AMPHIPODA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 505 
The very large eye (red in colour, at least sometimes) found in some of the forms 
is certainly a very striking characteristic, and if it were constantly associated with other 
characters or with certain localities it would be entitled to great weight; but some 
specimens have the large eye associated with side plates which are not acutely produced 
anteriorly, while in the Kerguelen specimen the eye is large (black in this case) and the 
side plates are acutely produced ; again, both the large-eyed and the small-eyed forms 
are found together in Port Jackson. It is just possible that the large eye is a sexual 
character, or it may be developed in older specimens which live at moderate depths, as 
appears to be the case in Husirus antarcticus. 
I have thus failed to find the characters relied upon for specific distinction in this 
genus constantly associated in any definite way, and am forced to conclude that all the 
forms belong to one species widely spread in southern seas and found also in the North 
Atlantic and in the Indian Ocean. 
In addition to the localities mentioned above, the species P. antarctica has more 
recently been recorded from Ceylon by Mr Watxker, so that the conclusion that we are 
dealing with one species only, first arrived at on morphological grounds, is now con- 
firmed by the geographical distribution of the species. 
After the discussion as given above had been written, | was able to visit the British 
Museum and examine there the types of the different species; Mr WALKER also 
kindly sent me a specimen of P. atolli, and in doing so said that he now considered it 
probably not distinct from P. antarctica. I was able at the Museum to examine the 
type slides of Tritxta kerguelent Stebbing and of P. atolli Walker, and also to 
examine named specimens of P. osborna Calman, P. antarctica from the Discovery 
Expedition, and of P. antarctica recorded from Ceylon by Mr Watxer. The slide of 
the dissected parts of the Challenger specimen of Tritzta kerguelens is not in very good 
condition, but it is evidently the one from which Mr Sressrne’s excellent figures were 
made, and these are sufficient for our present purpose. 
The type specimen of P. atoll: has the first maxilla with short spinules on the palp 
as described, and the maxillipeds also correspond closely to the figure given, but in all 
other essentials it agrees with my Saldanha Bay specimen, both gnathopods closely 
agreeing, except that in the first the flange on the propod has the margin minutely 
serrate ; the first and second pereeopoda, again, have side plates similar to those in the 
Saldanha Bay specimen. An examination of P. osborni showed that this species also 
was the same as the Saldanha Bay specimen, and therefore the same as P. atoll. The 
side plate of the first gnathopod is produced in front a little more acutely than in the 
type of P. atolli, and is tipped with two small sete; the side plate of the second 
gnathopod is also produced in front, but not so acutely as the first, and might be 
described as being narrowly rounded anteriorly ; that of the first pereeopod is acutely 
produced, while the second is rounded as described by Catman. The eye is large. 
The Discovery specimens labelled P. antarctica undoubtedly agree specifically 
with SresBine’s type of Tritxta kerguelent in having the side plates all more or less . 
