Movement and Problem Solving in Ophnira 213 



progression may be of a very violent character involving many 

 contacts and much crossing of arms, or the animal may simply 

 w^rithe, without changing its location. If it does not move about, 

 it usually waves one of its arms, especially the encumbered, in a 

 horizontal plane, though the movements may also occur in a 

 vertical plane and in circles. The encumbered arm is moved in 

 a vertical plane oftenerthan the unencumbered ones; is frequently 

 rubbed against the disc; against the adjacent arms; against the 

 sides of the dish; and even against itself. Sometimes the encum- 

 bered arm is waved over the disc, much as a man waves a long 

 whip, and then is "cracked," so that the encumbering tube moves 

 nearer the distal end, and often slides off. When relieved the 

 animal usually does not remain quiet, but continues its move- 

 ments for a short time and makes several strokes that remove 

 it from the place where the tube was gotten rid of. If at the 

 instant of riddance the animal was not progressing, a short journey 

 is begun at the moment of relief. 



When encumbered on more than one arm, the latent period is 

 longer than when only one arm is encumbered; the first move- 

 ments are not through as great arcs, nor are they so long continued 

 in any direction. One movement is succeeded rapidly, not by its 

 duplicate, but by another in a different direction, and this by still 

 another. The behavior changes constantly. 



If all of the arms are encumbered, the above changes in behavior 

 cease very soon, and an entirely different kind of action is begun. 

 Instead of movements in the usual sweeping manner, the arms 

 quiver and tremble. In one case, one arm (the first to be rid of its 

 rubber tube) in particular attracted my attention by quivering 

 when the rest of the animal was perfectly quiet. These quivering 

 movements occur in a horizontal plane, and are so rapid, and 

 many of them so slight, that it is impossible to record them accu- 

 rately without special apparatus. 



Of all these movements, several are more effective than many 

 others in bringing about riddance. The most effective are the 

 "whip movement," the "stripping movements;" certain of the 

 "wavings," and violent progression which involves a number of 

 different movements. Of these the whip movement is the rarest; 



