136 University of California Piihlications in Zoology. [Vol.8 



over 33.648, and still less when the salinity is below 33.605. It 

 would be interesting to tabulate data concerning salinity with 

 respect to temperatures varying from 15?9 to 17?5, and from 

 19?6 to 21?5, but the few hauls made under these conditions 

 make this impossible. 



In spite of the apparent significance of these data it may be 

 argued that the hauls were distributed irregularly with respect 

 to light. Consequently, if more night hauls were made when the 

 salinity varied from 33.605 to 33.648 than M'hen it was outside 

 these limits, the greater abundance and frequency noted might 

 be due to the effect of light and not to that of salinity. The 

 following tables indicate that this is not so. 



TABLE 47 



Effect of Salinity on Distribution of S. hipunctata with respect to Night 



(6 p.m. to 6 a.m.) 



Number of hauls Number Number of specimens Average 



^ -^ ^ of , ^ ^ Fre- tem- 



Salinity Total Successful hours Total Per hour quency perature 



33.604 or less 15 12 10.3 6284 610 79 18?9 



33.605-33.648 13 11 9.2 6763 735 85 19?6 



33.649 or more 13 10 12.1 7264 600 77 19? 1 



TABLE 48 

 Including only hanls made when Temperature varied from 17? 6 to 19? 5 



Number of hauls Number Number of specimens 



,. -^ ^ of r '^ ^ Fre- 



Salinity Total Successful hours Total Per hour quency 



33.604 or less 10 7 7.7 2329 302 70 



33.605-33.648 7 6 6.95 5945 841 86 



33.649 or more 11 9 10.6 6646 627 81 



From these tables we see that, after day hauls are eliminated 

 from consideration, S. hipunctata still persists in being more 

 abundant and frequent on the surface when the salinity varies 

 from 33.605 to 33.648. Furthermore, after the antagonistic 

 effects of variable temperatures are eliminated by tabulating only 

 those night hauls made when the temperature was between 17? 6 

 and 19?5, table 48 shows increased correlation between abund- 

 ance and frequency of the species and salinity of the water. 



There is still a possibility that a maximum number of hauls 

 corresponding to salinities between 33.605 and 33.648 were made 



