156 



U.S. NATIONAL MUSEUM BULLETIN 291 



OXYGEN 



Figures 57-58. — Capture points of Bathyleulhis abysskola. Oxygen concentration ml/L. 57 

 (top). Vertical section, eastern Atlantic. 58 (bottom). — Vertical section, western Atlantic. 



southern limits of the Indian Ocean between Prince Edward and the 

 Crozet Islands. The last two records are considered to lie within the 

 influence of the subantarctic waters of the Southern Ocean and not in 

 an Indian Ocean w^ater mass. 



Chun's specimen from the Chagos region probably is B. hacidifera. 

 but the rest of his specimens are apparently B. abyssicoJa. The speci- 

 men of B. hacidifera was taken at about 2000 m in the transition zone 

 between the Indian Central Water Mass and the Indian Equatorial 

 Water Mass. Oceanographic data from Tressler (1963) indicate that 

 at 2000 m the temperature is about 3" C and the salinity is about 

 34.7T%o giving a sigma-t value of 27.75. The oxygen concentration 

 below the oxygen minimum layer is 2.75 ml/L; in the north the mini- 

 mum layer has values lower than 1.00 ml/L. Chun's specimens of B. 

 ahyssicola from south of Ceylon at 4°N also were taken in a net that 

 had fished at 2000 m ; temperature and salinity values are the same as 

 for the Chagos specimen and the oxygen concentration is slightly 

 lower, 2.50 ml/L. Massy's shallowest specimen (870 m) was taken at a 

 temperature between 7°-8° C and a salinity between 34.90%o and 



