LOBSTEE OE CRAYFISH 167 



the former usually carried ? In what the lat- 

 ter ? What advantages arise from these move- 

 ments ? Is the scale-like appendage of the an- 

 tenna mobile? Examine the eyes. How great 

 is their range of motion ? Can the lobster look 

 backward? Down by its side? Upward? Can 

 it see what it is eating ? Can it close its eyes? 

 Are any of the movements such as to protect 

 the eyes? 



"Watch for the motions of the scaphognathite. 

 In what manner does it move ? At what rate ? 

 Of what use are its movements ? Can you 

 make out whether or not the gills move? 

 Does the branchiostegite ? 



h. Feeding. — If the lobster is studied, put small pieces 

 of meat, clam, bread, sea-weed, etc., in the aqua- 

 rium ; if the crayfish, use meat and bread. If 

 not too large, put the animal into a glass dish, so 

 that by holding it up you can see the motions of 

 the mouth parts. How does the animal seize its 

 food ? How convey it to the mouth ? "While 

 eating one piece will it seize another ? Attempt 

 to remove a piece which the animal is holding. 

 "What does it do? "What is the action of the 

 chelae ? Of the maxillipedes ? Of the maxillae ? 

 Is the food thoroughly chewed before being swal- 

 lowed ? Does the animal " wash down " its food 

 with a swallow of water ? 



Examine again the stomach of a dead specimen 

 in water and try to discover the action of the 

 various gastric ossicles, and how their action 

 supplements the work of the jaws. After food 

 has once been swallowed, what prevents it from 



