512 PROFESSOR CHARLES CHILTON ON THE 
Bay agree almost exactly with Plymouth males of the first form. I have been able to 
compare my specimens with specimens of both forms determined by Mrs Sexton, and 
she has been good enough to examine them along with me, and agrees that the South 
Orkneys specimens are not sufficiently distinct to be looked upon as a separate species. 
I have also been able to compare my specimens with numerous forms labelled 
Podocerus ingens Pfeffer, from South Georgia, kindly sent to me by the authorities of 
the Hamburg Museum. Most of these appear to belong to the “first form,” and agree 
closely with Plymouth specimens ; they differ a little in the shape of the side plate of 
the second gnathopod, but the difference is slight, and there is a gap between this and 
the preceding side plate as described by Mrs Sexton. The second gnathopod itself 
agrees almost precisely with Plymouth specimens, both in the fully mature form and 
in the immature stages. In the flagellum of the lower antenna the joints are usually 
a little more distinct than in typical Plymouth specimens, but in the South Georgia 
specimens there is some variation in this point; apparently the joints are more distinct 
in younger forms and become more fully coalesced in the older ones; they bear the 
characteristic plumose hairs as described by Mrs Sexton. Prerrer’s type of Podocerus 
engens, which I have also been able to examine, is a very large specimen, 26 mm. in 
length. ‘Though apparently belonging to the first form, it differs a little in the shape 
of the second gnathopod; the thumb is comparatively small, and at its base on the 
outer side there is a small secondary notch or tooth that does not seem to be repre- 
sented in the smaller specimens labelled Podocerus ingens. It is possible that this 
large form may be a separate species, but I am inclined to think that it is only a very 
large form of Jassa falcata, and that the differences are merely those that we might 
expect to meet in such a very large form. Jassa goniamera Walker seems certainly 
to belong to J. falcata; the specimen he described and figured under this name is an 
immature male of the first form. He states that the third uropod bears no secondary 
teeth on the outer branch. In all the specimens that I have been able to examine | 
have found teeth present, as in the Plymouth specimens, though small; occasionally 
these may become lost in preserved specimens, and I presume that is what has 
happened in the specimens examined by Mr Watker. Jassa wandeli Chevreux, 
again, appears undoubtedly to be another specimen of the same species; his figure 54 
is taken from a male not quite fully mature, and shows the characteristic gap between 
the first and second side plates, while the lower antenna exactly corresponds, both in 
his figure and description, to that of the first form of the male. In the specimen 
he figures, the various joints of the flagellum appear to be slightly more completely 
coalesced than they are in some of the South Georgia and South Orkneys specimens, 
and thus more like Plymouth specimens of this form. 
I have long been familiar with this species under the name of Podocerus validus 
Dana in New Zealand, and it has been described from Australia by Professor Hasw#1 
under the name Podocerus australis. In his report on the Challenger’ Amphipoda 
Mr Srespine recorded it from Kerguelen Island under the name Podocerus falcata, 
