the dried remains of the vascular 

 pulp there situated. Original. 



PLATE 78. 



A portion of a transverse section of a molar 

 of the Orycteropus, magnified 500 linear 

 diameters. Original. 



PLATE 79. 



A section of the tooth of the Mylodon Dar- 

 winii showing the dentinal cells, and a 

 few vascular canals. Original. 



PLATE 80. 



Fig. 1 . Transverse section of the five mo- 

 lars in situ, of one side of the upper jaw 

 of the Scelidotherium leptocephalum. Fig. 

 2. A similar section of the four molars, 

 lower jaw, of the same, £ths nat. size. 

 Fig. 3. First upper molar. Fig. 4. Its 

 grinding surface. Fig. 5. Transverse 

 section of the four molars of one side of 

 the lower jaw, in situ, of the Mylodon 

 Danvinii : ^ nat. size. Fig. 6. Trans- 

 verse section of a molar of the Megalo- 



nyx laqueatus. (Perhaps another tooth of 

 the M. Jeff'ersonii) . 



PLATE 81. 



Fig. 1 . Side view of the upper and lower 

 jaws and teeth of the three-toed sloth, 

 Brady pus tridactylus. Fig. 2. The same 

 of the Bradypus torquatus. Fig. 3. The 

 same of the two-toed sloth (Cholcepus didac- 

 tylus). Fig. 4. Lower jaw, teeth re- 

 moved from left ramus. Fig. 5. Sepa- 

 rate teeth of the same sloth ; e, canine ; 

 b, first ; c, second ; d, third ; e, fourth 

 upper molars. De Blainville.* 



PLATE 82. 



Fig. 1. Longitudinal section of the molar 

 of Bradypus tridactylus, magn. 250 linear 

 diameters. Fig. 2. A small portion of the 

 same, magnified 500 linear diameters. 

 Original, 



PLATE 83. 



A section of the upper jaw and five molar 

 teeth of the Megatherium Cuvieri ; a, ce- 

 ment ; b, vaso-dentine ; c, pulp-cavity ; 

 d, vacuity at the base which was occupied 

 by the thick capsule , less than \ nat. 

 size. Original. 



PLATE 84. 



Section of part of the molar of the Mega- 

 therium, including the hard dentine c; 

 a a', vaso-dentine ; b, cement ; b l , loops of 

 the vascular canals next the dentine. 

 Magnified 500 linear diameters. Origi- 

 nal. 



PLATE 85. 



Fig. 1 . — Teeth of the great existing Arma- 

 dillo (Priodon gigas) ; a, side view of upper 

 molars ; b, grinding surface ; c, ditto of 

 lower molars ; d, side view of lower mo- 



* Ostdographie ties Animaux Vertebres, 4to, 183!), el seq. 



