THE' RELATION OF THE MADREPORITE TO THE 

 PHYSIOLOGICAL ANTERIOR END IN THE 

 TWENTY-RAYED STARFISH, PYCNOPODIA HELI- 

 ANTHOIDES (STIMPSON).* 



H. P. KJERSCHOW-AGERSBORG. 

 TEN FIGURES IN THE TEXT. 



In a previous paper ('18) the writer recorded some facts con- 

 cerning the bilateral tendencies and habits in Pycnopodia Jicli- 

 anthoides. These were based on data gained from experimental 

 studies and on others from observations on the behavior of the 

 organism in its native environment. It was the writer's purpose 

 at that time to follow the paper of 1918 with one on the physiology 

 and histology, as well as other structural features of this species, 

 and for this reason certain points were omitted from the paper 

 mentioned above which might well have been included therein. 

 Owing, however, to the writer's remoteness from the Pacific coast 

 for the last five years and the lack of material on which to con- 

 clude this second work, it has been quite impossible for this ad- 

 ditional contribution to appear sooner. During the last summer 

 (1921) the writer was, however, so fortunate as to find opportunity 

 to visit Puget Sound and gather some additional information on 

 Pycnopodia. (It may be of interest to note in this connection that 

 the transplantation of Pycnopodia from Bremerton to West Seattle 

 was successful, which was shown by the fact that specimens of 

 various sizes were found on September 2, 1921, on the piles under 

 the docks at West Seattle, where about 12 specimens were planted 

 in the spring of 1915, notwithstanding the difference in salinity at 

 these two places. It was impossible, on account of lack of time, 

 to determine whether the specimens found at West Seattle, 1921, 

 were the same as those planted there in 1915, or whether they were 

 the progeny of the latter. Vide Kjerschow-Agersborg, 1918.) 

 From the additional data gathered this summer (1921) it is possi- 



* Contributions from the Zoological Laboratory of the University of Illi- 

 nois, No. 197. 



202 



