72 U.S. NATIONAL MUSEUM BULLETIN 234 



squarish in cross-section, somewhat rounded on the dorsal angle, but 

 slightly keeled on the ventral edge. Ill is compressed and bears a 

 broad keel, widest at about the middle of the keel. IV has a natatory 

 membrane dorsaUy and a low keel ventraUy. The suckers are biserial 

 and are bordered on each side by a trabeculate protective membrane. 

 There is a strong sexual dimorphism in the suckers of the males and 

 females. In the females the suckers of all arms are similar in their 

 dentition and not strikingly different in size. The larger suckers of 

 III have rings which are smooth on the proximal half but bear about 

 seven teeth on the distal half, the central one broad and pointed, the 

 marginal ones broad and square ended. In the males the suckers of 

 I and IV are similar to those of the females but bear usually only 

 six teeth on the distal half. The suckers of II and III are greatly 

 enlarged, however, larger than the largest suckers of the tentacular 

 clubs. The first two or three pairs basally have normal dentition, 

 followed by the enlarged suckers. In these there is a low, broad 

 truncate tooth proximally, aU that is left of the broad proximal smooth 

 area in the normal suckers, followed by 11 long square truncate teeth 

 around the entire ring, the central one slightly more slender and 

 pointed or rounded. 



The left ventral arm is hectocotylized in the male. Less than half 

 of the arm length, basally, is equipped with normal suckers. Beyond 

 this the suckers abruptly give way to a double row of papillae, fat 

 basally, attenuate distally, many of them with minute ringless suckers 

 on their tips. The papillae of the ventral row are nearly twice as 

 large as those of the dorsal row, the two rows spread outward and 

 separated by a low median ridge. 



The tentacles are long and stout, flattened, with a low keel on the 

 aboral surface which becomes expanded along the outer surface of the 

 club. Orally the stalk is ridged basally, but in the distal half becomes 

 flattened along a narrow strip, the sides of which form the trabeculate 

 protective membrane on each side of the club. The suckers of the 

 club are quadriserial, those of the hand portion large, those of the 

 slender distal portion small. On the hand the suckers of the inner 

 rows are about 1.5 times larger in diameter than those of the outer 

 rows. The large suckers bear 14 to 17 short sharp teeth on the 

 circumference of the horny ring. 



The buccal membrane is seven-pointed, each point bearing two 

 to five small suckers crowded at the tip. In the female there were 

 numerous spermatophores attached to the spermatic pad on the 

 ventral surface of the buccal membrane below the mouth. 



The ink sac bears a large oval light organ buried on each side. 

 VentraUy it appears as a fleshy bulge; there is a small round organ 

 within the sac. 



