2 HISTORY OF BRITISH CRUSTACEA. 



retail them by the dozen. These are the chief Crustacea 

 eaten in London, exclusive of thousands of the Shore Crab, 

 which may be seen, by the side of Whelks and Periwinkles, 

 on stalls in the poorer neighbourhoods, where they find ready 

 purchasers in many a ragged gourmand. 



The great Craw-fish, or Thorny Lobster, and a limited 

 number of the small fresh-water Cray-fish — in all, some 

 eight or ten species of Crustacea — exhaust the list of the 

 members of this class of animals, sold as food in our Metro- 

 polis. Although Crustacea directly do not greatly add to 

 our supplies of food, yet they indirectly assist very mate- 

 rially in contributing to our wants. The great mass of fish 

 derive their principal food from the smaller members of this 

 class, which swarm in our seas by myriads ; and, in this way, 

 Crustacea contribute greatly to our comfort. They are the 

 nutritious food not only of vast shoals of fish, but of swarms 

 of sea-birds, some of which feed almost exclusively on them, 

 particularly in the Arctic parts of the ocean. Crustacea also 

 form the bulk of the food which supports the vast bodies of 

 the Whale tribe, as may be seen somewhat further on, under 

 the description of the Mysidida, one of the families of the 

 order Stomapoda. The small terrestrial species, — such, for 

 instance, as the little Hog-lice of the genera Onucus and 



