230 ECHINODERMATA 



modified in certain regards for special habits. Compare, for 

 instance, the feeding habits of the starfish, sea urchin, and 

 sea cucumber. 



Crozier, W. J.: The Orientation of a Holothurian by Light. Am. Jour. 

 Physiology, vol. 37, 1921. 



Kille, F. R.: Regeneration in Thyone briareus Lesueur following in- 

 duced autotomy. Biol. Bull., 69, 1935. 



van der Heyde: Hemoglobin in Thyone briareus lesueur. Biol. Bull., 

 vol. 42, 1922. 



