VERTEBRATA : MAMMALIA. 



6 57 



thorhynchus and Echidna (or Tachyglossus) the one repre- 

 sented by a single species (O. paradoxus or anatinus), and the 



Fig- 357. Osteology of Monotremes. A, Skull of Echidna hystrix. B, Side view of 

 the skull of OrnitJwrhynchus anatinus, and C, lower jaw of the same, viewed from 

 above, showing the horny dental plates (m). D, Sternum and adjacent parts of the 

 skeleton of a young Ornithorhynchus : c c Clavicles; z Interclavicle ; p Prsester- 

 num ; ms, Mesosternum ; r r Vertebral ribs ; ir Intermediate ribs ; sr Sternal ribs. 

 (A, B, and C are after Giebel ; D is after Flower.) 



other by four species (E..hystrix, E. setosa, E. Lawesi, and E. 

 Bruijnii). All are exclusively confined to the Australian 

 province. 



The Ornithorhynchus or Duck-mole is one of the most ex- 

 traordinary of Mammals. The body (fig. 358) resembles that 



Fig. 358. Ornithorhynchus anatinus. 



of a mole or small otter, and is covered with a close, short, 

 brown fur. The tail is broad and flattened. The jaws are 



2 T 



