BATHYPELAGIC SQUID BATHYTEUTHIS 35 



branes of the foiirUi amis are very -weakly developeid along their 

 entire length. 



The oral surfaces of the arms are covered with numerous, small 

 suckers that are irregularly arranged in up to four longitudinal rows 

 particularly on the dorsal three pairs of arms (pi. 3a). One or two 

 suckers arise proximally close to the midline of the arm ; these may be 

 in a single row or slightly biserial. The next several pairs of suckers are 

 generally clearly distributed in two biserial, often well -separated rows. 

 It is difficult to determine exactly how many longitudinal sucker rows 

 exist, because a]x)ut a third to halfway out the arms the distribution 

 of suckers becomes irregular. Generally, however, the rows can be 

 separated down the midline of the arm where no suckers occur so 

 that on each side a band of biserially arranged, closely packed suckers 

 occurs that continues toward the tip. When the sucker stalks on each 

 side of the midline emerge from the oral surface of the arms they are 

 in biserial arrangement, but beneath the surface their bases arise nearly 

 in line. The sucker arrangement on the ventral arms usually remains 

 uncomplicated with a normal biserial distribution. Close to the arm 

 tips the suckers diminish in size and number. The sucker-bearing por- 

 tion of the arm terminates proximal to the extreme tip of the arm, 

 and the last traces of the protective membranes fuse in the middle; a 

 sudden decrease in the diameter of the arm occurs distal to this point. 

 The extreme tip of the arm may be entirely devoid of suckers, or one 

 or two minute suckers may be present (pi. 3c). In either case the tip 

 is short, almost blunt. 



The texture of the arms is the same as that of the head and mantle ; 

 the arms are covered with the reticulate integument and the subcu- 

 taneous gelatinous layer. 



The tentacles are extremely long, thin and muscular (pi. 1). They 

 range in length from about 100% to 130% of the mantle length. 

 (These values may vary considerably depending on the amount of 

 contraction at the time of fixation.) The tentacular stalks are nearly 

 round in cross section except along the flat to slightly concave oral 

 surface. The longitudinal concavity or depression extends nearly the 

 entire length of the tentacular stalk ; it is less pronounced toward the 

 base of the stalk. Occasionally a slightly raised ridge appears in the 

 depression, but this is a factor of contraction of muscles during fixation. 



The tentacular club is relatively short, narrow, and unexpanded 

 (pi. 4a) ; it belongs to the simple type and is not divided into distinct 

 regions of carpus, nianus, and dactylus. The club occupies from about 

 20% of the mantle length in younger specimens up to about 30% in 

 adults. The club length is about 20% of the tentacle length. The 

 tentacular stalk maintains about the same diameter along its entire 



