The carapace is long and convex, scarcely extending over the basal joints of the feet. The claw feet are short, with a very broad hand and sharp pincers; but the Hermit crab and some of its congeners are irregularly formed; for the last pair of walking feet, instead of being attached to the thorax, like the others, are fixed to the first part of the tail, are generally folded over the back, and are employed to sweep foreign matter out of the gills. The mouth and its masticating organs are similar to those in the crab, except the exterior pair of foot-jaws, which are longer and move like feet. But that which distinguishes the Pagurus and its fellows from every other Decapod is the softness of its unsymmetrical tail, all the appendages of which are abortive, and the extremity, instead of ending in a swimming fin, terminates in a pair of grasping organs. In order to protect this soft-skinned tail, the Hermit crab folds it up and thrusts it into some old empty shell, clasps the column of the shell with its grasping organs, draws in the rest of its body, and covers it with the broad hands folded in such a manner as to close the mouth of the shell, and to defend itself if attacked. It holds so fast that it cannot be drawn out; but, when in search of food, it stretches out its mailed head and legs, and walks off with its house on its back. However, it sometimes comes out of its shell to feed, and, like some other crustaceans, it holds its prey with one claw, and tears it to pieces with the other. They are very pugnacious, and come out of their shells to die. The larvæ of the Paguridæ undergo transformation, and they moult when full grown. _Stomapoda._