Chap. II. EXCAVATION OF THEIR BURROWS. 101 



anterior extremity of its body into any little 

 crevice, or hole ; and then, as Perrier re- 

 marks,* the pharynx is pushed forwards into 

 this part, which consequently swells and 

 pushes away the earth on all sides. The 

 anterior extremity thus serves as a wedge. 

 It also serves, as we have before seen, for 

 prehension and suction, and as a tactile organ. 

 A worm was placed on loose mould, and it 

 buried itself in between two and three 

 minutes. On another occasion four worms 

 disappeared in 15 minutes between the sides 

 of the pot and the earth, which had been 

 moderately pressed down. On a third oc- 

 casion three large worms and a small one 

 were placed on loose mould well mixed with 

 fine sand and firmly pressed down, and they 

 all disappeared, except the tail of one, in 

 35 minutes. On a fourth occasion six lar^e 

 worms were placed on argillaceous mud 

 mixed with sand firmly pressed down, and 

 they disappeared, except the extreme tips of 

 the tails of two of them, in 40 minutes. In 

 none of these cases, did the worms swallow, 

 as far as could be seen, any earth. They 



* ' Archives de Zoolog. exper.' torn. iii. 1874, p. 405. 



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