DEVELOPMENT OF EUPHAUSIA SUPERB A 6i 



In the inner ramus the unsegmented condition is seen in Fig. 13 a. In Fig. 13 b this 

 has become divided into two. In Fig. 13 c the ramus is still divided into two, but of 

 these the proximal shows a foreshadowing of the two-segmented peduncle of later stages 

 while the distal segment is still unjointed. From this and from the examination of other 

 larvae at this station it is evident that the proximal segment divides into two, forming 

 the peduncle, before segmentation begins in the distal segment. In Fig. 13 d the ped- 

 uncle is distinctly segmented into two and the flagellar portion into four. Within the 



Table XXII. Length frequency of larvae from St. 374 arranged according to 

 the number of telson spines in the following stage 



integument the state of the flagellum in the following stage can be discerned as having 

 a much greater number of segments. 



Rustad (1930, p. 72) describes two different forms of development of the inner ramus 

 of the antenna in euphausians. In the one (Fig. 14 b) the flagellum and peduncle are 

 already separated in the two-segmented stage — the E. frigida type. In the other (Fig. 

 14 a) the peduncle and flagellum part in the three-segmented stage — the Thysanoessa 

 macnira type. Euphaiisia siiperba (Fig. 14 c) follows the E. frigida type but differs from 

 it in that the peduncle divides again into two before segmentation of the flagellum 



