(ECOLOGY. 317 



brightly coloured or phosphorescent. Many Crustaceans 

 live on the shore, and play a notable part in the struggle 

 for existence which is so keen in that densely crowded 

 region. The lower Crustaceans are abundantly repre- 

 sented in fresh water, in pools, streams, and lakes. A 

 few Crustaceans, such as wood-lice and land-crabs, are 

 terrestrial, and some blind forms occur in caves. 



