3 1 4 Shell Life 



yellowish brown in colour, and its oval mouth has 

 a thickened outer lip. It is usually more or less 

 coated with mud, owing to its life being 

 spent in shallow pools, ditches, and bogs. 

 The animal leads a rather inactive life, and 

 resents disturbance. The shell measures 

 1 inch. 



The Dwarfed Limnsea (Z. truncatida) 

 might easily be taken on a superficial view 

 for a young specimen of L. j)Gil'^^tris, but 

 the whorls are turreted (that is, somewhat 

 flattened above) and with a nearer approach 

 to crlossiness. There is also a distinct umbilical cleft. 

 Its length is half an inch, and its habitat is on the 

 mud beside pools and ditches, where it appears 

 to feed on the low scum-like ahjoi that grow Bk 

 in such situations. We have found it near the M\ 

 base of Cornish cliffs within a foot of high- ^^ 

 water mark, and where it must have been con- uml^^, 

 stantly splashed by salt water. Fresh water 

 trickled througli cracks of the limestone and supplied 

 nourishment for a yellowish-green alga upon which 

 truncatida appeared to feed, and with which most of 

 the shells were coated. Viewed from the human 

 standpoint this species is the most important of the 

 whole order, for could it but be entirely exterminated 

 there would be some hope that Rot, that scourge 

 of the sheep-farmer, could be got rid of. It would 

 be foreign to the purpose of this volume to enter 

 fully into tlie history of the Liver Fluke (Disfoma 

 hepatlca) which causes this diseased condition of 

 the sheep, from which it is said no less than three 

 million animals perished in this countiy during the 



