176 LESLIE B. AEEY AND W. J. CROZIER 



'anticipatory' creeping toward the rising water of the incoming 

 tide, based upon some form of hydrotropism, might be dis- 

 covered in Chiton, and was accordingly looked for. None was 

 found. Chiton is in this regard analogous to the actinians 

 (Parker, '17 b); there is no 'memory' of recurring tidal events. 



Having in mind the possible metabolic basis of tidal rhythms 

 in behavior, discussed in connection with feeding and respiration, 

 the behavior of Chiton has been studied for the occurrence of 

 other tidal rhythms — inactivity as to creeping, movement out 

 of water, and the like. Nothing of this kind seems to occur in 

 C. tuberculatus. 



Chiton, unlike a limpet, does not settle down into a de- 

 pression closely conforming in outline to the impression of its 

 shell. Neither does it, hke a limpet, leave evidence upon the 

 rock surface of wanderings and returnings to a 'home station' 

 (Orton, '14). Inasmuch as a number of chitons seemed always 

 to be present in certain depressions, or 'pockets,' which were ex- 

 amined at low tides, and since observation of the behavior of 

 other chitons showed that they usually began to move about as 

 soon as the rising tide had wetted them, data were sought to 

 answer the question as to whether chiton exhibits in one form or 

 another 'homing habits' of the type which have been described 

 for Patella and its allies (Kafka, '14). 

 . An experiment of this sort is here recorded : 



June 15, 1914. Observations were restricted to a definite area of 

 smooth rocks below the boat house on Agar's Island. The chitons 

 were marked for subsequent recognition by means of a deep notch 

 cut in the girdle on either side of the body. (As noted elsewhere, 

 about four weeks were required for such notches to be even par- 

 tially obliterated through regeneration.) In the area of shore con- 

 cerned in this record there were several deep crevices and niches into 

 which chitons crept. The observations begun at this date were con- 

 tinued until July 14 (see table 1). 



This table shows plainly that for a period of twenty-six days 

 no material additions were made to the chiton population of this 

 particular section of the shore, although it did appear that there 

 were occasional new arrivals. In all, twenty-four chitons were 

 marked, and at the end of the experim.ent, twenty-four days after 



