MARINE CRUSTACEANS. 455 



specimen, however, in this collection, namely the largest, the surfaces of the three carinae 

 are nearly smooth ; with only a few scattered spinules. The intermediate marginal teeth 

 are much reduced and the lateral marginals obsolete ; the carinae of the 6th abdominal 

 segment are considerably swollen, with or without terminal spines. 



\^, length 15, 1 ?, 13, and three very small specimens, Hulule, Male Atoll; and 1 ?, 

 length 9, Goidu, Goifurfehendu Atoll. 



IV. Var. N. = espinosus Borradaile. 



Approaches nearest to var. tumidas, the three carinae being swollen as in that variety, 

 but considerably less so than in var. spinosus ; it resembles the latter in having the inter- 

 mediate marginal teeth much reduced and the lateral marginals obsolete. The carinae of 

 the submedian and intermediate teeth are sharply defined : the carinae of the 6th abdominal 

 segment somewhat swollen, only the laterals with spines. 



V. Var. 0. PI. XXIII. fig. 13. 



Resembles var. incipiens a, but has an extra low carina on the median side of the 

 intermediate marginal teeth. East-American. 



I have seen, of this variety, one dry specimen in the S. Kensington Museum, and two 

 spirit specimens in the Cambridge Museum ; and am permitted to figure one of the latter by 

 the kindness of Dr S. F. Harmer, F.R.S. In this figure it should be noticed that the median 

 carina ends in an ' anchor,' a little more complete, perhaps, than in var. incipiens a but 

 less complete than in var. incipiens b (compare figs. 10 — 11 with fig. 13, and these with 

 Dr de Man's Fig. 77). In the brief note in which Dr Hansen describes his G. oerstedii, 

 he lays stress only on the point in which his species differs from G. chiragra, namely the 

 extra carinae on the intermediate marginal teeth, so that he naturally does not state whether 

 the ' anchor ' is present or not. As this ' anchor ' may or may not be present in the eastern 

 varieties of G. chiragra, it no doubt might or might not be present in Hansen's western 

 form. Should Dr Hansen's original specimens be without the ' anchor,' then the name ' var. 

 oerstedii' must be applied to the anchorless forms, and these anchored forms must be given 

 a different name; but until this fact is definitely ascertained, I prefer not to name the 

 present form, but to letter it only, for I think it very likely that Dr Hansen's forms will 

 be found to present traces of the 'anchor.' These traces may vary considerably in the 

 degi-ee of their development, just as they do in var. incipiens, and in fact, in the second 

 of the two Cambridge specimens, though it is of the same size as the first, the 'anchor' 

 is so imperfect that its presence might be easily overlooked. (The two specimens are of 

 different sexes, but I have seen no evidence of sexual variation in this character in the 

 analogous var. incipiens or var. smitkii.) Moreover, in the specimen from South Kensington, 

 the anchor shows signs of separation from the median carina, though not to the same 

 degree as in var. segregatus ; the flukes, though quite separated from the median carina, 

 are only imperfectly separated from each other in the middle line. The median carina, in 

 this case, ends in a minute spine. In any case, the presence of the ' anchor ' here is 

 interesting as showing the very close affinities of the eastern and western forms, and if the 

 western also varies, like the eastern, in regard to the presence or absence of the anchor, 

 the evidence of relationship is still stronger. 



VI. Var. 0. ? = oerstedii Hansen. 



Similar to var. 0. but ? without any anchor to the median carina. East- American. 



