OBSERVATIONAL LESSON IV 



43 



SUGGESTIONS FOR FURTHER WORK IN SCHOOL 

 Very gently move apart the structures which look like miniature 



" barn doors " and lie just in front of the places where the claws 



are attached to the body. 



Describe and sketch what 



you see within. 



The greater breadth of 



the tail in the female 



animal and the larger 



number of swimmerets 



with which she is pro- 

 vided (see figure 42) is a 



point that should not be 



overlooked. 



You may have won- 

 dered what was the cause 



of the bubbling that goes 



on just beneath the front 



of the crab's head when 



the creature is alive. In a 



dead specimen you can, by 



cutting away the "shell" 



at the sides, lay bare the F IGURE 42. The tail of a female edible crab extended to 



" balers" that are present show the swimmerets. 



at the sides of the mouth and the gills over which a constant flow 



of water is maintained when the crab is in the sea. 



