52 JOHAN HJORT. M.-N. Kl. 



grown, and at every stage of development, as well as Evadne Nordmatini. 

 On the West Coast, of the Calanida, Calanus finmarchicus, Pseiido- 

 Calmius elongatus, and Paracalaniis parvus are the most common ; 

 whilst in the Christiania Fjord the vast majority consisted of Haliteniora 

 longicornis. The larva of Molluscs and Annelides appear, likewise, in 

 greater and lesser numbers, as well as Appendiculars Sagitta, the eggs 

 of fishes &c., &c. 



Of the one-celled organisms, Cilioflagellata is almost exclusively met 

 with, and of these, mainly, Ceratium tripos. The total absence o{ Dia- 

 tomaceœ, especially the species of Chœtoceros, is very characteristic. 



During the Autumn of i8gj, the Plankton differed to the greatest 

 extent from that of the Summer. It was found in great abundance in 

 the Norwegian Channel, consisting of both animal and plant life. Be- 

 sides the larvae of Bryozoa Bivalves, Echinoderms and Copepoda, as well 

 as various adult forms of Calanida, we find that Cilioflagellata (Cera- 

 tium tripos, fusus, furca) were present, and, above all, great quantities of 

 Diatomaceœ, of which chiefly Chcetoceros borealis, and curvisetus. These 

 last species were entirely absent during the Summer season. Up in 

 the Christiania Fjord the Plankton was peculiar to a degree. Of animal 

 Plankton only one rare Nauplius was found, whilst the very 

 abundant, slimy and bright green coloured Plankton consisted almost 

 entirely of Diatomaceœ, especially Chcetoceros curvisetus, and skele- 

 tonema costatum. (It will be remembered that, in hydrographical re- 

 spects, the Autumn of 1893 differed to a vast extent from the Summer. 

 See, moreover, what follows below.) In the Hardanger Fjord during the 

 same Autumn, the Plankton was, on the other hand, sparse and con- 

 sisted for the most part of Cilioflagellata, but some few Diaiomacece 

 were also obtained there. 



The Autumn of 1894, was again very different to that of 1893. As 

 in November 1 893, only forms of larvæ w'ere found in great numbers, 

 but otherwise the Plankton was sparse. That which was characteristic 

 above all, was the predominant occurence of Cilioflagillata especially 

 Ceratium tripos, whilst the Diatomaceœ, which, in the previous year 

 were present in such vast numbers, were almost entirely absent on the 

 surface both on the West Coast as well as in the Christiania Fjord. The 

 conditions in the deep proved to be otherwise. During the investigations 

 off Fredriksvaern on the 17th December 1894, samples were also taken 

 vertically, from a depth of about 50 fathoms and upwards, at the stations 

 Nos. 1 16 and 1 14 (See PI. V, Fig. 5}. At these trials the Plankton proved 

 to be abundant, especially at .station 114, and, besides the surface Plankton, 



