DEVELOPMENT OF EUPHAUSIA SUPERB A 19 



FIRST NAUPLIUS 



As shown in Table IV there are only two records of free-swimming ist Nauplii in the 

 material examined, but at some of the stations where eggs were found, notably at 

 St. 537, many of the eggs contained well-developed naupliar forms. A Nauplius 

 measuring 0-62 mm. in length (Fig. i a) was dissected from an egg, the interior of which 

 it completely occupied. This differs somewhat from Ruud's description (1932, pp. 47, 

 49, fig. 11), in which the Nauplius in the egg is stated to be 0-51 mm. long and does not 

 completely occupy the space within the egg-shell. 



Q b 



Fig. I. First Nauplius ( x 46). a, specimen dissected from egg; b, free-swimming specimen. 



Table IV. Occurrence of First Nauplius 



Of the two free-swimming larvae one measured 0-63 and the other o-66 mm. They 

 were presumed to be E. superba from their relatively large size compared with other 

 Nauplii in the plankton, from their similarity to nearly hatched Nauplii dissected from 

 eggs of E. superba, and from their occurrence at stations containing recognizable eggs of 

 this species. 



The body of the Nauplius is in dorsal aspect oval in shape, broader posteriorly than 

 anteriorly (Fig. i b). It is in form a normal ist Nauplius with three pairs of swimming 

 appendages. The first pair of limbs is uniramous with the two succeeding pairs biramous. 



SECOND NAUPLIUS 



All the 2nd Nauplii occurred at stations where eggs were present ; because of this, but 

 particularly on account of their large size, they were assumed to be E. superba. The 

 average length of the 2nd Nauplius is 0-67 mm. with a range of from 0-63 to 0-70 mm. 



3-2 



