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 _Palæmon_, 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 XXI.), which reaches a length of 10 inches exclusive of the great claws, is sold in the markets, while in India and elsewhere in the East _P. carcinus_, which grows to an even greater size, and other smaller species, are used for food. The fresh-water Prawns of the family Atyidæ, on account of their small size, are not of much importance from this point of view, but Professor Hickson states that the little _Caridina nilotica_, a very widely-distributed species, is eaten in Celebes. [Illustration: _PLATE XXXI_ THE COMMON EDIBLE CRAB, _Cancer pagurus_. BRITISH. (MUCH REDUCED)] Among British Crustacea, the next in importance to the Lobster as an article of food is the Edible Crab, _Cancer pagurus_ (Plate XXXI.), 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 10 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 importance on many parts of the British coasts. On the other hand, a Connemara fisherman, who was using these Crabs for bait, received with incredulity the statement that they were good for human food! The Shore Crab, _Carcinus mænas_ (Plate IX.), is not of much importance as food in this country, although it is recorded that fifty years ago great numbers were brought to the London market. On the shores of the Mediterranean and Adriatic, however, and especially in Venice, this species is regarded as a delicacy, particularly in the soft-shelled state after moulting. On the Atlantic coast of North America, the most important edible Crustacean after the Lobster is the "Blue Crab" (_Callinectes sapidus_), one of the Swimming Crabs (Portunidæ). This is consumed in large quantities, especially in the soft-shelled state. Several other species of Crabs are eaten in America, including the little "Oyster Crab," a species of _Pinnotheres_ living in the American Oyster. From its small size, and the difficulty of obtaining it in numbers, it is a very costly delicacy. In the East Indies the most important edible Crabs are various species of Portunidæ, especially the large _Scylla serrata_ and _Neptunus pelagicus_.