Natural History 463 



infantile period being telescoped down, and the offspring are 

 able in five weeks to follow their mother and begin mining. The 

 full-grown males are very combative; indeed, there is a good 

 deal of suppressed fury in any mole. Everything they do is 

 done with vigour and zest moving, feeding, fighting, everything. 

 A mole has been known to displace a nine-pound brick on a 

 smooth surface, which for an animal weighing three ounces is 

 equivalent to a man of twelve stone moving an object weighing 

 3 tons 12 cwt. (Frances Pitt, Wild Creatures of Hedgerow and 

 Garden, 1920). 



The Mole's vigour must be correlated with its extraordinarily 

 good digestion. A mole can easily dispose of its own weight in 

 earthworms in a day, and adults require food every three or 

 four hours. A mole that was fed with forty earthworms late in 

 the afternoon was found dead next morning with an empty 

 stomach ! 



6 

 Arboreal Mammals 



Whether the earliest mammals were arboreal or not, it is a 

 mode of life which many have adopted, and it has obvious advan- 

 tages of increasing the freedom of movement, of securing a 

 relatively safe retreat, and of making a nest a possibility. In 

 many cases, as in a wild cat, the sharp claws are well suited for 

 holding on to the branches. The Squirrel runs up the trunk, 

 gripping with its claws, but looking as if it did not need to hold 

 on; and its bushy tail is of use as a rudder when it takes an 

 adventurous leap from tree to tree. In some cases, however, 

 there are specially attaching structures; thus the extraordinary 

 lemur called the Tarsius Spectre has disc-like suckers on its 

 fingers and toes. Sometimes there is a splitting of the hand 

 and foot which gives the limb a secure grip of the branch, and 

 the same result may be reached by having an opposable first 

 digit, like our own thumb. The Tree-Sloths show yet another 

 method, for their claws are greatly elongated into hooks, and by 



