86 VERTEBRATES : MAMMALS. 



The Genus Echidna comprises those which have a 

 long, slender muzzle and extensible tongue, like the Ant- 

 eaters, and which are covered with spines. 



The Genus Ornithorhynchus, or Platypiis, is character- 

 ized by an elongated, enlarged, and flat muzzle, present- 

 ing the closest external resemblance to the bill of a 

 duck, and the more so as its edges are similarly furnished 

 with small transverse laminae. These animals have no 

 teeth except at the bottom of the mouth, and these are 

 without roots, with flat crowns, and composed of little 

 vertical tubes. There is a membrane to the fore feet 



which not only unites the 

 toes, but extends far beyond 

 the nails ; in the hind feet 

 the membrane terminates 

 at the root of the nails, and 

 the tail is flat. The whole 

 body is covered with short, 

 brown fur. These animals 

 live in ponds and quiet 

 streams, and dig burrows 



Ornithorhynchus, or Platypus. . , , -, . 1*11 



in the banks, in which they 



rear their young. Only one or two species are known. 

 They are less than two feet in length. 



SUB-SECTION IX. 



THE ORDER OF PACHYDERMATA, OR PACHYDERMS. 



THE Order of Pachydermata comprises, according to 

 Cuvier, three families, Proboscidiana, Pachydermata Or- 

 dinaria, and Solipedes ; or, for each of these substituting 

 family names drawn respectively from a prominent genus, 

 or two genera in the second case, we may consider 

 the families as Elephantidae, or Elephant Family, Rhinoce- 

 ridae or Rhinoceros Family, Suidae or Swine Family, and 

 Equidae or Horse Family. They are all herbivorous. 



