120 Papers from the Department of Marine Biology. 



SUMMARY. 



1. Individual differences in the responses of crinoids to the various 



kinds of stimuli indicate a complex nervous mechanism and 

 forbid any simple explanation of their reactions. 



2. Important differences in the methods of locomotion and of 



feeding show that different groups of comatulids (genera, 

 families, orders, etc.) may give quite different responses to 

 identical stimuli. 



3. Many comatulids, especially the large multibrachiate species, 



are very sluggish, and the members of the family Comas- 

 teridse do not swim, but only creep about by use of the arms. 



4. Comatulids of the families Stephanometridse, Mariametridse, 



Colobometridse, and Antedonidse, although ordinarily inactive, 

 are good swimmers and do not creep as the usual method of 

 locomotion. 



5. It is doubtful if, under unchanged conditions, comatulids move 



about to any important extent, but it is certain that local 

 changes can, and do, bring about considerable alteration of 

 position and possibly real migrations. 



6. Comatulids at Mae'r during the dry season are almost exclusively 



vegetable feeders, although protozoans form a small part of 

 their nourishment. The food is not ingested as dead matter, 

 but is unquestionably taken in as living material. Feeding 

 is presumably accomplished by means of the ciliated furrows, 

 and movements of the arms are certainly not essential and 

 probably are not a very important factor. 



7. All the comatulids at Mae'r are negatively phototactic. Brightly 



lighted areas are avoided and shadowed or dark places are 

 sought. 



8. The comatulids at Mae'r show marked susceptibility to heat and 



an increase of only 2 degrees produces an evident effect. 

 Areas of markedly increased temperature are avoided. 



9. The comatulids of Mae'r showed no response to a marked decrease 



in the salinity of the water and none to a slight increase of 

 the salts. Their reaction to strong solutions of MgSO 4 is 

 noticeably different from that of other echinoderms. 



10. Reactions to strong alcohol or formalin are marked and well 



defined, and normally follow a regular sequence. 



11. Reactions to impure sea-water, presumably to the CO-2 contained 



in it, are slow but sure. An excess of impurity soon produces 

 inaction, followed ultimately by complete disintegration. 



