15 



the south eastern parts of the North Sea, is a species with large 

 and heavy spores, Blddidphm mobiliensis. 



On the West Coast of Norway there are only some places 

 within the belt of islands, which are so shallow as to allow of 

 their favouring the growth of a Neritic Flora. Outside it there 

 exists the Norwegian Channel, and, inside it, deep fjords where the 

 bottom temperature is almost unvaried throughout the year. The 

 Ijords, so far as the investigations hitherto made have shown, con- 

 tain a very poor Plankton. 



Finally we come to the seabord of the Northern Ocean which 

 lorms a most decided antithesis to the shallow Lim Fjord with its 

 abundant Neritic Plankton. If ones studies the Sea Charts, for 

 instance those of the coast of Nordland, one will find that very 

 tew, and then only small shallow parts are to be met with. The 

 numerous islands and rocks rise almost invariably perpendicularly 

 from a depth of 100 fathoms. 



At such a depth the temperature is almost unchanged through- 

 out the entire year; thus the observations taken off Lodingen during 

 the years 1879 — 81 (see Mohs, [87j, p. 91) at depths of 100 

 fathoms give the highest temperature (.July 79) at 6".6, tlie lowest 

 6 .3, the annual variation being, therefore, but 0".3 at the outside. 

 At a depth of 50 fathoms (92 metres), the variation is S^.B (B^.S 

 m October, B^.S in January). 



The boundary of the mud is too, off the coast of Nordland, 

 at still greater a depth, viz., 100 fathoms, than in the North Sea. 



In our opinion all these conditions must be very untavourable 

 to the formation of Neritic Plankton. 



In reality too, there are excessively few Neritic Diatoms on 

 ^le littoral of the Northern Ocean, compared with those on other 

 coasts. 



During the summer of 1B95, Hjoiit studied the Plankton, along 

 the entire coast, from July to September. The results derived from 

 his observations are to be found in Table 1, Stations 7 — 41. 

 loreover the "Hansteen'" collected a number of samples in June 

 1896 (Table 3, Stations 77 — 85), and the Swedish Expeditions to 

 Spitzbergen in 1896—97, collected Plankton off the Norwegian 

 coast in June and August 1896. and in May and July 1897. The 

 contents of these samples were examined by Cleve, and the results 

 published m Pettekssox and Ekmas's latest wfu'k [98] Tables 

 1—3, pp. 48—61. 



It will l,e j^gQj-j f].,)m .:^ii (,{■ tjiese tables that small quantities 

 •LNentic Diatoms ai-e to be met with, dui'ing sTiuuner, along the 

 Norwegian shores of the Northern Ocean. 



No great plentitude of individuals was to be found in any of 

 "" samples, and only a few of them contained, mainly, Neritic 

 species to any appreciable extent. One sample obtained off the 

 Trondbjem E>rd in May 1897, contained mfer alia, mainly Clue- 

 ^oceros dehih, and another sample obtained off Ranen Fjord on the 

 23rd May contained SMetonema costcdum. 



Somewbat richer is a sample from the harbour at Tromso, 

 obtained on the 12th June 1897, referred to by Clkve in his 

 Phytoplankton [97], p. 8. Its characteristic form is given as Ch. 

 contortum, which is a true Neritic species. Several of the species 

 wei-e found l)y Cleve to possess spores. With almost these few 

 exceptions, tlie samples are nearly entirely free of Neritic Diatoms, 



but, on the other hand, some contain great numbers of Peridins 

 and Crustacea, and others some Oceanic Diatoms, especially Hhi- 

 zosolenia alata, f. gracillima (Ehizosolenia gracillima, CI.) which on 

 the West Coast are characteristic of the Baltic current in summer. 

 See our Table 1. 



Hjoet found that the Peridins and Crustaceee increased in 

 numbers as autumn were on, as the water became warmed in the 

 neighbourhood of the land. Possibly the Peridins here replace 

 the wanting Diatoms, and in place of them make use of the light 

 and warmth of summer in forming a stock of nutritious elements 

 which benefit the other organisms of the ocean. 



It is especially Ceratium tripos that occurs in great numbers*), 

 it being a hardy and contented species which is to be found almost 

 every where in the North Atlantic Ocean at all times of the year. 

 It is, therefore, so far Oceanic, being entirely independent of the 

 bottom. On the other hand, it probably requires so high a tem- 

 perature to promote a great development as that which in high 

 latitudes is only met with along the coast during summer. It 

 may, therefore, with us, with a certain amount of truth, be called 

 Neritic, as it mainly appears on the coast. 



The variety longipes developes itself under opposite conditions, 

 especially on our coasts, winter and spring, when the coastal water 

 is cooled, and the variety arctica is the characteristic form in the 

 Arctic seas. 



During the winter, our Northern Ocean shores are still less 

 prolific in Neritic species than during the summer. 



Of the numerous samples collected by Noedgaakd in February, 

 March and April 1896—97 (Table 5, Stations 186—198. Tables 

 6 and 8), there are but some few (from lieine in Lofoten, Station 

 215 and Stations 529 — 30, 1st April 1897) which contain Neritic 

 species, and these few species only in small numbers. The species 

 which are to be found at that season are Arctic diatoms such as 

 Chcetoceros furcellatum, Thalassiosira hyalina, and Fragilaria oceanica, 

 as well as some which also on our west and south east coast 

 appear as winter forms, such as Thalassiosira Nordenslcidldii, Th. 

 gravida, Chmtoceros sociale, dehile, diadema. 



All these species are likewise to be met wfitli off the coasts 

 of Greenland (see Gkan, 97. 2 — 3). 



In March 1898, Gean found the same species in somewhat 

 greater numbers along the coast of Sondmore and Komsdal up to 

 the mouth of the Trondbjem Fjord. This characteristic Plankton 

 Flora thus appears to be spread along the whole of our Northern 

 Ocean seabord during March and April, its southern boundary then 

 app)earing to be at Stadt. 



Neither in the number of species, nor in absolute quantity can 

 it compare with the Plankton Flora wliich springs up at the same 

 season in the Lim Fjord, the Cattegat, the Skagerak or even on 

 the West Coast, and which gives nourishment to all the Pelagic 

 forms of larva which commence developing in spring. 



Greater or lesser numbers of a remarkable Flagellat, Phaeo- 

 cystis Foucheti, (Har.) Lagerh., are almost invariably to be found 

 together with these Arctic neritic forms. Its development is as yet 



*) The various varieties of tliis species (var. macroceros, longi^jcs, arctica, 

 Buceplialos) are not separated m most of the Tables. 



