AMPHIPODA. 
15 
taken either by the ‘Discovery’ or ‘Southern Cross’ north of lat. 77° 50'. Male 
specimens with the lower an tennse developed in the manner supposed to indicate sexual 
maturity are very scarce, yet in a gathering from Castle Rock Seal Hole, W.Q., 
14^ fm. (no date), there are a number which, though only 15 mm. long, have the 
flagella with 36 joints well furnished with calceoli; and from Hole G, W.Q., 
23 Feb., 1903, 130 fm. (153), there is a probably adult male of 25 mm., which appears 
to be the maximum size. There is some variability in the form of the third pleon 
segment, the hinder angle of which is less rounded in some specimens, especially the 
largest, than in others. Mr. Hodo-son writes as follows :— 
“ This species was not regarded with favour when we were in Winter Quarters, 
and it is a matter of considerable regret that its seasonal development was not looked 
for ; its migration it was impossible to follow. It occurred first in considerable numbers 
on the 17th May, 1902, when the winter was well advanced. On that occasion the trap 
was hauled from 56 fathoms about 4.0 p.m. and then it was so dark that I was obliged to 
return to the ship for a lantern. The trap contained about 10,000 of these amphipods. 
A thousand individuals were counted, the volume ascertained, and this formed the basis 
for the present estimate of number and for future occasions. Four fish were in the 
trap, one of them had been reduced to an absolute skeleton ; on another the amphipods 
hung by their ‘ teeth ’ in a compact mass, completely concealing their victim. Its skin 
had disappeared, and I judged also about a millimetre of flesh, but the animal was still 
alive; the other two fish were presumably waiting their turn. 
“ From that date until 25th October, 1902, this species was taken generally in numbers 
varying between 10,000 and 30,000 at a haul, and this at all depths to 125 fm., which 
was our practical limit for ordinary work. Two or three times a trap was used in 173 
fm., in July and August 1902, but not many amphipods were obtained—100 or so at a 
time. These animals swarmed over the bait to such an extent as to make it obvious 
they kept other animals away ; otherwise the number of other animals captured was 
unaccountably small. Under these circumstances the presence of this amphipod was 
regarded as a nuisance, and as a large stock had been preserved, further captures were 
generally left on the ice at the mouth of the hole. My experience at the holes soon 
made it perfectly clear that there was no small mortality among the seals through their 
not being able to get to a breathing-hole in time during their wanderings, and thus 
affording a substantial food supply for predaceous Crustacea. I came to the conclusion 
that these amphipods travel about the sea bottom in vast hordes in search of food, a 
conclusion further accentuated by the fact that from 25th October to 27th December, 
1902, they completely disappeared from all the traps; stationary traps were not used 
during the same period of 1903. From October to January is the seals’ breeding season, 
and at this time they remain, for the most part, close inshore. The place nearest the 
ship where they congregated most was among the pressure ridges at Pram Point. 
These ridges are formed by the ‘ Barrier ’ ice intruding into the Sound between White 
Island and Cape Mackay and pressing against the land at Pram Point. As the ice did 
LS 
VOL. III. 
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