2o 4 DISCOVERY REPORTS 



was perhaps right in saying that a general habitus figure was not good enough to de- 

 termine a species in a group where so many species bear a close superficial likeness, one 

 might maintain that Pfeffer has figured the characteristic gnathopods rather well, yet 

 it is to be presumed that the specimens he examined were part of Pfeffer 's type material. 

 Therefore Chilton was justified when he presumed the identity of Stebbing's and 

 Pfeffer's species. I say presumed, because I am sure that if Chilton had really subjected 

 his material to a critical examination he would have noticed the distinctions between 

 the two forms. 



Secondly, as to the validity of Pfeffer's names. According to the Zoological Rules and 

 Opinions, a figure is good enough to determine a species, and in the case of monotypic 

 genera the species confirms the genus. Therefore both of Pfeffer's names are valid and 

 as they antedate Stebbing's names 1 we should have to suppress the latter even if the 

 conclusions set out below, as to serraticauda being a separate species, be not accepted. 



Moreover it rather seems as if Atyloides, proposed by Stebbing for specimens which 

 he referred to Paramoera australis, and to which he added two new species of his own, 

 should become a synonym of Paramoera rather than of Schraderia. But this is a minor 

 point, compared with the vindication of Pfeffer's names. 



Schraderia gracilis, Pfr. (Figs. 118 c, 123). 



Pfeffer, 1888, p. 141 and pi. ii, fig. 5 (habitus figure only). 



? Walker, 1903, p. 58, pi. xi, fig. 90 (serraticauda, non Stebb.). 



? Chilton, 1912, p. 497 (serraticauda, non Stebb.) and p. 497, pi. ii, figs. 21-23 (calceolata <$); 



1921, p. 224 (part). 



? Chevreux, 1906, p. 87; 1913, p. 179. 



? Schellenberg, 1929 a, p. 280 (Atyloides g.). 



? Barnard, 1930, p. 388 (P. serraticauda, non Stebb.). 



Occurrence: 1. St. 27. South Georgia. 2 $$ 8-9 mm., 1 $ 11 mm. 



2. St. 141. South Georgia. Many 6-16 mm., mostly ovig. $$ 10-16 mm. 



3. St. 144. South Georgia. 2 SS 8-1° mm., 1 ovig. ? 12 mm. 



4. St. 145. South Georgia. 40 $$, incl. ovig., n-i4mm. 



5. St. 159. South Georgia. 2 ?$ n-i2mm. 



6. St. WS 25. South Georgia. 1 ovig. ? 10 mm., 2 ovig. $? 13 mm. 



7. St. WS 56. South Georgia. 1 immat. ? 16 mm. 



8. St. MS 6. South Georgia. 7 $? (5 ovig.) 10-12 mm. 



9. St. MS 10. South Georgia. 1 immat. $ 11 mm. 

 10. St. MS 67. South Georgia. 1 ? 12-5 mm. 



Remarks. In the form known as serraticauda, auctorum, it has been alleged by 

 Walker, Chilton and Chevreux that considerable variation occurs in the number of 

 serrations on the postero-inferior margin of pleon segment 3 . This variation is said by 

 Chilton and more definitely by Chevreux (191 3) to vary according to the size of the 



1 Though the month of publication of the respective papers is not apparent, Stebbing (1888, vol. 11, 

 p. 1653) includes a precis of Pfeffer's paper, and on p. 1654 definitely states that Stebbingia, Pfr., would have 

 priority over Atyloides, Stebb., if the two were considered identical. This proves that Pfeffer's paper was 

 published before the Challenger Report. 



