studies on mariiiu Oslracods 631 



gat) and the Antarctic were on an average somewhat smaller than the males. The shape differs 

 from that of the male especially by the posterior part of the shell being somewhat larger than 

 the anterior part. The spine on the postero-dorsal corner of the right valve is more powerfully 

 developed than in the male, about the same as in pi. XIII, fig. 19, G. W. MOller, 1906 a; in 

 the Antarctic females this process was as well developed as in the Arctic ones. In other respects 

 the shell resembles that of the male. 



First antenna: — The boundary between the first and second joints is weakly 

 developed. On the anterior side of the proximal third of the e-bristle there are rather sparse 

 short hairs. All the joints are bare. In the proximal part of this limb there are in most cases 

 rather abundant small yellowish-brown corpuscles (explained as eyes by some previous writers; 

 cf. p. 560 above). 



Second antenna: — The protopodite is only slightly smaller than in the 

 male. The proportion between the length of the protopodite and that of the exopodite 

 is about the same as in the male. Endopodite: This has two joints, the original second 

 and third joints being quite united. One of the c- and d-bristles is sometimes developed and is 

 in most cases somewhat shorter than the width of the second joint; it is bare or almost bare; 

 cf. my fig. 8; in most cases, however, both these bristles are absent. The g-bristle is about 

 a quarter or a third shorter than the protopodite, sometimes even still shorter; it is onlv slightlv 

 sword-shaped distallv and is furnished with sparse and extremely short and fine hairs. The f-, 

 h-, i- and j-bristles are of somewhat different lengths, about a quarter or a third shorter than the 

 g-bristle; they are bare. It is to be noted that in this sex the g-bristle is thus longer than the 

 f-bristle, contrary to what is the case in the males. The h-, i- and j-bristles have no distinct 

 shafts. Between the h- and i-bristles there is a short peg-like process. Pilosity: The second 

 endopodite joint is bare. 



Sixth limb: — The long-haired bristles of the endopodite and the first exopodite 

 joint are often somewhat shorter in comparison and more weakly developed than in my fig. 30 

 of C. symmetrica. The dorsal one of the three bristles on the end joint is about a third shorter 

 than the middle one; sometimes it is even stiU shorter; cf. the adjoining fig. 11. 



Rod-shaped organ: — This varies somewhat in type ; in most cases it is about 

 the same as in the adjoining fig. 13; cf. also G. W. MCllek, 1906 a, pi. XIII, fig. 23. The shaft 

 reaches to about the boundary between the second and third joints of the first antenna. The 

 capituluni, which points straight forward, is somewhat longer than in the male. 



Remarks: — It seems to be quite certain that the form dealt with by me above is identical Synonynu. 

 with C. elegatis, G. 0. Sars, 1865. The original description of this species is certainly very 

 incomplete and, if the material were caught in a region so rich in similar forms as, for instance, 

 the middle Atlantic, it would not have been adequate for a quite certain identification of the 

 species. The region in which G. 0. Sars caught the species in question — the coast of Norway — 

 is, however, very poor in Halocyprid species. Although the plankton fauna of this region has 

 been subjected to a rather intensive study, it has so far been found to comprise only three species 

 of this group, namely Conchoecia elegans, C. obtusata and C. horealis, which were all established 



