AMPHIPODA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 223 



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 Eusirus antarcticus. 



1 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 WALKER, 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, I 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 Tritseta kergueleni Stebbing and of P. atolli Walker, and also to 

 examine named specimens of P. osborni Caiman, P. antarctica from the Discovery 

 Expedition, and of P. antarctica recorded from Ceylon by Mr WALKER. The slide of 

 the dissected parts of the Challenger specimen of Tmtseta kergueleni is not in very good 

 condition, but it is evidently the one from which Mr STEBBING'S excellent figures were 

 made, and these are sufficient for our present purpose. 



The type specimen of P. atolli 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 perteopoda, again, have side plates similar to those in the 

 Saldanha Bay specimen. An examination of P. osbond showed that this species also 

 was the same as the Saldanha Bay specimen, and therefore the same as P. atolli. 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 setse ; 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 perseopod is acutely 

 produced, while the second is rounded as described by CALMAN. The eye is large. 



The Discovery specimens labelled P. antarctica undoubtedly agree specifically 

 with STEBBING'S type of Tritasta kergueleni in having the side plates all more or less 



(HOT. soc. EDIN. TRANS., VOL. XLVIII., 505.) 



