-83- 



be observed. Tna tube feet will alljooordinate pointing in the 

 direction of the initiating rays and' the other ray a will move 

 so as to oome more at right angles to tho direction of the 

 tub* feet. The <aim on the right will twist to the right, Tnd 

 more over in the direction of the initiating raya. The ana 

 on the left will twiat to the left and do the same tiling* ihe 

 arm directly opposite the initiating arms will bend directly 

 over the disk and complete the somersault with locomotion, as 

 ws- shall show later, continuing generally in the direotion of the 

 initiating rays* This as we ahall see is perhape the moat common 



method of righting it tho disposal of the starfish* 



ing 

 Analysis ojf Penning* a Seven types of Hjgh/f reaQi.ion* 



Jennings (1907 pp. 125g ff } however, describes seven 

 sin ty]MM about which the extremely variable righting reaction 

 may be grouped. The first type is: 



l.*The simplest and neatest method is the following* X*o 

 adjacent rays twist their tips in suoh a way that the ventral 

 surface s of the two face each other* 'Ihen the tube feet of 

 these rays attach themselves and throw the starfish over in a 

 neat somersault** 



This is essentially the method described by me above* 

 Jennings description leaves out, hare, the coordinated action 

 ef the unattached arms thou^i he mentions it elsewhere in 

 general terms, and he does not recognize the aprea^ of the 

 coordination among the tube feet nor its relation to the 

 movements of the arms* As above stated this is the commonest 

 method of turning* We shall inquire as to the reason for the 

 turning of the rays toward each otfesr in a majority of oases 

 in connection with our discussion of the righting of the 

 oriented starfish* 



