202 A. E. VerriU — JVorth American Cephalo^^ods. 



The terminal portion, bearing the suckers, is '76"2"" in length and 

 expands gradually to the middle, where it is 11'4'°^ to 12'7'^^"' in cir- 

 cumference (IS'S'^^'" when fresh), and 3*9 to 4*1^"' across the inner face. 

 The suckei'-bearing portion may be divided into three parts. The first 

 region occupies about I'/'S'^"' (7 inches) ; here the arm is roxincled-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; 1"5'"'" high. The smaller ones have a 

 diameter of 4""" ; ai)erture 2-5"'"' ; height 1""'". The horny ring (Plate 

 XYIa, 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 4-1"" broad. Scattei'ed among 

 the suckei's are about an equal number of low, broad, conical, smooth, 

 callous verructe, 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 Avrist-like portion, and thus may 

 be used unitedly. By this means they must become far more efli- 

 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 verrucas 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 witli the larger marginal 

 suckers. 



