AMPHIPODA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 503 
Polycheria antarctica Stebbing, 1906, p. 520. 
i . Walker, 1907, p. 34. 
Tritezta osbornt Calman, 1898, p. 268, pl. xxxii. fig. 2, and p. 288. 
Polycheria atolli Walker, 1905, p. 926, pl. lxxxviii. figs. 1-5. 
Entrance to Saldanha Bay, Station 483. One specimen, 6 mm. long. 
South Orkneys, Scotia Bay, Station 325. Many specimens, all of small size, 
averaging 2 mm. in length. 
The specimen from Saldanha Bay is, I think, specifically identical with the 
Challenger form described under the name Tritzta kergueleni. The eye is very large, 
occupying the greater part of the side of the head; the posterior angle of the third 
pleon segment is quadrate, with a very short tooth, and the pleon and urus have the 
earination described, though to a less degree ; the antenne agree with the description 
as regards the proportions of the joints, the lower being a little longer than the upper ; 
the branches of the third uropods are slightly unequal. 
In the large eye and in other essential points it also agrees with P. tenwepes Has- 
well, and with P. obtusa G. M. Thomson, whose description of the terminal joints of 
the perzeopoda applies exactly to the specimen under consideration. In describing 
his specimen Mr Tuomson pointed out that it was probably the same as P. tenwipes 
Haswell. On the other hand, the Saldanha Bay specimen differs from the Kerguelen 
Island one in the side plates, which are not so acutely produced anteriorly. 
The specimens from South Orkneys are all small. The eye is of much smaller size, 
and the carination of the pleon is absent altogether or only slightly marked ; the joints 
in the flagella of the antenne are fewer in number, and the two antenne are about 
equal in length ; the outer branch of the third uropod is only about half the length of 
the inner; both the third and the fourth side plates are produced anteriorly into 
an acute lobe exactly like that figured by Sreppine for P. antarctica (1906, p. 520, 
fig. 91). In this respect, therefore, they differ from his description of P. tenuipes, with 
which they agree in some of the other points mentioned, for that species is described 
in Das Tierreich Amphipoda as having the fourth side plate reduced to a short, blunt 
lobe, this character being apparently taken from Catman’s description of P. osborni, 
which STEBBING gives as a synonym of P. tenwipes. 
These South Orkneys specimens are apparently immature, although the characteristic 
form of the terminal joints of the pereeopoda and of the third and fourth side plates is 
already present, and I think there can be no doubt they belong to the same species as 
the Saldanha Bay specimen. In the smaller eye they resemble P. brevicornis Haswell, 
which does not seem to be separated from P. tenwipes by any other character of 
importance. Mr WALKER (1907, p. 34) has pointed out that HasweE.w’s description of 
the second gnathopod of P. tenuipes and of P. brevicornis, and his figure of that of the 
first species, are quite unlike those of P. antarctica. The figure is undoubtedly very 
rough and insufficient, but the descriptions, so far as they go, are not inconsistent with _ 
TRANS. ROY. SOC. EDIN., VOL. XLVIII, PART II. (NO. 28). 75 
