292 



Anal Fin. — Five out of 116 first year specimens have one anal spine; 6 out 

 of 236 of the second year, and 3 out of 246 of the oldest specimens. 



The average number of anal rays are 10.56 for the first year, 10.74 for the 

 second year and 11.00 for the third year specimens. 



The curves in Fig. 7 and Table IX, below, show that the anal fins of the first 

 and second year specimens more nearly resemble each other. All three ages show 

 a preference for 11.00 rays. The per cent, of specimens having this number are 

 51.69, 52.53 and 61.60 for the first, second and third year specimens respectively. 

 The per cent, of siJecimens having 10 rays is reduced from 36.43 in the first year to 

 2". 57 in the third year, and the per cent, of those having 12 rays is increased 

 from 5.09 in the first year to 20.16 in the third year. There is a very evident in- 

 crease in the number of spines with the age. 



The extent of variation of the second and third 3'ear specimens is the same. 

 The first year specimens, although only half as many, exceed the other ages two 

 rays in the extent of variation. 



TABLE IX. 



First 

 Year. 



Second 

 Year. 



Third 

 Year. 



Per cent, of specimens having 7 anal rays , 

 Per cent, of specimens having 8 anal rays 

 Per cent, of specimens having 9 anal rays 

 Per cent, of specimens having 10 anal rays 

 Per cent, of specimens having 11 anal rays 

 Per cent, of specimens having 12 anal says 

 Per cent, of specimens having 13 anal rays 



0.84 



5.09 



36.43 



51.69 



5.09 



0.84 



0.42 I 



1.69 j 0.82 

 32.19 i 20.57 

 52.53 61.60 

 13.12 20.16 

 ! 0.82 



