CHAP. II. CONSTRUCTION OF THEIR BURROWS. 113 



generally, or as I believe invariably, lined 

 with a thin layer of fine, dark-coloured earth 

 voided by the worms ; so that they must 

 at first be made a little wider than their 

 ultimate diameter. I have seen several 

 burrows in undisturbed sand thus lined at 

 a depth of 4 ft. 6 in. ; and others close 

 to the surface thus lined in recently dug 

 ground. The walls of fresh burrows are 

 often dotted with little globular pellets of 

 voided earth, still soft and viscid ; and these, 

 as it appears, are spread out on all sides by 

 the worm as it travels up or down its burrow. 

 The lining thus formed becomes very com- 

 pact and smooth when nearly dry, and 

 closely fits the worm's body. The minute 

 reflexed bristles which project in rows on 

 all sides from the body, thus have excellent 

 points of support ; and the burrow is rendered 

 well adapted for the rapid movement of the 

 animal. The lining appears also to strengthen 

 the walls, and perhaps saves the worm's body 

 from being scratched. I think so because 

 several burrows which passed through a layer 

 of sifted coal-cinders, spread over turf to a 

 thickness of 1 J inch, had been thus lined to an 



