138 



Notwithstanding the delicacy of the shell, it is pro- 

 cured fossil. 



Found in streams, ditches, lakes, risers, and moun- 

 tain tarns. 



Some of the species are amphibious. 



A curious property of walking which the house fly 

 [Musca domestica] possesses is very remarkable, yet so 

 familiar are we with the fact that we do not give our 

 attention sufficiently to it ; I mean that it not only 

 walks in the ordinary manner, as on a table, but walks 

 as easily head downwards on the ceiling of a room. A 

 similar property belongs to this family of molluscs, for 

 it as easily crawls upside down on the surface of the 

 water, basking in the sun, as it moves in the ordinary 

 manner on the surface of the mud. 



The eggs are deposited in a glutinous mass, and are 

 attached to stones, or submerged leaves and stems of 

 aquatic plants. 



LiMNiEus AURicuLARius [The Widc-moutbed Mud 

 Shell]. LinncBus. 



Figure 103. 



102 



More closely allied to Limnjeus pereger than to any 

 other species, nevertheless it is easily distinguished 

 from that shell. It is much broader than L. pereger. 



