Table 7. --Increase in length of overall molting period with increase 



in age of the northern fur seal""" 



For each age and sex class there is shown the total period during which 

 some seals were in molt. 



Total 316 seals, including seals not in molt but taken during the molting 

 period for the year class. 



^ Mean age of males 6.4 years; of females 7.4; of both 7.1. 

 ^ Mean age of males 11.0 years; of females 12.3; of both 12.1. 



from 2 to 73 percent (mean 28.5) of the units 

 contain twin hairs. In ending molt, the percent- 

 age drops to less than 2; over 98 percent of 

 the units contain a single hair. No satisfactory 

 way of identifying the maturehair stump at this 

 stage as either new or old generation has been 

 found. In the resting stage which follows molt 



and extends for 8 or 9 months, no twin hair 

 stumps can be seen. In other words, as a new 

 hair develops fully, the old one is shed. 



The data in table 8 show not only variation 

 in percentage of twin hairs with stage of molt, 

 but also with age of seal. They suggest an 



16 



