436 M. Sars on the Distribution of Animal Life 



and has been long ago observed to exist. The cause has been 

 sought in the similar conditions of life in either case, although 

 it must be admitted that little can be said on this subject till 

 the facts are more clearly known. There are, likely enough, 

 also in both faunse not a few identical genera ; but I have seen 

 no satisfactory evidence of any full identity of species. Loven 

 expresses himself on the subject with some hesitation when he 

 speaks of an almost specific identity^ which, in fact, is no iden- 

 tity at all, for the very idea of identity implies completeness. 

 Finally, to conclude with Loven, to judge of all the seas in the 

 world from the analogy of the Antarctic and Arctic Seas seems 

 to me rather hasty. These hasty conclusions will perhaps 

 soon disappear when the detailed evidence on which they are 

 supposed to rest is published, which we may soon expect from 

 the distinguished vSwedish naturalists. This uniform fauna of 

 Loven's begins 60-80 fathoms deep. Such a boundary line 

 between the deep-sea and surface fauna it is impossible to 

 draw. As has been already stated, there are many of the 

 species dwelling in our shallow water which extend down to 

 the greatest depth reached on our coast (commonly 300 fath.). 

 Next appear decided deep-sea species, which at least range 

 downwards to 300 fath., in very marked depth, and not at all at 

 at 60-80 f. Such, e. y., are the great corals, Loplielia proUfera^ 

 Ulocyathus arcticus^ Primnoa lepadifera, and Paragorgia ar- 

 horea (100 f.) ; with which Pennatula borealis, FunicuUna 

 finmarchica^ and F. Ghristii first appear at 200 f., and Mopsia 

 borealis at 250 f. Of Echinodermata, Eckinocucumis typ>ica 

 at 100 f., Stichopus nafans 200 f. Of Polyzoa, Flustra abys- 

 sicola and Halilophus mirabilis at 100 f. Of Conchifera, Axi- 

 nus p)usillus at 200 f., Lyonsiella at 100 f,, and Yoldia obtusa 

 at 250 f. Of Cephalophora, Dentalium agile at 250 f. Of 

 Crustacea, Cytherella abyssorum,^ Cythereis mucronata^ Con- 

 choecia elegans^ Cyclaspis longicanda, and Pasiphae norvegica 

 at 100 f. On the other hand, Cyfberopferon Jiamatum, Ilya- 

 racJina coronata, Hemimysis abyssicola, and Pseudomma roseum 

 first show themselves at 250 f. And, lastly, Conchoccia borealis^ 

 Clydonia borealis^ and Cryptocheles abyssicola have hitherto 

 been found only at 300 f. 



Then with respect to the deep-water fauna living on the 

 coast of Norway, so far as we are acquainted with it, it seems, 

 instead of agreeing perfectly with the very little of that we 

 know from other seas, much more to show itself to be p)&cu~ 

 liarly and characteristicaJly northern^ as much as can be de- 

 sired. To mention some of tlie more striking forms, where 

 out of the North Sea have been found Trichostemma, Lophelia 

 prolifera^ Ulocyathns^ F^mgiacyathus, Primnoa, lepadifei^a^ 



