244 



0. Nordgaard. 



of year, as is the case in the northern latitudes. 1 ) And if this be 

 a fact, its influence will be seen on the plankton-eating animal world. 

 It is possible that the suitability of the molluscs as zoographical 

 character-forms, depends upon the fact that a great many of them 

 are plankton eaters. The mud-eating worms, for instance, are much 

 less suitable in giving a characteristic of the fauna. Besides, there 

 are species of mudeaters with a small geographical distribution. A 

 star-fish. Ctenodiscus crispatus, whose stomach is almost always full 

 of mud. is very little found beyond the arctic district. In such 

 cases, one is compelled to conclude that the animal has very little 

 power nf adaptation. 



Further Remarks on Plankton. 



In the fiords near Bergen, February is the month in which 

 the plankton is poorest, and there is reason to think that the 

 minimum for the year, for the northern fiords of Norway, also falls 

 in this month. The great change in plankton life occurs at the 

 spring inflow of the diatoms. 



In the fiords near Bergen, March is the month when the dia- 

 toms begin to show themselves en nias.se. but at different times, 

 within the limit of this month, from year to year. It is not yet 

 possible definitely to fix the time when the winter state gives way 

 to the spring one in the northern fiords, but it is probable that 

 the spring-diatoms appear in very large quantities somewhat later 

 here than in the south west fiords. Below I give some data con- 

 cerning the occurrence of diatoms on the northern coasts. 



In the Tys Fiord on 29 / 3 1899 only a few diatoms were found, 

 but on y 4 they were numerous near Lille Molla, and this was also 

 the case on i j i in the same year at Hola near Svolvser. 



'% 1899. In the harbour at Stene in P>o (Vesteraalen) many 

 diatoms, 0—3 m. 



'- 4 1899. The Malangen Fiord, many diatoms. Whilst there 

 in Malangen. from 12th — 14th of April 1S99. was a rich develop- 

 ment of diatoms, in Kvtenangen on 19th of the same month, winter 

 conditions prevailed. But on -'/ 4 the sprint; diatoms also had shown 

 themselves in Kvaenangen. 

 - :: 4 1899, Trold Fiord harbour, many diatoms. 

 - 4 4 1899, Ingohavet. many diatoms. 



1899, Repvaag harbour, diatoms. 



1899, The Porsanger Fiord, many diatoms. 



1899, Mehavn, diatoms. 



1899, Vardo. some chains of diatoms. 



1899, Hola near Svolvaer, few diatoms. 



At the place last mentioned (in Lofoten) the first rush of 

 diatoms was over. In place of them, there were multitudes of 

 forms in different stages of development belonging to Copepoda, 

 Cirripedia, Annelida etc. 



development of the spring 



26/4 



'A 

 7s 



!0 ill.. 



1900. The Ostnes Fiord. 



diatoms. 

 1900, The Vest Fiord. — 25 m.. many diatoms. 

 I '.tin i. The iSkjerstad Fiord, still winter conditions. 

 190O, The Salten Fiord, many diatoms. 

 19(10. The Folden Fiord, still winter conditions. 



Previously in this treatise, it has been shown that the Vest 

 Fiord is the most important terminus for a great number of south- 



6/ 



I 



] ) Both large and small animals, from the Spitzbergen-reindeer to the 

 plankton- crustaceans, rind that winter in the arctic zone is a time when food 

 is scarce. 



ern bottom forms. It is probably also the case, if one substitutes 

 plankton forms for bottom animals. North of the Vest Fiord such 

 species as Pleuromamma robusta, Dahl. and Candacia armata, Boeck. 

 will hardly be found. In the Norwegian series of fiords. Eu- 

 chasta norvegica, for instance, is not found north of the Vest Fiord, 

 but I took specimens of Chiridius armatus in Malangen. 



The very large quantities of such Siphonophora as Ciipulita 

 sarsi and Physophora borealis along the northern coast and in the 

 northern fiords during the winter of 1899, was an occurrence which 

 merits further mention. Of the forms mentioned, Cupulita sarsi 

 was exceedingly common. On 2 % 1 saw in the Jokel Fiord (arm 

 of Kvsenangen) a fisherman whose gloves on the inside were stri- 

 ped red by the remains of this siphonophor which had fastened 

 itself to the fishing lines. The inhabitants looked upon this as 

 being something unusual, which points to the fact that the pheno- 

 menon is not of annual occurrence. As the plankton species in 

 question are oceanic, their occurrence in large quantities in the 

 fiords can hardly be explained in any other way than by supposing 

 that there had that year been an unusually strong flow of the 

 current in the upper layers of water in the sea towards the coast 

 and into the fiords. It occured to me to connect this with the 

 prevailing winds. To be able to form an opinion of the relation 

 between the sea and land winds, wo will look at the downfall 

 for the period in question. 1 ) 



Downfall from October 1898— March 1899. 



As it is more especially the ocean winds which cause down- 

 fall, one must be justified in concluding that, from October 1S98 

 to March 1899, their influence on the coast line in question must 

 have been greater than usual. But this would again result in more 

 than the ordinary quantity of water being driven in from the sea 

 coast, which must be evident in the kind of plankton which occurs. 



In this connection, it is also interesting to recall that, on the 

 south west coast of Norway (in the spring-herring district), the 

 fishermen call some Salphce „silderaek", 2 ) and they look upon their 

 appearance as a sure sign that the herrings will come in shoals 

 to the coast. It is not altogether impossible that scientific investi- 

 gations will verify this prognostication. At any rate, it appears to 

 be quite reasonable, that the prevailing ocean winds stir up sur- 

 face currents which drive both herrings and their food towards the 

 coasts. 



'' Cf. Nedbariagttagelser i Norge. Aarg. IV (1898) og V (1899). 

 2 ) From sild (herring) and reka (to drift with the stream). 

 Cf. M. Sars, Fauna littoralis Norvegiae, Part I. p. 63. 



