14 VEKTEBRATA. 



upon the same streams, and, reaching the quiet waters, sank down in their muddy 

 bed. The whole area has since been elevated ; the estuary mud has been con- 

 verted into wide and level plains, and the shores and submarine banks of a former 

 sea now form low headlands along the present coast. It was in this recent forma- 

 tion — referable to the Pleistocene period, because most of its shells are still living 

 in the ocean — that the Megatherium was entombed. Its bones are almost exclu- 

 sively found in the cliffs and steep banks of rivers ; thus far the Rivers Salado 

 and Luxan. The race was not exterminated by some great cataclysm ; for the 

 small bones, like the kneecap, of a cotemporary mammal were discovered by 

 Darwin in the same deposit, all lying in their proper relative position. Like the 

 Aborigines of our own continent, like the Dodo of Mauritius, the Edentate giants 

 perished one after another, in the lapse of infinite ages, by those changes of cir- 

 cumstances in the organic and inorganic world which are always in progress. 



The Megatherium was buried in a hecatomb of extinct monsters. By its side 

 we find the bones of the kindred Mylodon, Megalonyx and Scelidotherium, all of 

 them Sloths ; the Glyptodon and Schistopleurum, the Toxodon and Mastodon, the 

 Machairodus and Macrauchenia. The Megatherium and its associates have been 

 discovered in the Pleistocene deposits of the United States ; but South America 

 was then, as it is now, the metropolis of the Edentates. 



This model consists of 124 different casts, representing more than 175 bones.* 



Price, packed but not painted, $250.00. 



No. 24. Megatherium Cuvieri, Desm. 



Skull and Lower Jaw. Size, 32 x 24, Price, mounted, $15,00. 



No. 25. Megatherium Cuvieri, Desm. 



Lower Jaw. Size, 27x20. Price, $5.00. 



No. 26. Megatherium Cuvieri, Desm. 



Tooth. 

 Size, 7x2. Price, $0.60. 



No. 27. Megatherium Cuvieri, Desm. 



Right Fore-Foot. Size, 16 x 13. Price, $5.00, 



No. 28. Megatherium Cuvieri, Desm. 



Right Hind-Foot. Size, 30 x 10. Price, $6.50. 



No. 29. Megatherium Cuvieri, Desm. 



Right Hind-Foot with Tibia. Size, 30 x 28, Price. $10.00. 



No. 30. Megatherium Cuvieri, Desm. 



Right Hind-Leg with Foot. Size, A% ft. x 2}6 ft. Price, mounted, $25. 



No. 31. Megatherium Cuvieri, Desm. 



Femtjr. Size, 28 x 16. Price, $6.00. 



* For particulars about mounting the Megatherium, sea Appendix A. 



