2S 6 DISCOVERY REPORTS 



Figs. 8 and 15 also show that the L.S. race is, in its hook numbers, intermediate between S. lyra 

 "gazellae "-type and the S.N. race. This is an interesting point, as it shows that the tendency in 

 S. gazellae is to have less hooks in cold water than in warm, whereas the cold water form of S. lyra 

 (S. lyra "gazellae "-type) has more hooks than the warm water S. lyra " lyra "-type. That the L.S. race is 



Table 10 a. ' Small Northern ' form of Sagitta gazellae 



(Stages distinguished by J. W. S. Marr.) 

 Station 839 



* Rudimentary vesicles. 



Table 10b. 'Large Southern' form of Sagitta gazellae 



(Stages distinguished by J. W. S. Marr.) 

 Station 825 



in this way apparently an intermediate form between S. lyra and S. gazellae is of no practical taxonomic 

 significance, for the L.S. race seldom extends more than a hundred miles or so north of the Antarctic 

 Convergence, and so could never be found mixed with S. lyra : indeed the whole Subantarctic area 

 separates the two forms 



Another feature in which the L.S. race resembles S. lyra is the occasional retention of posterior teeth 

 at stage III and IV maturity. The total loss of posterior teeth is an almost invariable feature of the 



