EDENTATA. 539 



sion only when absolutely compelled to do so Whilst the 

 name of " Sloth " may thus appear to be a merited one from 

 the point of view of a terrestrial Mammal, it is wholly unde- 

 served when the animal is looked upon as especially adapted for 

 an arboreal existence. In the Ai or Three-toed Sloth {Brady- 

 pus tridactylus) there are three toes to each foot, and these are 

 short, completely rigid, and so enveloped in the integument 

 as to leave nothing visible except the enormously long and 

 crooked claws. The hand and foot are jointed to the arm 

 and leg obliquely, so that the palm and sole cannot be applied 

 to the ground, but are turned inwards. The ungual pha- 

 langes are also so articulated that the claws are bent inwards 

 towards the palm or sole. There are sixteen pairs of ribs. 

 The molars are rootless, growing frora permanent pulps, and 

 consisting of a simple cylinder of dentine enveloped in enamel. 

 In the Unau ( Cholcepus) the feet are two-toed, and there are 

 twenty-three pairs of ribs, the greatest number known in the 

 Mammals. 



The second family of the Edentata is that of the Dasypodida 

 or Armadillos. These are found exclusively in South Afnerica, 

 as are the Sloths, but they are very different in their habits. 

 The Armadillos are burrowing animals, furnished with strong 

 digging-claws and wfeU-developed collar-bones. The jaws are 

 provided with numerous simple molars, which attain the enor- 

 mous number of nearly one hundred in the great Armadillo 

 {Dasypus gigas). The upper surface of the body is covered 

 with a coat of mail, formed of hard bony plates or shields, 

 united at their edges. A portion of this armour covers the 

 head and shoulders, and another portion protects the hind- 

 quarters ; whilst between these is a variable niimber of. mov- 

 able bands which run transversely across the body, and give 

 the necessary flexibility to this singular dermoskeleton. In 

 some species this flexibility is so great that the animal can roll 

 itself up like a hedgehog. The tail is likewise mostly covered 

 with bony scutes. 



The Armadillos are confined entirely to South America, 

 ranging from Mexico to Patagonia. In this country, also, have 

 been found the remains of a gigantic armour-plated animal 

 allied to the Armadillos, which will be subsequently described 

 under the name of the Glyptodon. Amongst the best-known 

 species of Armadillo are the Peba {Dasypiis Pebd), the Poyou 

 {D. sexcinctus), the Tatouay (23. Tateuay), and the Great Knaz.- 

 &\!\o{D. gigas). A somewhat aberrant form is the Chlamyphorvs 

 (fig. 209) of South America, the total length of which is only 

 about six inches. , 



