180 LESLIE B. ABEY AND W. J. CROZIER 



animals tend to occur in isolated groups, and further from high- 

 water level than the younger individuals, there results a type of 

 segregation which is favorable to the occurrence of some degree 

 of homogamy (assortive fertilization). This would result in the 

 economical utilization of sperms, and might possibly have ad- 

 ditional effects of an 'adaptive' kind. Some further correlation 

 between habitat and breeding habits in other chitons have been 

 noted by Heath (05 c, 07). 



[CPH-Pop(s,pKoto-3 



Fig. 9 A group of Chitons in a shallow depression. X h 



8. Bionomic correlations 



Chiton tuberculatus is strictly intertidal in habitat. It, there- 

 fore, becomes possible to examine the details of its natural 

 history rather extensively. The complexity of the catenary 

 systems of relations revealed by such examination renders 

 orderly description difficult. Some of these relations we have 

 referred to in the preceding sections. Numerous others remain 



