230 PROFESSOR CHARLES CHILTON ON THE 



Bay agree almost exactly with Plymouth males of the first form. 1 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 foims labelled 

 Podocerus iiigens 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," o,nd 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. PFEFFER'S type of Podocerus 

 ingens, 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 secondarv 

 teeth on the outer branch. In all the specimens that I have been able to examine I 

 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 WALKER. 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 valid us 

 Dana in New Zealand, and it has been described from Australia by Professor HASWELL 

 under the name Podocerus australis. In his report on the Challenger Amphipoda 

 Mr STEERING recorded it from Kerguelen Island under the name Podocerus falcata, 



(ROY. SOC. EDIN. TRANS., VOL. XLVIII., 512.) 



