THE CRAYFISH AND THE CRAB. 



Though the greater part of the lesaoDS on the lobster applies 

 equally well to the crayfish (?ig. 1), still, for the sake of those who 

 will make nse of the latter alone, a few more points may well be 

 bronght ont here. 



The crab (Fig. 2) deserves oar attention not only beoanse it is so 

 common and easily obtained, bnt also becanse it famishes a strik- 

 ing instance that children can appreciate of the changes in an an- 

 imal bronght aboat by change of habit, even when the general plan 

 of strnotnre remains the same. Those who can proonre both the 

 lobster and the crayfish may devote one lesson to a comparison of 

 the two as a review of this important type of stractnre, when chil- 

 dren's qnick eyes will discover many minitn points of resemblance 



Fig. 1 

 or difference that it is unnecessary to tonch npon here. It will of 

 coarse be impossible in practice to combine the crayfish and the 

 crab in one lesson, as is done in this ontline. 



The home of the crayfish is in fresh-water streams, 

 where it is most active towards evening, seeking shelter 

 from the heat and sunshine of the day under the shade of 

 stones and banks. In the winter it burrows in the banks, 

 not to sleep, however, for on warm days it lies at the 

 mouth of its burrow watching for food. Like its salt- 



