794 



BULLETIN OF THE BUEEAU OF FISHEEIES 



with our own data for 1914 (fig. 145) to show the isohalines for 35.5 and 36 per mille 

 departing farther and farther from the continental edge, passing eastward from 

 Georges Banl^, and so leaving a less saline wedge (34.5 to 35.5 per mille) some 60 

 miles wide off the mouth of the Eastern Channel. This fact is worth emphasis as 

 one of the numerous bits of evidence that the indraft that takes place into the east- 

 ern side of the gulf, via this channel, is constantly of the so-called "slope" origin 



Fia. 156.— Salinity profile running from a station (10213) off northern Cape Cod, southward across the western end of 

 Georges Bank (stations 10215 and 10217), to the continental slope (station 10218), July 19 to 21, 1914 



(p. 842), thus accounting for the rarity of tropical planktonic animals and plants 

 within the gulf (Bigelow, 1925). 



When the transition in saUnity is as abrupt along the edge of Georges Bank as 

 it was in July, 1914 (fig. 156), to speak of a salinity "wall" is excusable exaggera- 

 tion. At such times the following waters may be named, successively, along any 

 profile crossing Georges Bank from north to south: 



