166 THE BIOLOGY OF THE ANIMAL 



How rapidly can it swim? Has it any other 

 modes of locomotion than walking and swim- 

 ming ? Is its body adapted for rapid motions ? 

 For walking and swimming long distances ? 



1. Movements of the regions of the iody. — What re- 



gion of the body is most flexible ? In what 

 direction does it bend ? To what extent can it 

 bend in this direction ? Of what use is this 

 motion ? Can it bend in the opposite direction ? 

 Why? 



2. Movements of the appendages. — Examine each 



appendage separately. What motions have 

 the abdominal appendages ? Do all have the 

 same ? Is their range of movement very great ? 

 Of what use are their movements ? 



Of what movements are the last five cephalo- 

 thoracic appendages capable? Can you de- 

 scribe a circle with their tips ? By what sort 

 of joint are their segments connected? How 

 is it possible with this kind of joint to produce 

 the range of motion possessed by these append- 

 ages ? Notice the peg-shaped outgrowth upon 

 one of the basal joints of the chelae. Wha.t is 

 its use ? Study the movements of the dactylo- 

 podites. For what purposes are the various 

 forceps used? What are the motions of the 

 maxillipedes and the maxillae ? Is there any 

 advantage in this ? Turn the animal over on 

 its back. How does it right itself ? What ap- 

 pendages are used ? 



What difference between the lobster's jaws 

 and yours in their direction of motion ? 



In what different directions can the antennae 

 point ? The antennules ? In what position are 



