SCHIZOPODA. 
7 
(2) In E. superba the rostrum is shorter ancl blunter than in E. murrayi, and has 
the margins less deeply concave. This, again, is clearly shown to be a sexual 
difference in PL I., Figs. 1 and 2. The rostrum of the male figured (Fig. 2) is shorter 
than that of the female, but is still rather more acute than in Sars’ figure of E. superba. 
Reduction is probably not complete till a size of at least 48 mm. is attained. 
A further difference between the two sexes is brought out by the figures here 
given, namely, the reduction in the male of the spine on the outer distal corner of the 
basal joint of the antennular peduncle. It is not visible in dorsal view, being hidden 
by the slightly projecting anterior margin of the joint, but it still persists as a small 
blunt protuberance. In the female, on the contrary, it is well-developed, distinctly 
visible in dorsal view, and acutely pointed throughout life. 
A fourth distinction shown in the figures, the absence in the female of the curved 
setae on the dorsal surface of the basal joint of the antennules, is due to the accident 
that in the female from which the figure was taken, these set® had become broken off. 
They are, in reality, present, and equally developed in both sexes. 
The above detailed description proves, I think, clearly, that E. superba and 
E. murrayi are the adult male and female, respectively, of one species which must bear 
the name E. superba Dana. 
I also give (Plate I., Figs. 5-9), figures of the mouth organs and endopods of the 
first two thoracic limbs, to show two characters in which E. superba differs from all 
other Euphausia yet described. The first of these points is the narrow and elongate 
form of the terminal joint of the mandibular palp, with its peculiar armature of four or 
five terminal strong plumose set®. In all the other species of the genus (with the 
exception of E. antarctica, Sars, and E. glacialis, Hodgson), the terminal joint of the 
mandibular palp is much shorter and stouter. In the two exceptions just mentioned 
the mandibular palp is figured by Sars and Hodgson respectively, almost exactly as 
here given for E. superba. This fact first suggested to me that these two species were 
only developmental stages of E. superba, a suggestion fully borne out by the evidence 
derived from a study of the present collection. The second distinctive character of the 
appendages is found in the great length of the set® arming the joints of the thoracic 
limbs. They are very much longer than in any other species of the genus, and with 
the character of the mandibular palp serve for recognition of E. superba at any stage 
in its development. 
Euphausia superba is the giant of the genus, and the only one of Dana’s original 
four species which is now retained by Hansen (1905 (2)), the other three having been 
cancelled by that author as unrecognisable. 
Some Notes on the development of E. superba. 
These notes were made chiefly with a view to confirming the suspicion, aroused 
by the similarity in mouth organs, that Euphausia antarctica and E. glacialis were 
merely developmental stages of E. superba. The changes which accompany growth to 
