196 bulletin: museum of comparative zoology. 



most striking feature, apart from the separation into comparatively 

 fresh water on the continental shelf, and much Salter oceanic water 

 on the slope, is a succession of zones of comparatively uniform salinity 

 alternating with zones in which there is a rapid change in salinity both 

 vertical and horizontal. Next the shore there is first a mass of bottom 

 water of 33.2%o, fifteen fathoms thick (Station 10063), separated 

 by a zone of rapid transition from a much fresher though hardly less 

 uniform surface zone of about 33%o (Station 10062), some twenty-five 

 fathoms thick. This, in turn, gives place to much salter water, over 

 the edge of the shelf (Station 10061), where salinity increases only by 

 .2%o (33.41%o-33.62%o) from the surface down to fifty fathoms; 

 below which there is a sudden rise. Since some of these masses of 

 uniform water reappear in other profiles, it is convenient to designate 

 them from the shore seaward, as A, B, and C. 



On the profile from the neighborhood of New York to the slope, in 

 about latitude 40° (Fig. 39), the salt ocean w^ater is much more in 

 evidence than it is further east, water of 35%o bathing the slope nearly 

 to the fifty fathom curve, although the surface water at the shore 

 end is about the same salinity as in the last profile (Station 10067, 

 31 .2%o) . Two of the bands, which were noted in the preceding profile, 

 reappear here, i. e., A. and B, with about the same salinities which 

 characterized them further east. Band A is as well defined as in the 

 preceding profile, occupies the same relative position on the shelf; 

 and has the same salinity (33.2%o)- But in the present profile the 

 transition to the fresher water near shore is less sudden than it was 

 further east. Band B is less clearly defined than in the preceding 

 profile, and its salinity is less uniform, both vertically and transverse to 

 the continental shelf, though of the same general value (about 33%o) ; 

 nor does it so nearly reach to bottom, but overlies a layer of much 

 Salter water. Nevertheless the band is distinctly more uniform than 

 the water immediately below, or on either side of it; hence its indi- 

 viduality still deserves recognition. But the third band, C, which 

 characterized the outer part of the preceding profile, can not be dis- 

 tinguished in this one. As a whole the surface is fresher along this 

 profile than the preceding; and this is true even of its off shore end, 

 although the bottom water near the edge of the shelf is much salter 

 than further east. And not only is water salter than 33.2%o nearer the 

 surface over the middle of the shelf, but water with salinity of 33%o 

 and higher washes the bottom to the fifteen fathom, instead of only 

 to the twenty-five fathom curve. All this shows that off New York 

 shore water was more in evidence on the surface, Atlantic water on 



