CEPHALOPODA OP THE HAWAIIAN ISLANDS. 
283 
into practically a single row on the distal portion of the dorsal arms, contemporaneous with the general 
atrophy of the arm itself. The suckers of these arms are ultramarginal except as just noted, and the 
rows very widely spaced ; tlie suckers of the third arms are somewhat intermediate between this con- 
dition and that which prevails on the ventral pair. 
Male: Eody much smaller, perhaps half as large as that of the female, but quite as variable in shape 
(figure 10 shows the extreme of rotundity). Arms relatively shorter and more delicate than in the 
female; the four dorsal arms much less highly 
specialized, their tips normal, and the very 
delicate webbing not so well developed. Right 
ventro-lateral arm hectocotylized, the modifica- 
tion affecting the entire arm, which attains its 
development in a specialized sac occupying the 
region which would ordinarily be the base of the 
arm between the base of the funnel and the eye. 
(Cf. the account given by Steenstrup, 1857, p. 
103-105.) It is visible through the thin overly- 
ing integument even in very young specimens 
as a whitish vermiform body compactly coiled 
upon itself in such a fashion as to occupy as 
little space as possible. This arm undergoes a 
much more rapid growth than the rest of the 
animal, so that in males measuring about 3 cm. 
in length (station 4010) the sac is already vigor- 
ously crowding the eye and funnel and the ani- 
mal has consequently a somewhat lopsided ap- 
pearance ; at this stage also the sac has begun to 
bulge forth by the side of the mouth as a large 
rounded tumor-like protuberance. In the large 
mature male from station 4086, the arm had 
apparently just broken from its sac, but still re- 
mained attached by its basal end at the time of 
capture. At this stage the hectocotylized arm is a 
highly complex structure as long or longer than 
the animal itself. It differs very markedly from 
the hectocotylus of Argonauta and may be 
briefly described as follows: 
Much flattened; widest about a third of the 
way above the constricted and bluntly pointed 
base. Inner surface bearing about 46 pairs of 
closely placed suckers ranked in two rather 
widely interspaced marginal rows; outer surface 
ornamented with a conspicuous double fringe 
of long acutely conical papillae, which extend 
laterally just above the suckers along the proxi- 
mal two-thirds of the arm; when the distal 
third of the arm is reached, the papillae suddenly cease, the outer surface becoming much flattened, 
naked, and perfectly smooth. Between the rows of papillae the skin is minutely ridged and tuber- 
cled ; near the base an irregular series of small rounded tubercles along the median line gives way 
on the smooth part to a very fine longitudinal costation; on either side a flanking series of low roxmded 
transverse ridges persists along the entire papillate portion of the arm. The apparent differentiation 
of the arm into regions extends even to the suckers, the 27 pairs arming the papillate portion of the arm 
being very different from the remainder. Here the suckers are crowded, thickened, massive, elevated, 
Fig. 10. — Tremoctopus violaceus, lateral view of adult male, frcan 
station 4086, with nearly ripe hectocotylus [225], X 4. Drawn by 
R. L. Hudson. 
