FOUND LINKS 135 



that bind the quadrupeds to their lower Vertebrate 

 neighbours. 



There can exist, at least, no doubt of the remark- 

 able likeness which the lowest quadrupeds present to 

 the bird and reptile groups. To understand thoroughly 

 the zoological aspects of the matter, I may remind the 

 reader that the class of mammals is very sharply split 

 into two main divisions. These, to avoid technicalities, 

 we may term Higher and Lower Mammals. The 

 former group includes forms ranging from man down- 

 wards through the apes, bats, rodents, and hoofed 

 quadrupeds, to the whales, sloths, anteaters, and their 



Fig. 6. Ornithorhynclms, or " Duck-billed Water-mole of 

 Australia " (showing the " bill " and webbed feet). 



kith and kin. These animals are distinguished by the 

 higher brain-structure and by the general possession 

 of all the typical characters of quadrupeds. The 

 Lower Mammals are the Ornithorhynchus, or " Duck- 

 billed Water-mole" of Australia (Fig. 6), and its 

 neighbours the Echidnas or " Porcupine Ant-eaters " 

 of Australia; these two genera forming the lowest 

 order (Monotrcmata) of all. A little above them, but 

 still shut off from the higher ranks of the class, are 



