38 U.S. NATIONAL MUSEUM BULLETIN 291 



rings have 12 teeth and the medium-sized rings have 9-10. The teeth 

 are always small; they are more elongate and truncate in the distal 

 portion of the ring and shorter, more rounded, and knoblike proxi- 

 mally. The teeth on the larger rings often are separated at their bases 

 by the widths of several teeth ; teeth are widely spaced on the smaller 

 rmgs. The rings from the first anns of a specimen of 28 mm mantle 

 length bear eight teeth: four long, truncate, widely spaced teeth 

 distally and four small, round, widely set knobs proximally (pi. 4d). 

 These rings measure 0.12 to 0.14 mm in diameter. 



Tlie outer ring has 3 to 4 concentric rows of chitinous knobs that 

 become elongate and toothlike on the inner row. The outer ring fits 

 closely around the aperture of the inner ring; in this position the inner 

 row of toothlike knobs serves as an additional row of teeth that are 

 very closely associated with the teeth of the inner ring. 



On the second arms the outer rings measure 0.24 mm and the inner 

 rings 0.14 mm (pi. 4e). There are 9 to 10 teeth around the aperture. 

 The teeth are generally short, truncate to rounded in shape; some are 

 worn so that the tips are concave. 



The largest suckers on arm III have outer rings 0.24 mm in 

 diameter and inner rings 0.16 mm in diameter. The larger inner rings 

 bear about 12 evenly spaced teeth (pi. 4f), while the smaller rings have 

 8 teeth that are more elongate and widely spaced than those of the 

 larger rings. 



The diameter of the outer ring of the largest sucker on the fourth 

 arm is 0.28 mm and of the inner ring 0.20 mm. On the largest inner 

 rings appear 12 to 14 small, widely spaced truncate to rounded teeth 

 (pi. 4g) ; 9 teeth appear on the medium-sized rings where the 3 to 4 

 distalmost teeth tend to be more elongate than the others. 



The suckers on the buccal lappets possess outer rings that measure 

 0.18 mm in diameter and inner ring apertures that measure 0.12 mm 

 across. The 9 to 10 teeth on the inner ring are widely spaced and 

 elongate, particularly along the distal border (pi. 4i). 



The buccal membrane is large, fleshy, and rugose (pi. 3a). The 

 buccal connectives are attached to the dorsal, dorsal, ventral, dorsal 

 oral edges of arms I-IV respectively (pi. 3b). The buccal lappets 

 bear from to 3 minute suckers that have 8-12 teeth on the chitinous 

 rings (pi. 4i). The significant geographical variation that occurs in 

 the number of buccal suckers is discussed in detail later. 



The buccal mass, comprised of the muscular bulb that encases the 

 mandibles, radula, and other mouth parts, is relatively smaller in B. 

 abyssicola than in other oegopsids (e.g., ommastrephids, enoploteu- 

 thids, gonatids). The beaks (pis. 3d, e) are small; they are darkly 

 pigmented where the rostra are exposed, but the pigmentation light- 



