DEVELOPMENT OF EUPHAUSIA SUPERBA 39 



last-mentioned genus Macdonald, as already stated, recognized eleven Furcilia, but of 

 these the Furcilia having three pairs of non-setose pleopods and that having three pairs 

 setose and two pairs non-setose are dominant. On analogy with what happens in 

 Eiiphansia siiperba, particularly with respect to the larvae from St. WS 527, I think it 

 reasonable to suggest that these two " dominant " forms are in fact the first two Furcilia 

 stages, that stages identified by having no pleopods, one pair, two pairs and three pairs 

 of simple pleopods are variants of the early stage and that the remainder with setose 

 pleopods are variants of the 2nd stage. 



Table XII. Frequency of occurrence of larvae of varying form at 

 stations where representative samples were taken 



The institution by the early writers of a succession of Furcilia stages, recognized by 

 the addition of pleopods commencing with the pair on the first abdominal segment 

 and later by the provision of setae on these pleopods, is apparently based neither on 

 direct evidence of moulting nor (until Macdonald 's work on Meganyctiphanes) on any 

 quantitative analysis of the material. The result of Macdonald's quantitative investi- 

 gation has already been stated, and his observations of moulting show that more than 

 half do so "irregularly"; of the remainder which moult "regularly" he does not 



