XCviii INTRODUCTION. [CH. 



coast does not rest upon any foundation. I was satisfied, 

 by information which I obtained on the spot and in the 

 course of my di'edging-operations, that no submarine 

 cun'ent sets in that direction, nor any which could have 

 brought the shells from a distance ; and the same con- 

 viction is entertained l)y tlie able and zealous naturalists 

 who have so carefully and during several years in suc- 

 cession explored many square leagues of this remarkable 

 sea-bed. 



Gulf -stream. — This " deus ex machina" seems al- 

 ways to be called into requisition, in order to explain 

 any apparent anomaly in the distribution of marine 

 Mollusca. In the minds of many persons it ranks with 

 the comet in its mysterious effects. It is quite true that 

 the scientific world, and indeed all who take any interest 

 in the works of Nature, are under the greatest obliga- 

 tions to Commodore Maury for the lucid account he 

 has given, in his ^ Physical Geography of the Sea,^ of 

 this really wonderful phenomenon. But with regard to 

 the subject of the present inquiry, I cannot help express- 

 ing a doubt whether the effects of this great '' river in 

 the ocean '' have not been much overrated. 



The partial glimpse which we have hitherto been able 

 to obtain of the results from the recent expedition of 

 Otto Torell and other Swedish naturalists to Spitz- 

 bergen shows that the Gulf-stream was found not to 

 exert any influence on animal life in that region, it ap- 

 pearing to be entirely of a glacial nature *. From careful 

 inquiries which I made in several parts of the eastern 

 coast of Zetland last year, I was satisfied that the Gulf- 



* While tliis last sheet is passing through the press (22 May, 18G2), 

 Professor Forchhamraer has read before the Royal Society a valuable paper 

 on the composition and density of sea-water. His observations as to the 

 Gulf-stream tend to sliow that it cannot affect the distribution of animal 

 life in the lower zones of the sea. 



