PLATE VIII

THE "NORTHERN STONE-CRAB," Lithodes maia, MUCH REDUCED. THE LAST PAIR OF LEGS ARE FOLDED OUT OF SIGHT IN THE GILL CHAMBERS

(From Brit. Mus. Guide)

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The Hippidea are curious little Crabs found burrowing in sandy beaches in the warmer seas. They have the abdomen tucked under the body, and the legs flattened for shovelling the sand.

The Brachyura, or true Crabs, form the fourth section of the Reptantia, and are distinguished by having the abdomen reduced to a tail-flap, which is doubled up under the cephalothorax, and is usually without any trace of the uropods which are present in all the groups already mentioned, with the single exception of the Lithodidæ. At the sides of the head the side-plates of the carapace become firmly soldered to the "epistome," a plate which lies in front of the mouth, and in this way there is formed the "mouth-frame," within which lie the jaws, covered in by a pair of "folding-doors" formed by the flattened third maxillipeds.

PLATE IX

THE COMMON SHORE-CRAB (Carcinus mænas). (REDUCED)