BATHYPELAGIC SQUID BATHYTEUTHIS 79 



In addition, the largest specimens of abyssicol^i (49-75 mm), the 

 largest of which is two times longer in mantle length than ih& largest. 

 hac'idifera.^ do not approach the largest known hacidlfera in range or 

 average of suckers; the equivalent number of suckers would be found 

 in specimens of hacldifera one-half to one-third the size of the largest 

 abyssicola from the Antarctic. 



3. Bathyteuthis terryi 



B. he7Tyi was discovered after the above analysis was completed. 

 The suckers on the arms of this species far outnumber those of abyssi- 

 cola and hacidifera. The following figures for herryi can be compared 

 wnth those in Table V: 



ML, millimeters Arm No. of suckers 



12 I-III 62-75 



IV 48 



23 I-III 175-185 



IV 110 



49 I-III 275 



IV 150 



Gill Size 



A conspicuous difference in the size of the gills is apparent between 

 abyssicol-a from the Antarctic and hacidifera. B. abyssicola has small 

 gills while hacidifera has larger, more voluminous gills. A character 

 such as gill size, however, may be a phenotypic expression of environ- 

 mental conditions rather than a genotypic difference. Antarctic and 

 eastern Pacific equatorial waters differ considerably in environmental 

 conditions, particularly in oxygen content, which in this context would 

 probably most influence gill size. The oxygen content of eastern Pacific 

 equatorial waters is significantly lower than that of Antarctic waters. 

 In an attempt to evaluate the extent and signficance of the differences 

 observed between hacidifera and Antarctic abyssicola., it is necessary to 

 examine the gill dimensions of specimens of ahyssi^ol/j, from the same 

 locality as hacidifei^a and from localities other than the Antarctic and 

 the eastern Pacific. Although the sample sizes are not large for the 

 Atlantic and eastern Pacific populations of Bathyteuthis., they do pre- 

 sent some interesting trends. 



Size of the gills may be determined by length, width, volume, and 

 number of gill filaments. In the current study gill volume has been 

 omitted. 



1. Gill filaments 



The number of gill filaments for specimens of hacidifera and of 

 ahyssicola from the Antarctic, Atlantic, and eastern Pacific is plotted 

 against mantle length in figure 18. The plot for ahyssicola shows an 



