214 
A. E. Yerrill — North American Cephalopods. 
or less mulitated at the tips, and several had thus lost a considerable 
portion of their length, so that it is quite probable that originally the 
sub-ventral arms (or third pair) were actually longer than the ventral 
ones. The circumference of the third pair of arms, when measured 
by me, was considerably greater than that of the ventral ones ; the 
former being 1P25 inches; the latter 10 inches. Hence I have 
inferred that the greatest circumference (17 inches), measured by Mr. 
Harvey, applies to the third pair of arms. 
The ventral arms have both outer angles bordered by a strong, 
thick marginal membrane, about an inch wide. The arms are all 
more or less trapezoidal in form, and taper to very slender tips. 
When examined by me they had already lost nearly all their suckers. 
A few remained near the base of one of the arms of the third pair. 
These were 25 mm (1 inch) in diameter, with the aperture 15‘5 mm ( 62 
inch) across ; the denticles on the outer border of the marginal ring 
were broad-triangular, acute, and strongly incurved, much larger 
than those on the inner margin. 
Of the detached suckers, I have been able to study, with care, 18 
specimens from the sessile arms. Part of these are represented only 
by the horny marginal rings. The three largest differ from the rest 
in having the denticles less incurved and more nearly alike all around 
the margin, those on the inner edge being only somewhat smaller 
and more slender than those on the outer margin, while the rings 
themselves are less oblique and eccentric. These may have come, 
perhaps, from the ventral arms, near the base. The other suckers all 
belong to one type, like those seen upon the third pair of arms, 
described above. They differ, however, very much in size, in the num- 
ber of denticles, and in the presence or absence of more or less perfect 
denticles on the inner margin, this, in the smaller ones, often being 
without any distinct denticles whatever; the horny rings are very 
oblique and the aperture eccentric. The diametex*s vary from 8 mm 
to 24 mm externally; the apertures from 3'5 mm to 20 mm . 
One of the most perfect of these suckers ( b ) is preserved in alcohol 
with the soft parts (Plate XVII, figs. 5, 6), and was sent to me from 
Newfoundland by Mr. Harvey. This has a greater external diam- 
eter of 22 mm ; diameter of aperture, 10 inm ; height of cup (outside), 
16 mm ; height at center, 15 mm , height near inner margin, at attachment 
of pedicel, 6 mm ; length of pedicel, 14 mm ; diameter of pedicel, l-5 mm . 
In a side-view the sucker is oblique and gibbous ; the lower surface is 
convex centrally, but has a deep notch or pit near the front mai’gin, 
in the bottom of which the slender but strong pedicel is attached, 
