52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I49 



be divided into near-shore (<20 m.) and offshore (>20 m.) 

 assemblages. In terms of numbers of living individuals, the near-shore 

 areas (10-20 m.) average 177 per sample, while the offshore areas 

 (20-40 m.) average 62. At depths of less than 10 m. the living popu- 

 lation has an average of 335 individuals per sample. 



Riley (1959) has shown that the western end of the Sound is 

 usually about 3-5%o fresher than the eastern end. The increase in 

 foramini feral species to the east is most likely due to the more oceanic 

 conditions found there and to the proximity of the open ocean from 

 which migration into the Sound can occur. 



In L.I.S. the concentration of nutrients and phytoplankton increases 

 to the west (Riley, 1959). The significantly larger living popula- 

 tion in the E. advena zone of traverse 2 is probably related to the 

 potentially greater food supply in the western area. 



To relate the foramini feral zonation with depth to environmental 

 factors is more difficult. Riley (1956, pp. 17, 18) has shown that 

 the seasonal cycle and range of variation in temperature and salinity 

 at near-shore (8-12 m.) and offshore (19-28 m.) stations in the 

 central part of L.I.S. are about the same. Moreover, the seasonal 

 cycles and range of variation in phosphate, nitrate, and oxygen at 

 near-shore and offshore stations do not show significant differences 

 (Riley and Conover, 1956, pp. 51, 52, 54). Since the Foraminifera 

 are holozoic, the seasonal cycle and amount of nutrients should affect 

 them only insofar as it affects the organisms upon which they feed. 

 Very little is known concerning the oxygen requirements of the 

 Foraminifera. At several stations a strong odor of H 2 S emanated 

 from the black muds in the cores, and at some of these stations the 

 living population was abundant. Riley (1959) has indicated that 

 minimum values of oxygen for bottom water are about 40 percent of 

 saturation. It would appear, then, that although reducing conditions 

 may be prevalent in the sediments below the surface, the sediments 

 at or near the surface (within 1 cm. or so) are not oxygen deficient. 



The pH and Eh of the sediments have not been investigated during 

 the present study. McCrone and others (1961) have shown that 

 the pH is usually about neutral, whereas the Eh is negative. They 

 did not indicate any differences between near-shore and offshore 

 stations. 



I have already pointed out that in L.I.S. both the distribution of 

 species and the number of living individuals bear no relation to the 

 particle size of the sediment. 



