118 University of California Publications in Zoology. [Vol. 8 



TABLE 37 



Table -showing the effect of Day and Night on Distribution of 

 S. bipunctata 



.Daylight, or 6 a.m. to 6 p.m. 



Night, or 6 p.m. to 6 a.m. 

 58 48 42.3 22,794 539 83 



This table shows that the ratios between the average number 

 of specimens per hour obtained during the day and the average 

 number obtained during the night are as follows : surface 1 to 

 5.0; 4-6 fathoms 1 to 3.0; 7-12 fathoms 1 to 2.6; 15-20 fathoms 

 4.8 to 1 ; 25-35 fathoms 12 to 1 ; 40-75 fathoms 14 to 1. Further- 

 more, the frequency in each depth during the day is to that 

 during the night as 62 to 83 on the surface, 60 to 67 in 4-6 

 fathoms, 25 to 57 in 7-12 fathoms, 100 to 100 in 15-20 fathoms, 

 42 to 43 in 25-35 fathoms, and 33 to 25 in 40-75 fathoms. To 

 sum up. these data show that during the night S. hipunctata is 

 more frequent and abundant between the surface and 12 fathoms, 

 while it is less so between 15 and 75 fathoms. This probably 

 means that the species migrates in greatest number from all 

 depths below 15 fathoms toward the surface during the night, 

 while during the day it migrates in greatest number from all 

 depths above 15 fathoms toward deeper water. 



