RESULTS OP DEEP-SEA DREDGING IN ZETLAND. l79 



former occasions with respect to the geographical distribution of the marine 

 fauna of Europe. A yachting excursion which he had taken in the course 

 of this summer, accompanied by two scientific friends, to the northernmost 

 part of the British Isles, together with an examination of the upper tertiaries 

 in SufFoliv and Norfolk which he had since made in company with Mr. Prest- 

 wich, gave the author a better insight into the scope of such distribution 

 than had resulted from his previous researches, and confirmed his belief that 

 the division into separate areas or " provinces," which had been proposed 

 by so many systematists (all of whom held different opinions as to the ex- 

 tent and limits of such " provinces "), was erroneous, and that the present 

 distribution must be referred to a state of things which has indeed passed 

 away, but left a very distinct impress of its action. The author is inclined- 

 to take the Coralline Crag as a starting-point, and to consider the marine 

 fauna of Europe, Northern Asia, the Cis-Atlantic zone of Africa, and part 

 of North America, as having been closely related at a comparatively recent 

 epoch, and as forming one common area of origin. Many species of Mol- 

 lusca once existed at botii extremities of this vast district — e.g. Mya trun- 

 cata and Buccinuni undatum ; and other species hitherto supposed to be 

 restricted to the Mediterranean (viz. Monodonta limbata and CeritJiium vid- 

 gatiim, with its variety C.calabrum) have lately been discovered by Professor 

 Sars on tiie coasts of Finmark. It is also probable that the recent exploration 

 of the Greenland seas by Otto Torell and otliers may reveal further instances 

 of a similar kind. Very little has hitherto been done towards the investiga- 

 tion of the Arctic fauna. It by no means follows that an extremely rigorous 

 or " arctic " temperature prevailed in those places where we find the remains 

 of some Mollusca which now inhabit only the seas of colder regions, or, vice 

 versa, that the presence in tliese regions of fossil shells belonging to species 

 which now inhabit only more southern seas indicates the former prevalence 

 of a warm climate. The temperature of the sea at certain depths is well 

 known to be very equable ; and it is only littoral or shallow-water species 

 that would be exterminated or affected by a change of climate. Some kinds 

 appear to be more hardy than others, and to have survived considerable and 

 perhaps frequent changes of temperature; while others have undergone a 

 limited modification of form, and are considered by some naturalists as 

 distinct (or "representative") species. A great deal, however, yet remains 

 to be done, by accumulating facts, and a critical comparison of recent with 

 fossil species, before a complete or satisfactory theory of distribution can be 

 established. 



Mr. Jeffreys contrasted his experience of this dredging expedition wifli 

 those he had made to other parts of the British coasts as well as to the 

 Mediterranean, and also with the accounts he had received of similar expe- 

 ditions to the coasts of Norway and Sweden — showing the far greater 

 difficulties which attended an exploration of our northernmost sea, by reason 

 of the variable and often tempestuous weather, and of that line of coast being 

 unsheltered from the prevailing winds. He, however, succeeded in procuring 

 three species of Mollusca new to science, which he proposed to name Mar- 

 garita clegantula, Aclis Walkri, and Nassa ? Haliaeti, besides twelve other 

 species which were new to the British Isles. Of these last, ten are Scandi- 

 navian, one is Mediterranean, and the other had hitherto been known only 

 as a Crag fossil. He reserved the description and particulai's of these species 

 for a work on British Conchology which he had undertaken. He ascertained 

 that the Gulf-stream never impinges on any part of the coast which he had 

 examined, although the climate was temperate. 



■ The author noticed the occurrence at considerable depths (nearlv 80 



n2 



