248 THE LIFE OF CRUSTACEA 



Numerous other species of Natantia are used for 

 food in various parts of the world, but the only ones 

 that need be further mentioned here are the River 

 Prawns of the genus Palcemon, which are abundant 

 in the fresh waters of most tropical countries, and 

 sometimes grow to a very large size. They are 

 generally distinguished by the fact that the legs of 

 the second pair are very long, forming powerful 

 pincer-claws. In the West Indies and Central 

 America, P. jamaicensis (Plate XXL), which reaches 

 a length of lo inches exclusive of the great claws, is 

 sold in the markets, while in India and elsewhere 

 in the East P. carcimis, which grows to an even 

 greater size, and other smaller species, are used for 

 food. The fresh-water Prawns of the family Atyidas, 

 on account of their small size, are not of much 

 importance from this point of view, but Professor 

 Hickson states that the little Caridina niloticay a very 

 widely-distributed species, is eaten in Celebes. 



Among British Crustacea, the next in importance 

 to the Lobster as an article of food is the Edible 

 Crab, Cancer pagurus (Plate XXXL), known in 

 Scotland as the " Partan." Like the Lobster, it is 

 found on rocky coasts in shallow water, and young 

 specimens are often taken between tide-marks. It 

 grows to a size of more than lo inches across the 

 shell, and may reach a weight of 12 pounds. The 

 means used for its capture are the same as in the 

 case of the Lobster, and the fishery is of considerable 



