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3 

 C 



FISHERY BULLETIN; VOL. 74, NO. 2 



27 



25 



20 



15- 



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10 



-! \ r- 



I 12 13 14 



LAYERS (number) 



15 



T 

 16 



17 



OCCLUDED 



Figure 32. — Scatterplot of number of corpora on number of postnatal dentinal layers in Stenella attenuata. Circled s3rmbols are 

 senile females [shriveled oveiries with no corpus luteum or Type 1 or 2 corpora albicantia]. 



apparently nonreproductive ovarian events that 

 resulted in corpora belonging to all of the t5^es 

 through which a corpus luteum must pass during 

 regression to a small corpus albicans. 



Calculation of average ovulation rates from the 

 data in Figure 32 must take into account indi- 

 vidual variation in age at first ovulation. The fe- 

 males in Figure 32 were grouped into 10 one- 

 layer intervals beginning with 7.5 layers (Table 6). 

 The average reproductive age in interval p was 

 calculated as 



A = [ 2 a,&< J ^ c, 



where a, = % maturing in iih. interval (% mature 

 in i minus % mature in i - 1) 

 b, = average reproductive age in interval 



p of females mature in i 

 c = % mature in interval p. 



Average reproductive age in the ith interval of 



260 



