IDOTEA TRICUSPIDATA, 383 
the smaller crustacea and mussels very readily. It swims 
swiftly, and when at rest it generally clings to some sub- 
stance admitting of its supine position ; exuviation ensues 
at different seasons, the shell being always cast in two 
portions.” 
Mr. Robertson says that, like the herring, they are 
observed to grow to a larger size in Loch Fyne than on 
the neighbouring sea-coast. 
