The remaining Crabs form the tribe _Brachygnatha_, in which the mouth-frame and the maxillipeds that close it are more or less quadrilateral in shape. The tribe is divided into two subtribes, which may be recognized by the general shape of the carapace. In the _Brachyrhyncha_ this is generally rounded or square-cut in front, without a projecting rostrum. In this subtribe are included the great majority of Crabs. The Edible Crab and the Shore Crab (Plate IX.) are familiar examples. In the _Oxyrhyncha_, on the other hand, the carapace is generally narrowed in front, with a projecting rostrum, either simple or forked, and is often armed with spines. In this subtribe are included the long-legged Spider Crabs, several species of which are common on our coasts. The Giant Spider Crab of Japan (Plate XI.) is the largest of living Crustacea. [Illustration: _PLATE XI_ THE GIANT JAPANESE CRAB, _Macrocheira kæmpferi_, MALE. THE SCALE OF THE FIGURE IS GIVEN BY A TWO-FOOT RULE PLACED BELOW THE SPECIMEN (_From Brit. Mus. Guide_)] The last division of the Eumalacostraca, the HOPLOCARIDA (Plate XII.), is one of very small extent, comprising only a single order (_Stomatopoda_) of very remarkable Crustacea which are common in tropical seas, and of which at least one species, _Squilla desmarestii_, is occasionally captured on the south coast of England. The Stomatopoda are prawn-like Crustaceans, usually with a flattened body, and are easily recognized by the form of the large claws (the second pair of thoracic limbs), in which the last segment shuts down, like the blade of a pocket-knife, on the preceding segment, and forms a very efficient weapon, so that the larger species are not to be handled without caution. The resemblance of these claws to those of the mantis-insect of Southern Europe led to a common Mediterranean species receiving long ago the name _Squilla mantis_ (Plate XII.). [Illustration: _PLATE XII_ _Squilla mantis_, FROM THE MEDITERRANEAN. ABOUT ONE-HALF NATURAL SIZE (_From Brit. Mus. Guide_)] The Stomatopoda have a small carapace, which does not cover the last four thoracic somites, and has in front a small flattened rostrum, attached by a movable hinge, like that of the Leptostraca. The eyes are stalked, and, like the antennules, are attached to a separate movable segment of the front part of the head--a peculiarity not found in any other Crustacea. There are small plate-like gills attached to the bases of some of the thoracic limbs, but the chief organs of respiration are large feathery gills attached to the pleopods or swimmerets. The Stomatopoda are all found in the sea, generally in shallow water, burrowing in sand or hiding in crevices of rocks or corals. Some species are more than a foot in length. CHAPTER IV THE METAMORPHOSES OF CRUSTACEA