Crabs, Lobsters, Shrimps. Barnacles etc. 69 



of appendages or feet modified for purposes of mastication. Of these 

 first we have a pair of mandibles followed by two pairs of maxillae, 

 forming the "jaws" of the Lobster. Then there are three pairs of "foot- 



Eig. 163. Homarus vulgar is. i /.j nat. size. 



jaws" or maxillipedes , used by the animal to hold and turn about his 

 prey or food, while the jaws proper are employed for biting and chew- 

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

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

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

 weapons of attack 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 carefully, it seems to be constantly 

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

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

 Just 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 fresh 

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

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

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

 ones are the organs 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 

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

 being withdrawn from the old shell.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

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

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

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



