46 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



similar. In opposition to this " bipolar hypothesis, " I 

 pointed out last session that in the Tunicata at least there 

 was no special resemblance between the far northern and 

 far southern species, and that, on the other hand, there 

 was a marked similarity between a series of forms from 

 the North Pacific and those from the North Atlantic. 

 Sir John Murray answers me, in a letter on the subject, 

 " I think your remarks quite just. I expect many cases 

 of north and south distribution will be knocked on the 

 head by further discoveries, and that many cases of 

 bipolar distribution not yet evident will be brought to 

 light." Well, we want now to determine how far that is 

 the case. We both agree that what is needed is further 

 facts — more investigation. 



There is every prospect that the Antarctic Seas will be 

 fully explored. Several expeditions — Borchgrevink's and 

 others — are there or will be soon, still others are in 

 prospect. The Tunicate fauna of Australian seas is fully 

 as well-known as that of Europe, the marine fauna round 

 Kerguelen Island, thanks to the "Challenger" explora- 

 tions and Sir John Murray's writings, is better known 

 than that of Iceland, whilst of most of the inhabitants of 

 the seas around Spitzbergen we are practically ignorant. 



Moreover, Nansen has opened up a new problem in 

 northern marine exploration. He has shown that a deep 

 sea basin occupies a part at least of the polar area. Where 

 does that basin begin, and how far does it extend ? How 

 does it end towards Norway, Iceland, and Greenland? 

 The sea immediately to the north and west of Norway is 

 shallow, running out gradually to a depth of about 200 

 fathoms, and then, according to Mohn, descending steeply 

 to the bed of the deeper ocean, which reaches a depth of 

 2000 fathoms or more. We do not yet know the limits 

 nor the inhabitants of that deep basin. In advocating 



