CEPHAUOPODS OF WESTERN NORTH AMERICA. 29I 



or keels present along the outer surfaces of all the arms in some specimens, but prominent only on the 

 third pair. Suckers spherical, oblique; in two rows at the base and tip of all the arms, but in the adult 

 often extremely crowded along the middle, where they are apparently ranked in three to four rows; 

 indications of this condition always present, at least in fully gro«-n individuals, but in a few specimens 

 (notably a female from Albatross station 4457) the two-rowed condition persists over all except a very 

 small portion of the arm; sucker openings circular, minute; homy rings well developed, with entire 

 margins. 



The detailed structure of the arms in the two sexes differs greatly. In the female, the arrange- 

 ment of the suckers on none of the arms is essentially unlike that on the others, and suckers occupying 

 analogous poskions in the different rows differ very little, if any, in form or size. The males present 

 a greatly modified condition. Here both dorsal arms are hectocotylized; strongly recurved, their 

 suckers greatly reduced; the latter usually in two rows" until just before the tip is reached, when 

 they become increased to four for a small space, then reduced to two again at the extremity; bases of 

 the sucker pedicels (especially those of the outer row) much enlarged and transversely compressed to 

 form a prominent series of transverse folds or ridges very similar to those already described by Steen- 

 strup and others as obtaining in R. macrosoma (pi. XLin, fig. 2). There is a narrow marginal membrane 

 on the inner side of these arms and a much wider and more prominent one along the outer margin. 

 Above the latter and constructed parallel with it so as to form a deep fossa is a second membrane extend- 

 ing distally from the base of the arms for more than half their length (pi. XLiri, fig. 3). The suckersof 

 the remaining arms are much enlarged, but otherwise much as in the female; those of the second and 

 third pairs best developed and most densely placed; largest at the middle of the arm, gradually decreas- 

 ing in size toward the tips, but subequal in all the rows at the same point on the arm (pi. XLUi, fig. 2). 

 In young males the suckers are two-rowed and very irregularly unequal in size. 



Tentacles variable; sometimes longer than the body, but often completely retracted; stout, the 

 inner surfaces flattened and with a distinct median groove. Tentacular club elongate, but little 

 expanded; the sucker bearing area bordered by a narrow marginal membrane, outside of which dorsally 

 and parallel is a second much larger and wider membrane, the latter when expanded nearly half as 

 wide as the club itself (pi. XLiii, fig. 4). Suckers small, unequal; largest dorsally at the base, thence 

 gradually decreasing in size ventrally and toward the tip; in but two to three rows at the extreme 

 base, but thence multiplying to as many as seven or eight near the middle; cup-shaped, with wide 

 apertures, moderately long peduncles, and homy rings furnished with numerous small blunt teeth. 



Gladius slender, lanceolate, shorter than the mantle, very thin and delicate posteriorly. 



Skin everywhere smooth, without papillae, although some specimens show a number of definite 

 but more or less obscure grooves or plicae rimning longitudinally on the dorsal surface of the mantle. 



Color in life unknown; in alcohol reduced to the usual brownish buff, heavily punctate above 

 and in less degree below with purplish chromatophores, which extend even over the fins, though fewer 

 on their under surfaces and margins. 



The more important measurements of twelve specimens of both sexes are given in the appended 

 table. 



(1 In a few specimens (station 4377) the four-rowed condition extends over the greater portion of the arm. 



