136 



U.S. NATIONAL MUSEUM BULLETIN 291 



ever, exceeds 34.75 %o. Therefore, the Antarctic population of B. dbys- 

 sicola occurs very prominently in the layer of maximum salinity. 



The greatest frequency of tows and individuals occurs on the density 

 histogram between sigma-t= 27.70 and 27.85 (fig. 41). Forty -two per- 

 cent of the individuals, taken by 43% of the tows, occupy 27.80 to 

 27.85 and 29%, from 18% of the tows, occupy 27.70 to 27.74. Eighty- 

 three percent of the individuals were captured in high densities greater 

 than sigma-t= 27.70. 



The histogram for oxygen (O2) concentration shows two peaks of 

 abundance (fig. 42). The first peak occurs at the 4.00-4.14 ml/L incre- 

 ment where 14% of the total captures accounted for 24% of the speci- 

 mens. The second peak lies at the two increments between 4.45 ml/L 



t ^ ^ ^ . ^ . jvsxv^x^XXVvX> 



.49 .5 .59 .60 



Salinity 34. %o 



Figure 40. — Frequency of captures and individuals of Bathyteuthis ahyssicola at salinity 

 increments in the Antarctic Ocean. Hatched area is number of captures (n=136); clear 

 area is number of individuals (n = 591); Crosshatch and dots are breakdown of captures 

 and individuals by .03%o. 



