196 VIGNETTES FROM NATURE. 



All ancient types which still linger on as 

 burrowers or nocturnal prowlers in the great 

 continents, like our own moles and shrews 

 and hedgehogs, have also a very low grade 

 of intelligence, and a very poorly developed 

 brain. But as we rise toward the summit of 

 each great specialised and differentiated line 

 of modern mammals, we find a constant 

 increase in intelligence and brain-power, 

 exactly analogous to that which we can trace 

 historically in the horse tribe. The central 

 and least developed forms, like the rodents 

 and still more the insectivores, are compara- 

 tively stupid and helpless ; but the highly 

 adapted creatures which represent the final 

 outcome of the main divergent branches, such 

 as the ungulates, the carnivores, and the 

 quadrumana, are all remarkable for their ex- 

 ceptional intelligence. Of these crowning 

 species, the horse and the donkey stand at 

 the head of their own line, just as man stands 

 at the head of the quadrumana, or as the 

 elephant and the tiger stand at the head of 



