532 



BULLETIN OF THE BXJEEAU OF FISHERIES 



eastern end of the bank (fig. 16), however, shows much less contrast in temperature 

 between the two sides of the latter, with the oceanic water (warmer than 8° and 

 Salter than 34 per mUle) so much farther out from the edge of the continent that 

 even the outermost station (20069) did not touch it, leaving the bottom down the con- 

 tinental slope bathed with water colder than 5° at all depths. The profiles thus 

 corroborate the temperature charts (figs. 12 and 13), to the effect that the warm 

 bottom zone was obliterated somewhere between longitudes 67° and 68° W. (about 

 midway the length of Georges Bank) in February and March by the "cold wall" 



Meter 



Temperature, Centigrade 



2° 3° 4° 5° 6° 7° 8° 9° 10° 11° 12° 13° 14° 15° 



Fig. 10.— Vertical distribution of temperature near Lurclier Shoal in various months. A, March 23, 1920 

 (station 20032); B, April 12, 1920 (station 20101); C, May 10, 1916 (station 10272); D, August 12, 1913 

 (station 10096); F, August 12, 1914 (station 10246); Q, January 4, 1921 (station 10500) 



that wedges in between the slope and the oceanic water. As it is the existence of 

 this warm zone that permits the year-round existence of warm-water subtropical 

 invertebrates and of the tilefish along this stretch, the definite location of its eastern 

 limit is a matter of some biological importance. The contrast between the graph 

 for our outermost station off the western end of Georges Bank and two other deep 

 stations off its eastern end and off Shelburne, Nova Scotia (fig. 18), is an addi- 

 tional illustration of the sudden dislocations about midway of the bank, with a 



