CHAPTER XIII 

 THE JOINTED-FOOT ANIMALS: ARTHROPODA 



The Shelly Crawlers each returning year 



Cast off their shells and new-made Armour wear. 



OPPIAX, Ilalleutica. 



THE ALLIES OF THE CRAYFISH : CRUSTACEA 



The Lobster. Except for the considerable difference in 

 size, and the slight differences in the shape of the body, 

 the number of gills, and the structure of abdominal append- 

 ages, the description of the adult crayfish would serve for an 

 account of the structure of our common species of Ameri- 

 can lobster, Hom'arus america'nus. The lobster is found in 

 greatest numbers along the coast of Maine and the Canadian 

 maritime provinces. Toward the south the number gradu- 

 ally decreases to the Delaware breakwater, beyond which 

 they are very rare. In their days of greatest abundance 

 they grew to be about sixty centimeters (two feet) in length, 

 weighing twenty-five pounds, but with the increase in the 

 activity of the lobster-fishing industry they are now rarely to 

 be found weighing over two pounds. 



The lobster lives on the bottom. It is protectively colored, 

 but it does not depend wholly upon that condition for escap- 

 ing the notice of its enemies. In shallow waters lobsters are 

 known to conceal themselves beneath masses of brown sea- 

 weed in pits and holes, and also to find safe retreat beneath 

 jutting ledges of rock, where they rest with the abdomen 

 doubled beneath, ready to dart out and seize passing prey in 

 their claws. We have no way of knowing the exact habits 

 of the animal when at its greatest depth (a hundred fathoms), 



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