8 Adams, On the Mole {Talpa eiiropcea). 



the whole heap made entirely by this tunnel. Fig. 9 



Fig. 8. — N\. — Old nest with 2 bolt-runs. Fig. 9. — a. — tunnel by which the 



N 2. — New nest. entire heap was formed. 



C — Upward tunnel by which i, 2, 3, 4, 5,6, 7. — Outlets direct 



the entire heap was from the nest, 

 formed. 



illustrates a low fortress on boggy ground, the wiiole 

 heap being formed by a single tunnel {a) leading 

 upwards from the nest. This nest had seven outlets just 

 below the soil. There was no other tunnel or bolt-run. 

 When this superincumbent earth has reached an in- 

 convenient height another tunnel is made, sometimes 

 from another part of the nest-cavity {Figs 1, 2, a, d), but 

 more often sideways from the first upward tunnel. All 

 this takes time, and the mole meanwhile makes fresh runs 

 from the fortress, the seat of its labour, in various directions 

 in search of food. Much of the earth displaced in making 

 these fresh runs falls into the nest-cavity, and has to be 

 disposed of in the same way as before, and also the soil 

 displaced in making the bolt-run (see p. 13) and the 

 downshaft (see p. 13) when this latter occurs. Now the 

 tunnel (or tunnels) leading upwards from the nest-cavit)- 

 becomes longer and longer, winding round under the 

 surface of the growing fortress. When this removal of 



