The turrid Afuria is a splendid example of a bipolar genus that 

 " goes deep " over the warm zones, i.e. — 



A. okhotskensis , 50°-60° N. : 73 fathoms; bottom temperature, 



30-9° F. 

 .-1. persimilis, 1° N. : 741 fathoms ; bottom temperature, 384° f. 

 A. magnifica, 64° S. : 152 fathoms; bottom temperature, 

 32-38° F. 

 Certain littoral genera, Liriola (Northern) and Kerguelenella (Southern) 

 are closely related, but no longer have a connected range. They have 

 not " gone deep," which raises the question, were the cold water faunas 

 of both hemispheres sufficiently close during periods of Pleistocene 

 glaciation to allow of interchange of species ? 



Summary (jf Discussion 



Dr. Hubbs commented on the peculiar pattern of avoidance of the 

 Antarctic Continent claimed by Mr. Powell in the three genera discussed, 

 and asked whether that might not represent polar extinction, rather 

 than invoke the use of a series of land-bridges. In answer it was pointed 

 out that there is no evidence on the Antarctic Continent of forms 

 related to the three under discussion (two of which are deep water), 

 and that the alleged land-bridge mentioned is actually a ridge at a depth 

 of 2,000 metres. This ridge, or series of ridges, may have been much 

 shallower during an earlier period. 



330 



