1911] Michael: Chaetognatha of the San Diego Region. 151 



This table shows clearly that the species rarely occurs above 

 25 fathoms, and that it increases in abundance and frequency at 

 least down to 250 fathoms. In 25-35 fathoms, however, there is 

 an irregularity in the increase and it is interesting to notice that 

 when the night hauls are eliminated this irregularity disappears 

 This is shown in table 59. 



TABLE 60 



Night Distribution of S. lyra (6 p.m. to 6 a.m.) based on Surface and 



Horizontal Closing Net Hauls. 



Table 59 shows that during daylight the species occurs 

 rarely above 40-75 fathoms, and that it increases regularly in 

 abundance from nine in 25-35 fathoms to 102 in 250-350 fathoms. 

 The increase in frequency is more irregular, but this is to be 

 expected because so few successful hauls were made. "When 

 compared with the night distribution, as shown in table 60, the 



