DEVELOPMENT OF EUPHAUSIA SUPERB A 49 



If the larvae are arranged in two groups according to their average development as 

 expressed by their correspondence to the scale provided by the nine larvae mentioned 

 above, the result (Table XIX) is two sets of figures which correspond in their rano-e 

 with those of the larvae which are to be seven-spined or five-spined respectively in the 

 following stage. This is shown graphically in Fig. 11, 



Table XIX. Larvae with seven-spined telson from St. 374 arranged in 

 length groups according to their degree of development 



Attention is drawn here to Table XV for specimens from St. 639 in which the average 

 size of the larvae is much less than at St. 374. The larvae compare with the group of 

 larvae of small size at St. 374, and with the exception of two they can, like these latter, 

 be included in the range of development a to d. 



From these analyses, therefore, it is possible to reach the conclusion that in the develop- 

 ment of Eiiphaiisia superba the larvae possessing five pairs of setose pleopods and seven 

 terminal spines can be divided into two groups: {A) those having a succeeding seven- 

 spined stage and {B) those having a succeeding five-spined stage. 



The larvae may be identified as follows : 



Form A 



Smaller average size. 



Antennular flagellum usually shorter than the two 

 distal segments of the antennule. 



Mandibular palp sausage-shaped, not generally 

 multiarticulate. 



Endopod of ist thoracic limb not developed as a 

 swimming foot, about twice as long as exopod. 



Telson not having innermost postero-lateral spine 

 greatly modified. 



Telson length not fully three times the width. 



Form B 

 Larger average size. 

 Antennular flagellum usually longer. 



Mandibular palp distinctly three-segmented and 

 with terminal spine developed. 



Endopod of ist thoracic limb five-segmented, 

 much more than twice as long as exopod. 



Telson with proximal portion of the postero- 

 lateral spine widened greatly in comparison with 

 the distal portion. 



Telson length more than three times the width. 



LATER FURCILIA STAGES 

 For the development of the larvae after they have the full complement of setose 

 pleopods and less than seven terminal spines on the telson, a random sample of 243 

 larvae from St. 374 was examined. 



