Among the pupils of Coysevox were Nicolas and Guillaume Coustou.
See Henry Jouin, A. Coysevox, sa vie, son œuvre (1883); Jean du Seigneur, Revue universelle des arts, vol. i. (1855), pp. 32 et seq.
CRAB (Ger. Krabbe, Krebs), a name applied to the Crustacea of the order Brachyura, and to other forms, especially of the order Anomura, which resemble them more or less closely in appearance and habits.
The Brachyura, or true crabs, are distinguished from the long-tailed lobsters and shrimps which form the order Macrura, by the fact that the abdomen or tail is of small size and is carried folded up under the body. In most of them the body is transversely oval or triangular in outline and more or less flattened, and is covered by a hard shell, the carapace. There are five pairs of legs. The first pair end in nippers or chelae and are usually much more massive than the others which are used in walking or swimming. The eyes are set on movable stalks and can be withdrawn into sockets in the front part of the carapace. There are six pairs of jaws and foot-jaws (maxillipeds) enclosed within a “buccal cavern,” the opening of which is covered by the broad and flattened third pair of foot-jaws. The abdomen is usually narrow and triangular in the males, but in the females it is broad and rounded and bears appendages to which the eggs are attached after spawning (fig. 1).
| Fig. 1.—Side view of Crab (Morse), the abdomen extended and carrying a mass of eggs beneath it; e, eggs. |
| Fig. 2.—Zoëa of Common Shore-Crab in its second stage. r, Rostral spine; s, Dorsal spine; m, Maxillipeds; t, Buds of thoracic feet; a, Abdomen. (Spence Bate.) |
As in most Crustacea, the young of nearly all crabs, when newly hatched, are very different from their parents. The first larval stage is known as a Zoëa, this name having been given to it when it was believed by naturalists to be a distinct and independent species of animal. The Zoëa is a minute transparent organism, swimming at the surface of the sea. It has a rounded body, armed with long spines, and a long segmented tail. The eyes are large but not set on stalks, the legs are not yet developed, and the foot-jaws form swimming paddles. After casting its skin several times as it grows in size, the young crab passes into a stage known as the Megalopa (fig. 2), also formerly regarded as an independent animal, in which the body and limbs are more crab-like, but the abdomen is large and not filled up. After a further moult the animal assumes a form very similar to that of the adult. There are a few crabs, living on land or in fresh water, which do not pass through a metamorphosis but leave the egg as miniature adults.
Most crabs live in the sea, and even the land-crabs, which are abundant in tropical countries, nearly all visit the sea occasionally and pass through their early stages in it. Many shore-crabs living between tide-marks are more or less amphibious, and the river-crab of southern Europe or Lenten crab (Potamon edule, better known as Thelphusa fluviatilis) is an example of the freshwater crabs which are abundant in most of the warmer regions of the world. As a rule, crabs breathe by gills, which are lodged in a pair of cavities at the sides of the carapace, but in the true land-crabs the cavities become enlarged and modified so as to act as lungs for breathing air.