Il8 W. J. CROZIER. 



when the tide recedes. Since they are not strongly photopositive, 

 they are seldom exposed to the drying action of the sun, and sur- 

 vive the temporary absence of water. Occasionally they have 

 been found killed by rain (this has also been seen with Stichopus 

 m&bii) . 



I always noticed that in the breeding months the proportion of 

 animals which seemed to have recently undergone self division 

 was much less than during the summer. Some attempt was 

 therefore made to discover the percentage of recently divided 

 specimens obtainable in each month of the year. This was done, 

 somewhat unsystematically, for several years. The result is set 

 forth in Table II. The data for each two-month period might 

 have been averaged together, thus perhaps obliterating to some 



TABLE II. 



THE PERCENTAGE OF " NON-REGENERATING " COSCINASTERIAS SECURED IN 

 RANDOM COLLECTIONS DURING EACH MONTH, 1915-1918. 



Total No. of Not Recently Di. 



Period. Individuals vided, Per Cent- 



January 74 59 



February 60 63 



March 35 60 



April 3 40 



May 34 : 7 



June 1 8 ii 



July 113 I2 



August 74 33 



September 4 2O 



October 32 4* 



November 27 33 



December 20 75 



extent the possible variation from year to year. The numbers in 

 the last column of the table express for each period the per- 

 centages in which the rays were 5 to 9 in number and of approxi- 

 mately equal length in other words, those which exhibited no 

 evidence of reasonably recent self division. 



For June-July-August, 1913 and 1914, I found (Crozier, '15) 

 83.6 per cent, of the individuals to exhibit a group of longer and 



spina, however, the tips of the rays shorten noticeably when a shadow is cast 

 on them alone, whereas in sunlight the tips of the rays tend to be curled 

 upward. 



