30 



VERTEBKATA. 



exhibit the dental inferiority by nniltiplication of the simple 

 molars, which in the Great Armadillo {Dasypus giyas) reaches 

 the number one hundi'ed. Excepting the Sloths, the order is 

 carnivorous. The order is limited in number of species, and 

 forms a very small proportion of living mammals. 



There are two groups of this order, the product of two lines 

 of descent. The Old World group contains the Aard Yarks 

 {Orycteropus) of Africa, and the Pangolins (Jl/a^^s) of Africa and 

 Asia. A gigantic ancestor of the latter is the Macrotheriutn of 

 the European Miocene. The New World group consists of the 

 Sloths, the Armadillos and the Ant-eaters. ]N^o fossil Edentates 

 liave been surely found in the Eocene, but the Miocene and Plio- 

 cene of the Western States have yielded remains of huge forms, 

 Moropxis and Mor other ium^ for example. The order was well 

 represented in the Post-pliocene of the Southern States, but 

 culminated in the numerous gigantic species of the Post-pliocene 

 of South America, which continent is the present home of the 

 greatly reduced order. The fact of no Tertiary Edentates in 

 South America would indicate that the order populated that 

 continent, where it found a more congenial home, by migration 

 from North America. 



No. 46. [26] Megatherium Cuvieri, Desmarest. 



Tooth (cast). The gigantic fossil represented by this 

 specimen was first made known to the scientific world in 

 1789. Its skeleton was discovered in the Pampean (Pleis- 

 tocene) deposit, on the banks of the Luxan, near the citj- 

 of Buenos Ayres. Transmitted to Madrid, it was for more 

 than half a century a problem in comparative anatomy, 

 which the savans of Europe could not solve. The merit 

 of finally assigning a true position to this remarkable fossil 

 belongs to the celebrated English Geologist, Professor 

 Owen. He" conclusively proved that the Megatherium was 

 a "Ground Sloth," and fed on the foliage of trees, up- 

 rooting them by its great strength, or pulling down the 

 branches with its formidable fore-arms, resting on its hind- 

 legs and tail as on a tripod. The mounted skeleton of the 

 Megatherium measures about 18 feet. It had 18 teeth, all 

 molars and in structure like those of the living Sloth. 

 They were long, square, slightly curved prisms with 

 wedge-like crowns, and consisted of dentine enclosed by 

 a wall of cement. The original of this tooth belongs to 

 the British Museum. Size, 7x2. 



