504 PROFESSOR CHARLES CHILTON ON THE 
either the Saldanha Bay or the South Orkneys specimens before me, and these, as | 
have said, must, [ think, be referred to P. antarctica. 
STEBBING, in 1906, made P. osborna Calman a synonym of P. tenuipes Haswell, to 
which he also assigned P. obtusa G. M. Thomson and, with a “?”, P. brevicornis 
Haswell. 
In describing P. osborni, CALMAN referred to the southern species described, and 
said they ‘“‘are probably all referable to one.” If this is done, however, it will then 
certainly be impossible to retain his species as distinct. This will be seen if we take 
the points of difference in order :— 
1. Dorsal processes of urus much less prominent. This applies also to the South 
Orkneys specimens, and, to a less degree, to the Saldanha Bay specimen. 
2. Maxillipeds with outer plates nearly equalling the palp in length and bearing 
only about eleven spines. In the South Orkneys specimens the plates bear only 
eleven spines, though they are rather shorter than the palp. In P. atolli, too, WALKER 
describes the spines on the outer plate as few in number and present on the distal 
portion of the margin only. 
3. Propod of first gnathopod with palmar edge short and not more than one-third 
the length of the dactyl. In the Saldanha Bay specimen the gnathopod agrees well 
with CaLMAN’s description, except that the palm is perhaps a little longer. From the 
appearance of this specimen, however, I think the palm is really longer than is shown 
in Catman’s figure, and that the lobe against which the dactyl is represented as 
impinging is overlapped by the dactyl folding in on one side of it. If this is so, there 
is no essential difference between the palm of P. osborni and that of P. antarctica 
as figured by SreBBine under the name P. kerqueleni. 
CaLMman’s description of the second gnathopod agrees quite well with that of the 
Saldanha Bay specimen. 
4. Fourth side plate having the anterior process reduced to a short, blunt Jobe. 
This applies also to the Saldanha Bay specimen and to P. atoll1 Walker. 
5. Propod of third perzeopod not widening distally. Both the Saldanha Bay and 
the South Orkneys specimens agree in this point with Cauman’s figure rather than with 
STEBBING’S; the difference is one of degree only, and the widening is probably more 
marked in older specimens. 
In view of all the considerations mentioned above, I feel compelled to unite also 
P. atolla Walker, from the Male Atoll, Maldive Archipelago, with P. antarctica. 
His description of the gnathopoda and of the first and second pereeopoda, and of the 
side plates corresponding to these appendages, applies very well indeed to the Saldanha 
Bay specimen and also fairly well to P. osborni; but in the fewer spines and teeth on 
the outer plate of the maxillipeds and on the uropoda, P. atolla agrees rather with the 
South Orkneys specimens. Its chief peculiarity seems to be the fact that the palp of 
the first maxilla has “the top squarely truncate and crowned with short teeth,’ but in 
view of the other characters this is hardly sufficient to maintain it as a separate species. 
a 
