202 A, FE. Verrill—North Aimerican Cephalopods. 
The terminal portion, bearing the suckers, is 762°" in length and 
expands gradually to the middle, where it is 11°4°™ to 12°7™ in eir- 
cumference (15°3° when fresh), and 3-9 to 4°1°™ across the inner face. 
The sucker-bearing portion may be divided into three parts. The first 
region occupies about 17°8°" (7 inches); here the arm is rounded-trique- 
tral, with margined lateral angles, and gradually increases up to the 
maximum size, the inner face being convex and bearing about forty 
irregularly scattered, small, flattened, saucer-shaped suckers, attached 
by very short pedicels, and so placed in depressions as to rise but little 
above the general surface. The larger ones are 5 to 6™™" in external 
diameter; 3"™ across aperture; 15°" high. The smaller ones have a 
diameter of 4°™; aperture 2°5""; height 1™". The horny ring (Plate 
XVIa, figs. 9, 9a) is circular, thin, and of about uniform breadth all 
around; the edge is smooth and even, slightly everted; just below the 
edge there is a groove all around; below this a prominent, rounded 
ridge surrounds the periphery, below which the lower edge is somewhat 
contracted. A thick, soft membrane surrounds the edge. These suckers 
are at first distantly scattered, but become more crowded, distally, 
forming six to eight irregular alternating rows, covering the whole 
width of the inner face, which becomes 471°" broad. Scattered among 
the suckers are about an equal number of low, broad, conical, smooth, 
callous verruce, or wart-like prominences, rising above the general 
surface, their central elevation corresponding in form and size to the 
apertures of the adjacent suckers. These, without doubt, are intended 
to furnish secure points of adhesion for the corresponding suckers of 
the opposite arm, so that, as in some other genera, these two arms 
can be fastened together at this wrist-like portion, and thus may 
be used unitedly. By this means they must become far more effi- 
cient organs for capturing their prey than if used separately. The 
absence of denticulations prevents the laceration of the creature’s 
own flesh, which the sharp teeth of the other suckers would produce, 
under pressure, and the verruce prevent the lateral slipping, to which 
unarmed suckers applied to a smooth surface would be liable. 
Between these smooth suckers and the rows of large ones there is a 
cluster of about a dozen small suckers, with sharply serrate margins, 
from 5 to 8™™ in diameter, attached by slender pedicels. They are 
arranged somewhat irregularly in four rows, those of the outer rows 
more oblique and corresponding in form with the larger marginal 
suckers. 
