FISHERY BULLETIN: VOL. 80, NO. 4 



IV, 50.0-55.0-59.6). Arm IV is longest in both 

 sexes. The arms are nearly square in cross 

 section and they taper distally into fine delicate 

 tips. The keels of arms I and II are confined 

 mainly to the distal halves of the arms. The 

 swimming keel of arm III is as wide as the arm at 

 its midpoint. The lateral membrane (or tentacu- 

 lar sheath) of arm IV is moderately wide and 

 extends to the tip of the arm. Dorsal and ventral 

 protective membranes are present in all the 

 arms. The ventral membrane is more developed 

 than the dorsal, particularly on arm III. 



In the males the right arm IV is hectocotylized. 

 The ventral protective membrane on this arm 

 forms a very wide lappet that extends from about 

 the middle half, opposite the sixth pair of hooks, 

 to about four-fifths of the arm length. Distally 

 the membrane is much narrower and tapers to 

 the arm tip (Fig. 4F). The dorsal protective 

 membrane is slightly modified: a small tongue- 

 like flap is developed opposite the distal end of 

 the larger medial lappet. In addition, the males 

 have numerous conical tubercles at the bases of 

 the oral surface of all the arms and between the 

 bases of all the hooks. 



The biserial and regularly arranged hooks are 

 completely sheathed by membranes (Fig. 4B). 

 The distal arm suckers have long stalks. Each 

 inner ring has eight teeth on its distal half and 

 none on the smooth proximal half (Fig. 4C). The 

 outer rings bear pegs all around. The suckers are 

 progressively smaller distally; the distal suckers 

 assume a globular shape, have small apertures, 

 no teeth, and no outer rings. 



The tentacles are longer than the mantle (TLI 

 104. 9- .7 53.3-188.9) and are about twice the length 

 of the longest arm. The stalk is oblong in cross 

 section near the base, very muscular, and almost 

 as thick as arm III. The proximal partof the club 

 is as narrow as the stalk or only slightly ex- 

 panded. The club becomes unusually narrow in 

 the distal one-third (Fig. 4J). The tip is blunt. 

 The aboral keel is about one-half of the club 

 length. A semilunar membrane is present on the 

 ventral or oral side; it extends between the 

 carpal area and the fourth pair of hooks. Protec- 

 tive membranes are developed on the ventral 

 side but are rudimentary dorsally. Protective 

 membranes are absent on the dactylus. The 

 carpal cluster consists of three or four smooth- 

 ringed suckers and several rounded pads in a 

 compact round cluster together with some ir- 

 regular grooves and ridges. There are 13 or 14 

 robust hooks in two rows on the club. The ventral 



row includes a series of greatly enlarged hooks. 

 The hooks (Fig. 4D) are enclosed by membranes 

 but the tips are exposed. These hooks have very 

 broad bases and are set in rounded shallow ex- 

 cavations. Marginal suckers are absent. Twelve 

 to 18 transverse rows of 4 small suckers per row 

 occupy the narrow dactylus. About 12 of these 

 suckers at the tip are slightly larger than the im- 

 mediately preceding transverse row, thus 

 forming a cluster at the tip of the club. All the 

 club suckers have smooth inner rings (Fig. 4E). 

 The pegs on the outer ring are moderately long 

 and may hide the smooth edge of the inner ring 

 from view. 



The integumentary photophores occur in 

 different sizes ranging from about 0.2 to 0.4 mm. 

 A photophore may appear dark or very pale, 

 depending on the extent of pigmentation. Many 

 of the larger photophores are heavily pigmented, 

 except for a small central area. Most of the 

 smaller photophores are pale because pigmen- 

 tation is confined to the periphery in the form of a 

 very thin dark ring. Intermediate conditions be- 

 tween these extremes occur. At first glance the 

 photophores on the mantle appear scattered at 

 random, but on closer examination one can 

 recognize four multiserial, ill-defined rows: two 

 rows on each side of a very narrow midline space 

 that extends from the anterior opening of the 

 mantle to the tail and bounded laterally by a 

 broad zone of photophores (Fig. 4A). Each row 

 consists of large and small photophores set near 

 each other; smaller and whiter ones occupy the 

 central part of the row, while the larger and 

 more conspicuously darker ones are located 

 mostly on the outer area of the row. These rows 

 become more difficult to distinguish posteriorly. 

 A single row of evenly spaced photophores 

 extends along the lateral margins of the tail. 

 Numerous photophores occupy the ventrolater- 

 al surface and some single photophores, gener- 

 ally small ones, are scattered on the dorsal sur- 

 face of the mantle, except near the midline. The 

 edge of the mantle is lined by a single row of 

 photophores; the photophores are spaced pro- 

 gressively farther apart toward the dorsal mid- 

 line. 



The funnel has six groups of photophores: Two 

 rows separated by a midline space on the ventral 

 side; a short row on each lateral side; and two 

 dorsal rows, one on each side of the bridle. 



A small triangular cluster of photophores is 

 situated in the apex of the funnel groove. A space 

 in the ventral midline of the head is broken by a 



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