193 



Occurrence. I have met with this form occasionally in plankton both 

 of the west and south coasts of Norway, as also in the upper part of the 

 Christiania Fjord. Mr. Nordgaard has taken it in Oster Fjord, near Bergen. 



Distribution. Polar Sea, north of Siberia (Nansen's Expedition), British 

 Isles (Farran). 



104. Oncaea similis, G. O. Sars, n. sp. 

 (PI. CIX, fig. 1). 



Specific Characters. Female. General form of body very similar to 

 that in the preceding species, though perhaps a little more slender. Anterior 

 division narrow fusiform in outline, with the dorsal face quite evenly vaulted, 

 no trace being found of the dorsal hump present in the preceding species. 

 Tail about half the length of the anterior division, and having the genital 

 segment rather large, nearly twice as long as the remaining part of the tail; 

 the 2 succeeding segments very short, and combined scarcely longer than the 

 anal segment. Caudal rami about the length of that segment and agreeing 

 in form and armature with those in the preceding species. Antennae and oral 

 parts also very similar, except that the maxillary palp is of somewhat simpler 

 structure, being only provided with 5 marginal setae. Natatory legs on the 

 whole agreeing in structure with those in the said species, though having the 

 spines of the outer ramus comparatively stronger and more coarsely denticulated. 

 Last pair of legs with the free joint still smaller than in O. borealis; apical 

 setae, however well developed. 



Colour not yet ascertained. 



Length of adult female 0.78 mm. 



Male unknown. 



Remarks. The present form is closely allied to O. borealis, and may 

 indeed at the first sight be easily confounded with it. On a closer inspection 

 it is however at once distinguished by the absolute absence of the characteristic 

 dorsal hump, as also by the rather different mutual relation of the caudal 

 segments. 



Occurrence. A few female specimens of this form were found together 

 with O. borealis in a plankton-sample taken by Mr. Nordgaard in the Oster 

 Fjord, near Bergen, and kindly sent to me for examination. 



