8 
AUSTRALASIAN ANTARCTIC EXPEDITION. 
region, it is possible that this resemblance may have some significance. It is obviously 
undesirable, however, to attempt any large deductions from the more or less trivial 
indications of relationship between individual species in a genus so large and so widely 
distributed as Diastylis; and it is doubly undesirable in the case of inconspicuous 
organisms that have been so little collected, except in European seas, as have the 
Cumacea. 
Diastylis Helleri Zimmer. 
(Plate XX.) 
D. helleri, Zimmer, Zool. Anz. XXXI, 1907, p. 221; id. Wiss. Ergeb. Schwed. Siidpolar 
Exped. VI, Lief. 3, 1909, p. 15, pi. vi, figs. 84-96; Caiman, Deuxieme Exped. 
Antarct. Frai^aise, Cumaces, 1917, p. 1. 
Holostylis Helleri, Stebbing, Das Tierreich, Cumacea, 1913, p. 140. 
Occurrence .— Stat. II. 1 9 (immature). 
Remarks. The single specimen (which is much damaged) differs considerably 
in appearance from Zimmer’s description and figures, and from a syntype of his species 
in the Museum collection. It might indeed have been regarded, without much hesitation, 
as representing a distinct species characterised by the nodular excrescences on the 
carapace, were it not that certain specimens obtained on the voyage of the “ Nimrod ” 
and presented to the Museum by Sir Ernest Shackleton stand almost exactly midway, 
in respect of this character, between Sir Douglas Mawson’s specimen and those described 
by Zimmer. The “ Nimrod ” specimens differ from that now recorded in having the 
surface of the carapace much more spinous, but on the other hand they agree with it 
and differ from Zimmer’s syntype in having the pseudorostrum longer than the antennule, 
and the basal portion of the telson somewhat longer relatively to the post-anal portion. 
The single specimen which I have recorded from the second French Antarctic 
Expedition * is not now at hand for comparison, but according to my notes it agreed 
very closely with the “ Nimrod ” specimens. 
In describing this species, Zimmer called attention to its resemblance to the 
Arctic D. spinulosa Heller. It is, therefore, of special interest to find it presenting 
a series of variations parallel to those that, according to Hansen, link D. sjpinulosa with 
D. nodosa Bars. 
Stebbing has removed this species to a new genus, Holostylis, which he makes 
the type of a new family Holostylidse, having as its sole distinguishing character the 
unsegmented endopod of the uropods. 
Distribution. —South Georgia, 12-75 metres (Swedish S. Pole Exp.). Lat. 64° 49' 
35" S., Long. 63° 29' 4" W.; 70 metres (“ Pourquoi Pas?”). Cape Royds, 7-50 
fathoms (“ Nimrod ”). 
* The text of my note on this species in the Report of the French Expedition has apparently suffered from some 
accident now inexplicable. I must disclaim responsibility for the statement that Dr. Zimmer himself collected the species 
at South Georgia and the implication that he described the specimens obtained by the “ Nimrcd.” 
