DESCRIPTION OF THE PLATES. 



25 



dentinal tube magnified 400 linear times, 

 showing two dichotomous subdivisions, a 

 fewprimary branches, the secondary minute 

 lateral branches, and the terminal cellules 

 at the boundary line next the enamel. 



PLATE 103. 



Fig. 1. — A portion of a section from the 

 extremity of a worn upper tusk of the 

 Mastodon giganteus, magnified 350 dia- 

 meters, showing at d, the dentinal tubes 

 and cells, and at c, the thick cement ; c, 

 a group of the radiated granular cells of 

 the cement. Fig. 2. A portion of a 

 section of a molar of the Wombat (Phas- 

 colomys Vombatus), magnified 350 dia- 

 meters, showing d d, the terminations of 

 the dentinal tubes ; e, the enamel ; and 

 c, c, the coronal cement. Original. 



PLATE 104. 



Fig. 1 . — Right ramus of the lower jaw of a 

 Porcupine (Hystrix cristatus), showing, i, 

 the crown, and v the exposed pulp, re- 

 ceiving its recurrent nerve, of the scalpri- 

 form incisor : p, the premolar ; m, the 

 three true molars. Fig. 2. The upper 

 jaw of the Patagonian Cavy (Dolichotis 

 patachonica) : i, incisor ; p, premolar ; 

 m, molars. Fig. 3. Teeth of lower jaw 

 of the Patagonian Cavy : i, the incisor ; 

 p, the premolar ; m, the true molars. 

 Fig. 4. Upper molars of the Guinea-pig 

 (Cavia porcellus) : d,p, deciduous molar ; 

 p, permanent premolar ; m, molars. 

 Fig. 5. Upper teeth of the Rabbit (Lcpus 

 cuniculus) : i, permanent incisor ; d i 2, 

 deciduous second incisor ; i 2, permanent 

 second incisor ; p d, deciduous molars ; 

 p, premolars ; m, true molars. 



PLATE 105. 



Grinding surface of molar teeth of various 



genera of Rodents. Fig. 1. Molar series, 

 right side, upper jaw, magnified, of the 

 Squirrel (Sciurus vulgaris). F. Cuvier. 

 Fig. 2. Right series, upper jaw, magni- 

 fied, of the Flying Squirrel (Pteromys 

 taguano'ides) . F. Cuvier. Fig. 3. Right 

 series, upper jaw, magnified, of the 

 Souslik, or Pouched. Marmot (Spermophi- 

 lus cilillus) ; a, young ; b, old molars. Cuvier, 

 Oss. Foss. Fig. 4. Right series, upper 

 jaw, magnified, of common Marmot 

 (Arctomys alpinus). Cuvier, Oss. Foss. 

 Fig. 5. Right series, upper jaw, nat. size, 

 of the Beaver (Castor fiber). Cuvier, Oss. 

 Foss. Fig. 6. Right series, lower jaw, 

 magnified, in two stages of attrition of 

 the Dormouse (Myoxus avellanus). F. 

 Cuvier. Fig. 7. Molar series : a, upper; 

 b, lower jaw, magnified, of the Jerboa 

 (Dipus sagitta). F. Cuvier. Fig. 8. 

 Left series, upper jaw, magnified, of the 

 Gerbille (Meriones indicus) . Cuvier, Oss. 

 Foss. Fig. 9. Right series, upper jaw, 

 magnified, unworn, of the Rat (Mus 

 decumanus). Cuvier, Oss. Foss. Fig. 10. 

 Right series, upper jaw, magnified, in 

 two stages of abrasion, of the Rat (Mus 

 decumanus). F. Cuvier. Fig. 11. Right 

 series, upper jaw, in two stages of abra- 

 sion, of the Cape-Mole (Orycteromys 

 capensis). Cuvier, Oss. Foss. Fig. 12. 

 Right series, upper jaw, magnified, of the 

 Field- Vole (Arvicola amphibia). Cuvier, 

 Oss. Foss. Fig, 13. Right series, upper 

 jaw, of the Porcupine (Hystrix cristatus). 

 Cuvier, Oss. Foss. Fig. 14. Right series, 

 upper jaw, magnified, of the Agouti 

 (Dasyprocta Agouti). Cuvier. Oss. Foss. 

 Fig, 15. Right series, upper jaw, of the 

 Cavy (Ccclogenys fusca). Cuvier, Oss. 

 Foss. Fig. 16. Right series, upper jaw, 

 magnified, of the Guinea-Fig (Cavia por- 

 cellus). Cuv. Oss. Foss. Fig. 17. Right 



