LIST OF TEXT ILLUSTRATIONS 
Page 
Fig. I. Skulls of Santa Cruz Typotheria, Xf. A. Protypotherium australe, A.M.N.H. 
B. Inter atherium robustum, A.M.N.H. C. Pachyrukhos moyani. D. Hege- 
totherium mirabile. .......... 4 
Fig. 2. Left hind foot of Protypotherium australe , Xf. A.M.N.H. .... 6 
Fig. 3. A. Protypotherium australe , left fore foot, Xf. A.M.N.H. B. Nesodon irnbri- 
catus, left fore foot, about Xf ....... 7 
Fig. 4. A. Hegetotherium mirabile, right hind foot, Xf. B. Nesodon imbricatus, right 
hind foot, about Xf ......... 8 
Fig. 5. A. Protypotherium sp., unworn M-, xfr. A.M.N.H. B. Nesodon imbricatus, 
M- & -, slightly worn, Xf 8 
Fig. 6. A. Protypotherium sp., unworn M3, Xtu A.M.N.H. B. Nesodon imbricatus, 
two lower molars, Xf. . . . . . . . . . . 9 
Fig. 7. Dendrohyrax arboreus, left pes, dorsum, Xf ...... 12 
Fig. 8. Protypotherium australe, cranial elements, Xy; . . . . . . 21 
Fig. 9. Protypotherium sp., A. Posterior cervicals and anterior dorsals with ribs in 
place, from left side, Xf. B. the same from below, showing the sternum 
and calcified costal cartilages, Xf ........ 25 
Fig. 10. A. Right manus with opposable pollex and separate centrale, Xy. B. Right 
pes with opposable hallux, X'i (after Ameghino). Both have been referred er- 
roneously to Interatherium robustum. ....... 56 
Fig. 11. Interatherium robustum, showing curved fronto-nasal suture, Xy 59 
Fig. 12. Interatherium excavatum, showing lyrate crest, Xf ... . . . 66 
Fig. 13. Hegetotherium mirabile, skull from in front, Xf ...... 67 
Fig. 14. Hegetotherium mirabile, occiput showing sutures between cranial elements, 
Xt- A.M.N.H 71 
Fig. 15. Hegetotherium mirabile, showing variation in fronto-nasal suture, Xf . 72 
Fig. 16. Hegetotherium mirabile, cranial elements, xf:, A.M.N.H. .... 74 
Fig. 17. Nesodon imbricatus, M - much worn, external view, Xy .... 122 
Fig. 18. The same, crown view, Xy ......... 122 
Fig. 19. Nesodon conspurcatus? Skull, left side, Xf. A.M.N.H. .... 142 
Fig. 20. Toxodon burmeisteri: Skull, left side, Xf. La Plata Museum . . . 143 
Fig. 21. Toxodon burmeisteri: Left scapula, outer side, Xf. La Plata Museum . 151 
Fig. 22. Nesodon imbricatus: Left scapula, outer side, Xf. ..... 151 
Fig. 23. Toxodon burmeisteri: Left humerus, dorsum, Xf. La Plata Museum. . . 153 
Fig. 24. Nesodon imbricatus: Left humerus, dorsum, Xf . . . . . 153 
Fig. 25. Toxodon burmeisteri: Left fore-arm bones, dorsum, Xf. La Plata Museum. 155 
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