242 bulletin: museum of comparative zoology. 



its low salinity and temperature, and by the Arctic members of its 

 plankton (p. 248), as a branch of the Cabot Current. At that season 

 its effect is traceable as far west as the Eastern Basin of the Gulf; and 

 its main line of dispersal was evidently west, not north toward the Bay 

 of Fundy, neither salinity (Fig. 65), temperature (Fig. 53) nor plank- 

 ton (p. 248, Fig. 81) affording any evidence of it north of Yarmouth, 

 off the west coast of Nova Scotia. This branch of the Cabot Current 

 dwindles rapidly as the season progresses. In June there is very 

 little evidence of it, either in salinity or temperature, on the surface 

 of the Gulf (Fig. 89), while the area then influenced by it in the mid- 

 depths (32.5%o) is less extensive than in May. And in August and 

 September no trace of it has been detected west of Cape Sable, at any 

 depth. In the latter month the main branch of the Cabot Current 

 still reaches Brown's Bank and the Northern Channel (p. 22). But 

 it is so much narrower off Shelburne then than in June, or in August, 

 as to suggest its entire obliteration there in autumn. 



No satisfactory records of the winter temperatures and salinities 

 of the eastern half of the Gulf (1914a, 1915), are yet available. But 

 the facts that river freshets, and melting ice indicate a spring or 

 early summer maximum for the outfiow from the Gulf of St. Law- 

 rence, and that there is nothing in the winter temperatures salini- 

 ties or plankton of the western side of the Gulf (1914b) to suggest the 

 influence of the Cabot Current, together with its fluctuations as just 

 outlined, forbid the idea that it enters into the Gulf in appreciable 

 amount at any season except spring. 



I have already pointed out (p. 238) that the branch of the Cabot 

 Current which reaches the Gulf is very superficial, due to its compara- 

 tively low density, hardly influencing hydrography below, say, 50 

 meters; and since this low density is retained by this northern water 

 as long as it is recognizable in the Gulf, there is no reason to suppose 

 that it ever sinks into the basin of the latter, which explains not only 

 the comparatively high bottom temperatures of the basins, but the 

 absence of Arctic elements in the plankton there. 



The relative importance of offshore water, is, roughly, the reverse 

 of that of river, and of the Cabot Current water, of which it is the anti- 

 thesis in salinity, increasing from spring to summer as the latter 

 dwindle. It is certain that the influx takes place chiefly in the eastern 

 side of the Gulf (p. 238): and our records, so far as they go, suggest 

 that in the upper layers it is at its maximum there in August (p. 225) ; 

 diminishing in autumn. But we know so little about the hydrography 

 of the eastern half of the Gulf in the latter season, or winter, that 



