230 Shell Life 



its favourite resort is on dry hedge-banks, especially 

 on chalky soil. In dry weather, also in winter, it 

 partially buries itself, and in excavating a hole it 

 uses its proboscis for the removal of earth. When 

 climbing it is said to use this same organ as a hand 

 to take hold by. It is very shy, and withdraws into 

 its shell on the slisfhtest alarm, closingf its door and 

 dropping to the ground. This species and the next 

 are the only native land - snails that possess the 

 operculum, and its retention in so highly developed 

 a condition by the present species may be explained 

 not only by the nature of its breathing apparatus, 

 but by reference to its enemies. There is a small 

 beetle known as Driliis flavescens, and its larva or 

 grub devotes itself to the destruction of the Round- 

 mouthed Snail. This is how it effects its fell purpose 

 — in spite of the stony door that shuts out most 

 enemies. The Drilus-larva waits patiently at the 

 mouth of the snail's shell until the door opens and 

 the mollusk comes forth ; then it contrives to cut the 

 muscular attachment of the operculum, so that when 

 the snail withdraws the door of its fortress will not 

 close properly. The Drilus can now complete its 

 work at leisure ; it enters the shell and consumes 

 the body of the snail, then changes into the pupal 

 condition and waits within the shell until it has 

 attained to its final form as a complete beetle. 



There is one other native species included in the 

 same family, tliough it forms another genus. This 

 is the Point-shell (Acicida lineata), whose name 

 indicates, though it does not accurately describe, its 

 dimensions. Its form is cylindrical, with a slight 

 tapering to the upper end ; the whorls 6 or 7, 



