150 



lamellar projection, terminal joint of same leg securiform, that of left leg com- 

 paratively broad. 



Colour. Body in both sexes highly pellucid, with a very faint tinge 

 of blue. Length of adult female reaching to 1.25 mm., of male to 1.05 mm. 



Remarks. This form was first described by Prof. Lilljeborg in his well- 

 known treatise on the Entomostraca of Skane under the name of Diax lo))<jir<'>ni*. 

 It is not easy at once to distinguish this form from some of the other species, 

 to which it bears a great similarity. On a closer examination, however, it may 

 be readily recognized in both sexes by the slender and delicate spinule occurring 

 on the dorsal face of the lateral lobes of the last segment of the metasome, as 

 also by the relative length of the anterior antennae and caudal rami. More- 

 over the apical spine of the outer ramus in the 2nd to 4th pairs of legs is more 

 elongated than in most other species, and the difference in the last pair of legs 

 in the female is very distinctly marked by the slenderness of the terminal joint, 

 which is exserted to a very thin, flexible point, whereas in most other species 

 this joint is pronouncedly spiniform. 



Occurrence. This Calnnoid is distributed along the whole Norwegian coast, 

 from the Christiania Fjord to Vads0, sometimes occurring in great numbers. It 

 is a true pelagic form, being often met with far out at sea, and at the very 

 surface. Not unfrequently, however, it is brought by the current close to shore; 

 and it is even often found in tidal pools together with Paracalanus }>nrrn^ and 

 Temora longicornis. It moves with great rapidity in abrupt bounds. 



Distribution. British Isles (Brady), Kattegat (Lilljeborg), the Baltic (Gies- 

 brecht), Gulf of Finland (Nordqvist), Faroes Isles (Cleve), Iceland and southern 

 Greenland (idem), Spitsbergen, polar basin, north of the New iSiberian Islands 

 (the present author). 



63. Acartia Clausi, Giesbrecht. 



(PI. CI). 



Acartii Clamii, Giesbrecht, Fauna & Flora des Golfes von Neapel. Pelagisclie Copepoden, p. 507, 



PI. 30. figs. 2, 4, 1315, 17, 28, 36, 47; PI. 42, fig. 32; PI. 43. figs. 3, 5, 14. 



Syn: Dias longiremis, Claus (not Lilljeborg). 



Specific Characters. Female. Very like the preceding species both in 

 size and general appearance, and, like the latter, without any trace of tentacular 

 appendages in front. Lateral lobes of last segment of metasome, however, 

 without the dorsal spinule found in A. longiremis, but having the edge armed with 

 from 4 to 6 extremely small and closely set denticles. Urosome with the first 2 



