•_'4.! 



Those who have consiilcnMl tliis (jucstion seem to have forgotten 

 that also A. E. Vekkim, has ixpicssed an opinion with refercnee to 

 transportation by ice. 



In 18K;3. (Ire(li;ini;s weiv niailc tVoiii SS ..All)atross" in the 

 region of the (iiilf Stream fiuni oD' ("ape llatteras to Nova Sentia. 

 In tile ..I\esults of tiie P^xplorations" (p. 507) Veukim, writes: — 

 ..In many instances we iiave also dredircil pebbles and small, ronniled 

 bowlders of i;ranite and cither crystalline rocks from liciicath the 

 Gulf Stream in deep water. These, I snppose, have lircii carried 

 to that reyion by sliorc-iee tloatioir off in i^rcat (luantities trom our 

 northern coasts in wintei- and sprin<;-, and meltinL;- where the warm 

 (nilf Stream water is encountered." From this, it will be se('n 

 that Vkkrili, inclined to the opinion that the pebbles found in the 

 deep water were broug-ht thither by tloatini;- ice, and if tiio ice 

 takes along- pebbles, there is nothin>;- to hinder for its also taking 

 along shells from the coast. 



. In the Norwegian fiords, it is highly probable that drift-ice 

 causes a transportation of littoral shells out into the deep basins. 

 For instance, Litturina rndis and ohtunsata found at a depth of 

 150—180 m. on Risværflakot, and Gibbnla cineraria at a depth of 

 000 meters in the Oxsund, (in each case the shells were empty) 

 were neither of tiiem in their primary locality. Hans Kiæe,') too, 

 has given a very plausible explanation of the storing of gravel and 

 shells in the snow and ice on the shore, and their conveyance to 

 places farther off when the ice melts in the spring; his explanation 

 is based upon personal observations at Tromsø. 



Fauna and Hydrography. 



In the foregoing pages. I have ti'ied to pi-ove that there is a 

 close connection between fauna and hydrogi'aphy. It would from 

 this again appear, that a majority of species of animals have an 

 organisation which can only bear a very slight variation in hydro- 

 graphical conditions. The number of socalled cosmopolitan species 

 is very small, and it seems to me that the number of those which 

 are mentioned as being widely distributed is also on the decrease. 

 The more exact moiphological investigation which is demanded now- 

 a-days often results in the dividing of a species into two or more. 



And this is the case, not only with bottom forms, but also 

 with reference to plankton. 



I will give some instances of what I mean. We have for years 

 heard that Calanux finmairliiciif' is found in nearly every sea. But 

 G. 0. Saks-) now tells us that under the name C. fimnarchicus 

 was hidden another species, C. hclgolandicus, Claus, which is spe- 

 cially distributed southwards, while the former has an arctic and 

 boreal distribution. Strictly speaking, Calunns finmarchicus contained 

 three ditfereut .species, for Calantis hi/perhoreus was considered 

 to be a variety of C finmarchicus previous to the publication of 

 Dr. GiESBRECHTs well-kuown monograph on Copepods. Instead, 

 therefore, of one species distributed over nearly every sea, we now 

 get three species with comparatively limited distribution, C. hyper- 

 horeus being arctic. C. /inmdrchinis boreal and arctic and C. hel- 

 golandicux lusitanic. 



Similarly with respect to Euelia-ta. Instead of the widely di- 

 stributed Eucho'ta norvegica, we now have, norvegica, glacialis and 

 harhat'i. Examples might easily be multiplied from the Copepods. 

 On the other hand, it is l)eyond doubt that there are also deep- 



(Is whirh h 



^) Niveaufoviinilrin 

 -) Crustacea ot Xc 



• ti-ansijor 

 Vol. IV. 



exceedingly wiile distri- 

 liitioiis are (inly subject to very slight changes 

 and this too for extensive stretches. It is also 

 Illere are shallow-water forms which are .so 

 ai)le easily to adapt themselves to changes in 

 mil are thus able to exist under very diveisc 

 but Ihrii' nnniiier has undoubtedly been over 

 northern AmniUdn. (',. M. K. 



watei' jonns ul Co 

 butioii. Natnial en 

 at the -real d.'pth^ 

 very lirohahh' that 

 organized as to be 

 natural conditions, 

 jihysical conditions, 

 rated. In his excellent 

 I.iovinsen') says: — 



.,[ must say that I doubt whether the northern seas really 

 have so many species in common with the Mediterranean as would 

 appear from the lists given in the literature available." On account 

 of this doubt. Li:vinsen carefully comjKired the northern forms and 

 those from the Meditei'ranean, and come to the conclusion that Aroii- 

 rolii niariitii and Peetinaria fcorri/i from tiie latter sea were ditter- 

 ent from the northern species beaiin<: the same name. They were 

 given the iiaiiies .1. cliijmirdi and /' rohusfn. 



Similarly with respect to Fci-timiriu (niricoina, I'otdiniHa rnii- 

 formis etc. 



1 could give a number of examples from the Bryozoa too, to 

 show how the extent of the distribution of a species diminishes, as 

 the claim for greater exactness in the determination of a species 

 increases. The change which has taken place in the use of the 

 word „species" with regai-d to the Bryozoa. has had a similar effect. 

 F. A. Smitt, for instance in his work on boreal and arctic Bryo- 

 zoa, which in other respects is excellent, has used the word «spe- 

 cies" in a very extended sense. He has entered as „forms" a large 

 number of specimens which are given the rank of „species" by 

 recent systematical investigators. 



As a result, Smitt's species Avere attributed with a much too 

 extensive geographical distribution. 



The distribution of a species is undoubtedly dependent on many 

 other things than the temperature and salinity of the water in which 

 it exists. Currents especially have both a direct and indirect in- 

 fluence. If one considers the conditions on the Norwegian coast, 

 where arctic and boreal fauna meet, the question naturally suggests 

 itself: — Is it the arctic or the boreal animals which on our coasts 

 are gaining ground? 



To settle whether the movements of a given element of fauna 

 or flora are progressive or retrograde, one can examine the currents 

 in the adjoining sea. On the Norwegian coast, the current which flows 

 in a northerly direction is predominant, and the southern animal forms 

 are carried along with it. On tlie east coast of North America, 

 the reverse is the case. The duration of the pelagic state is also 

 important with regard to the penetration of the species into new 

 districts. It would therefore seem likely that such species as Mgfi- 

 lus cdalis and Modioht modiohtg, in which the pelagic state hardly 

 lasts much more than a week, would find it difficult to g-et over 

 the space between two coasts Avhich ai-e separated by a wide 

 expanse of ocean. Along a length of coast line, however, these 

 and similar species are widely distributed, for. in tiie course of 

 thousands of years, the many small stejis forward amount to a 

 considerable distance. 



I do not know very much about the plankton in the more 

 southerly seas, but I have tiie. impression that there is not so much 

 difference there in its (luantity and quality at the difl'erent times 



') Systematisk geoavafisk Oversikt ovc 

 Chætognathi og Balonoglossi. At'tiyk at' \\ 

 Foren, i Kjf.benli.ivn 1882 o- 1883 (p. L'87). 



e nordiske Annnlafa. Geplii/rea, 

 skab. Mi-dd. fra dt-n naturliist. 



