400 



Dana has reduced this family to the rank of a sub-family, 

 and has separated Niscea and Campecopea, as a sub-family, 

 from the remainder of the genera. 



The species of this family frequent the rocky shores 

 of the ocean, amongst Thalassiophytce, or under stones 

 and along the muddy banks of estuaries. Others, how- 

 ever, are generally found adhering to marine plants 

 floating on the surface of the sea, and some exotic 

 species eat deeply into water-logged timber, like Limnoria. 

 They are able to run and swim with considerable agility, 

 and afford a large supply of food to fishes. 



