W. JI. TATTERSALL. 



maturity concern chieHv the rostrum and tlie antennules, and these notes refer to these 

 organs more particularly. 



The smallest recognisable specimen of E. superba measured 12' 5 mm. in length. 

 The anterior end is represented in Plate I., Fig. 4. The rostrum is a bluntly rounded 

 triangular plate. The spine on the outer distal corner of the basal joint of the 

 antennule is still larval in character, being much longer than in larger specimens. 

 There is no trace of the lobe from the basal joint of the autennule, but the one from 

 the second joint already shows as a slight membranous projection of the anterior 

 margin. The antenual scale also shows larval characters in that the outer margin 

 is shorter than the inner. Finally, the telson has assumed adult form, but the dorsal 

 spiuules immediately anterior to the sub-apical spines are still long and plumose. The 

 lateral spine of the carapace is present, but small. Between 12 '5 mm. and 15 mm. 

 the spine on the basal joint of the antenuule gradually shortens up and assumes the 

 characters seen throughout adult life. The antenna! scale also assumes adult form, 

 and the spinules immediately anterior to the sub-apical spines on the telson lose their 

 plumose character and shorten to adult size. The rostrum, however, still remains 

 obtusely rounded. 



The next stage is that described by Sars as E. antarctica, and measures 17 mm. 

 The rostrum has now become a broad, acutely pointed triangular plate, while the lobe 

 from the basal joint of the anteunules first becomes evident as a slight inflation of the 

 anterior margin. This is shown by Sars in his ' Challenger ' Report (Plate XV., 

 Fig. 2). He has, however, overlooked the lobe on the second joint of the anteunules, 

 which is now considerably forward in development. The spine on the lateral edge of 

 the carapace is now quite conspicuous. 



Sars describes E. Antarctica as being without lateral denticles. Examination of 

 his type specimen, however, shows that, while the side from which he took his 

 figure is rather damaged and the spine not visible, on the other side the 

 spine is quite conspicuous and perfect. This removes the only serious difference 

 which existed between the young E. superba here noted and Sars' description of 

 E. antarctica. 



The transition from E. antarctica at 17 mm. to E. glacialis, Hodgson, is simple 

 and obvious. I figure (Plate I., Fig. 3) the anterior end of a typical glacialis stage 

 from a specimen 26 mm. in length. The only differences to be noted from the 

 antarctica stage are the better development of the antenuular lobes and the shortening 

 and broadening of the rostrum, which is still, however, pointed at the apex. The stage 

 figured agrees well with Hodgson's figures and description of E. glacialis. 



After a length of about 27 mm. the sides of the rostrum gradually become more 

 and more concave till at about 30 mm. the completely adult form is reached. Very 

 little change takes place in either the form of the rostrum or the antennular lobes after 

 a length of 35 mm. has been attained, except, of course, in the changes accompanying 

 the last two or three moults in the male, already noted above. Examination of the 



