G@COLOGY. 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. 
