Crabs, Lobsters, Shrimps, Barnacles, etc. 



69 



ing. Behind the foot-jaws we find five pairs of walking'-legs, the first 

 three pairs of which end in pinching- claws. Tlie claws of the first pair 

 of these walking-leg-s are of immense size and strength, and serve as 



Fig. 163. Homariis vulgaris, 'k nat. size. 



weapons of attaci< or defence. The tail also bears a pair of limbs on 

 each joint ; they are termed the swimming-legs, but serve in the female 

 Lobster to carry the eggs. 



If we observe the Lobster more carefnlly, it seems to be constantly 

 fanning itself with the feathery tassels on its foot-jaws, and often jierforms 

 similar movements with its abdominal legs. This is its method of breathing. 

 Jnst as man renews the air in his lungs by the contraction and expansion 

 of his chest, so the Lobster, by these movements of its feet, causes fi'esh 

 water to flow to its gills, which lie under its shell at the base of the 

 legs. Anotlier noticeable action is the constant twitching of the smaller 

 pair of feelers; these probably serve as olfactory organs, Avhile the larger 

 ones are the org-ans of touch. 



An important event in the life of a crab or lobster is the annual 

 moult, when the animal literally creeps out of its shell, or as one might 

 say : « jumps out of its skin ». At these periods a crack makes its ap- 

 pearance at the hind end of the carapace, and through this the Lobster 

 lias to work its way out; first the tail, and then tiie head and body, 

 being witlidrawnfrom the old shell. It is a troublesome and often dangerous 

 operation, as all the appendages have to be drawn out, inchuling the 

 large claws, the eyes, the antennte and the jaws; even the wall of the 

 stomach has to be renewed ! Often the animals have to sacrifice one 

 or both claws, and they are in great danger Tintil the new covering has 

 hardened sufficiently; so they instinctively seek a |)lace of retreat du- 

 ring this ojieration. Uninjiired specimens which have just shed their 

 skin, look very handsome in their new and l)right apparel. 



Of the habits of the Lobster which can be observed in the Aqua- 



