THE SENSORY RESPONSES OF CHITON 



169 



2. Growth and duration of life 



As with animals in general, the rate of growth of Chiton de- 

 creases with advancing age. For the area considered in this 

 report the growth of Chiton tuberculatus appears to be ade- 

 quately represented in figure 5. A detailed analysis of the 

 material upon which this curve is founded will be given elsewhere. 



CD 



3 4 5 6 



Lengths, 



S crrfS. 



Fig. 5 Showing the relation between size (total length, in centimeters) and 

 estimated age (years) in Chiton tuberculatus. These est mates are not in- 

 tended to be of final significance. The normal average growth curve differs in 

 shape from that shown. The two lines shown include between them most of the 

 variations found in the Chiton population of Great Sound (April to May, 1918). 



The maximal duration of life seems normally to be from eight to 

 nine years (fig. 6) . A length of existence so great as this appears 

 not to have been suspected previously for the chitons. This 

 species probably comes to reproductive maturity in the second 

 (or third?) year of life (Crozier, '19). The general rate of growth 



