SAGITTA GAZELLAE 255 



Marr referred to the races as Large Southern (L.S.), the Antarctic form, and Small Northern (S.N.) 

 the Subantarctic form. I have also followed this practice. 



Table 10 a, b shows Marr's data from two hauls, one Antarctic, and the other Subantarctic, in 

 which the stages of maturity and total lengths are compared. It is evident that there can be no 

 confusion between the two races when the gonads are visible. In the Subantarctic race Marr's stage 1 

 begins at about 25 mm. total length, and it is only in specimens smaller than this that the gonads are 

 not visible; thus below 25 mm. it is not possible to determine the race by the method just described. 



1 2-3 4 



Fig. 14. Stages of maturity devised by J. W. S. Marr for differentiating the races of S. gazellae. The upper series show the 

 stages of the testes and the lower series the stages of the ovaries. No ovaries have been drawn in the upper series, and no testes 

 in the lower series, as no particular stage of maturity of the testes is necessarily combined with a particular stage of maturity of 

 the ovary. 



In practice this does not matter, as hauls are usually composed of one race or the other, and mixing 

 only takes place in a few areas. However, it is possible in most cases to differentiate the immature 

 forms by the number of hooks, although the method is not infallible, as there is slight overlap in the 

 hook numbers, but in general it is satisfactory. I have found the basic number of hooks in the S.N. 

 race to be 14 and in the L.S. race 12 (rarely 13). Comparison of Figs. 8 and 15 shows that below 

 25 mm. individuals of the L.S. race are likely to have 1 1 or 12 hooks, whereas individuals of the S.N. 

 race are likely to have 13 or 14. The overlap is evident, but not extensive. Counts of hook numbers 

 from individuals below 12 mm. are not reliable, as even with a high-power monocular it is difficult to 

 be certain of the numbers present. 



