M ASK.-UH AB. Corystes Cassivelaunus. 



POLISHED CRAB. Tliia polita. 



The antennse are apt to become clogged with mud, and the crab is therefore gifted 

 with an apparatus whereby they can be perfectly cleansed. In order to effect this object, 

 the crab bends each antenna sideways, until it rests on the hairy base of its companion ; 

 it then draws it completely through the stiff bristly hairs, until every particle of extra- 

 neous matter is brushed away. Sometimes the Mask-crab buries itself so deeply, that it 

 only leaves the tip. of the antenna above the sand. The name of Mask-crab is given to 

 this crustacean, because the carapace is so formed that its two waved grooves mould the 

 surface into an obscure likeness of the human face. This resemblance may be seen by 

 reference to the left-hand figure. 



The smaller figure on the right hand is the POLISHED CRAB, so called from the smooth, 

 shining surface of the carapace. In this genus the carapace is somewhat heart-shaped, 

 and very narrow behind ; the claw-feet are small and short. Although this is one of the 

 British species, it is not very commonly found, probably on account of its habit of burying 

 itself rather deeply in the sand, so that the eye cannot perceive it, and the dredge passes 

 over its sunken body without sweeping it into the net. It is rather a pretty little crab, 

 though unfortunately its beauty is only skin-deep, and perishes after death. When 

 living and in good health, the carapace is of a soft rose colour, and has a very pleasing 

 appearance ; but when the shell is emptied of its contents, or even after the death of the 

 inhabitant, the pink hue rapidly fades into the dull greys so prevalent among dead 

 crustaceans. In the Mediterranean the Polished Crab is very plentiful, and it is possible 

 that if the British coasts were thoroughly searched, the Polished Crab would be found in 

 tolerable plenty. 



WE now come to another family, of which the WOOLLY CRAB is an excellent type. 



This creature derives its name from the coating of thick short hair with which its 

 body is covered. All the species of this genus possess several peculiarities ; at each side 

 of the shell, and just at the base of the claw-legs, is an aperture that looks as if it had 

 been cut for a button-hole, and partly closed with a membrane. These apertures are in 

 fact the openings through which the water passes for the purpose of supplying the gills 

 with the needful moisture, and allowing it to escape when it has performed that office. 



