436 



DEPARTMENT OF TEE NAVAL SERVICE 



Tropical Water. ("Acadia" Station 41.) 



Length (mm.). 



Tail percentages. 



30 



28 

 30 

 30 

 32 



29 



The range in percentage is the same for the two types (32-23), but for any given 

 length it is very different, for example, for 12mm., 23-24 per cent and 27-29 per cent. 

 If we consider 20mm. the ordinary upper limit for the boreal water and 12mm. that 

 for the tropical water, we find that for corresponding sizes the percentages are as 

 nearly the same as could be expected. Half-grown individuals show percentages of 

 30 and 27-29, respectively; two-thirds grown individuals of 26-28 and 25-28; fully- 

 grown individuals of 23-24 and 23. , , • n i- 



It is probable that we have not to do with two races, but that the tropical lorm 

 is constantly brought to the boreal water, keeping the strain uniform. The differences 

 may be confidently be referred purely to the environmental factors. Cold may be said 

 in this species to increase the length, delay maturity till a much greater length is 

 attained delay the decrease in tail percentage correlative to maturity, and increase 

 the number of jaws. We have the number of jaws correlated with size and the tail 

 percentage corrleated with maturity (attainment of maximum size and also maturity 

 of sexual organs). 



DISTRIBUTION. 

 "Acadia." 



■ tation No. 



12 



Hour. 



3 a.m 



6 a.m 

 6 a.m 



9 a.m 

 3 p.m 



Depth 

 (metres). 



45 



over 2,000 



over 2,000 

 over 2,000 



Depth of Haul (metres). 



60- (V.). 

 (T.). 



40- (V.). 



(T.). 



100- (V.). 



(T.). 



70- (V.). 



200- (V.). 



Length (mm.). 



19 

 10-15 

 15-20 

 14 

 13 

 13-15 

 16-17 



(T.). 



14 

 14-15 

 16-24 



^Number. 



1 

 35 

 43 



3 



2 

 3-MXlO 

 3 

 

 1 

 3 

 18+1X10 

 



