176 U.S. NATIONAL MUSEUM BULLETIN 291 



depths the captures were made farther from the bottom, which in- 

 dicates that this species inhabits a particular zone in the sea in reha- 

 tion to the surface and not to the bottom. 



The points along the left and upper edges of the scatter diagram 

 beginning at 500 m above the bottom and 3000 m depth represent 

 the maximum depths of capture for B. ahyssicola. The points on the 

 right, and lower edges of the scattergram represent shallowest cap- 

 tures. Most captures were made in water between 3000 and 5000 m 

 deep, and most ranged from 1400 to 3800 m above the bottom. 



Only one capture occurred where the bottom was less than 2500 m 

 deep : the tow^ was made 1100 m above the bottom at a bottom depth 

 of 1650 m along the edge of the Peru Current off southern Chile. The 

 bottom descends veiy steeply in that area, and possibly the capture 

 was made over deeper water a short distance from the point of the 

 sounding or the specimen was carried inshore by currents. 



Two factors must be considered. Because of the possibility of the 

 midwater trawl fouling, it is generally not set to fish close to the bottom, 

 so the indication that B. ahyssicola does not often occur closer than 

 about 1000 m from the bottom may merely be a reflection of cautious 

 trawling techniques. In addition, tows deeper than 3000 m are rare 

 from the Eltanin because they require such a long time to complete. 



The chart of geographical distribution of BathyteufMs (fig. 50) 

 shows that captures are generally made well offshore over deep water. 

 Captures that are plotted relatively close to shore are in areas where 

 the bottom drops off steeply, e.g., along the western coasts of con- 

 tinents (South and Central America, West Africa, Southern Cali- 

 fornia). If B. ahyssicola is found inshore in shallow water it is 

 probably because currents have swept it out of its normal deep habitat. 

 This is undoubtedly the case with the single specimens taken by the 

 Pelican II and the Silver Bay in the northern Straits of Florida. In 

 regard to the Straits of Florida another possibility exists. Some evi- 

 dence indicates that specimens of normally deep-living species in the 

 Caribbean and Atlantic are forced up into the relatively shallower 

 water over the 800 m sill between Florida and the Bahama Banks. 



In any case, B. ahyssicola nonnally is not associated with the bottom 

 in any direct way. 



Aspects of Regional Distribution and Relative Abundance 



1. Regional Occurrence 



Bathyteuthis abyssicola is common througliout the Antarctic, but is 

 not equally abundant in all areas. Furthermore, within particular areas 

 its abundance is dependent upon its proximity to the Antarctic Con- 

 vergence Zone. Table XII gives a breakdown of successful tows and 



