BILATERAL TENDENCIES IN PYCNOPODIA HELIENTHOIDES. 249 



with its pedicellariae and crawled away with it to deeper water, and 

 then started to feed on it there. In another instance, the star 

 started to feed on the dead crab at once. In so doing it put the 

 rays over the crab, tucking it under itself, rising on the tips of its 

 rays and in this way proceeded to devour its meal. In yet 

 another instance it was found that Pycnopodia was feeding on 

 other starfish (Evasterias troscehlii'), and this even though there 

 seemed to be plenty of gasteropods and other mollusks present. 

 It was also found to be feeding on Strongylocentrotus drbbachiensis. 

 Finally Pycnopodia feeds on porifera and on plants of the latter, 

 kelps and algae. This last kind of food is probably resorted to 

 when clams and gasteropods are beyond its reach. Because of 

 these various types of food that this starfish feeds on, it may 

 well be said that Pycnopodia is omnivorous in its habits of feeding. 



CONCLUSION ON MOVEMENTS IN GENERAL. 

 The fact that Pycnopodia always moves along one and the 

 same axis, with the same side always as anterior end; the fact 

 that it has a definite method of righting itself, as well as apparent 

 voluntary behavior during feeding, seems to point to dominating 

 bilateral symmetry rather than radial symmetry. With such 

 evidence of dominating bilateral symmetry, one should expect 

 a nervous system more complex than that of the ordinary starfish. 

 Indeed, something relative to experiments on the regenerative 

 powers of this genus seems to point that way. The regenerative 

 powers in Pycnopodia seems to be less than in the common 



starfish. 



M ERISTIC VARIATION. 



The Modal Curve. 



The modal point of rays in males, females and immature 

 specimens is represented in Fig. 4. That of the female, IIBB' 

 shows an abrupt demarcation, in that the average modal 

 point of number of rays is reached before maturity, while that 

 of the male fluctuates. This fluctuation, however, is the same 

 after the modal point is reached, but is of course greatest, 

 regardless of sex, among the immature, although that particular 

 number which was examined showed a modal point much the 

 same as that of the mature ones (Fig. 4, I A A', males; IIICC', 



