14 



eve (r. r. pi. 1.)- These, however, are of a different structure from the preceding, 

 having at first sight the same finely annulated character, but with the circular 

 indentations extending on one side much deeper into the substance of the ten- 

 tacle, so that it is in reality composed of a number of flattened circular disks 

 appended to a lateral stem. The eyes {s. pi. 1 ; ^. pi. 2 ; o. pi. 7.) are about the 

 size of hazel-nuts ; they are not contained in orbits, but are attached each by a 

 short pedicle to the parietes of the sheath behind the digitations, and imme- 

 diately beneath the margin of the hood. 



Although the external configuration of the oral sheath is thus varied, its in- 

 ternal surface {I. pi. 2 ; /. pi. 4.) is uniform and smooth, except at the lower 

 part near the anterior margin, where there are two clusters of soft conical pa- 

 pillae, and on each side of these a group of laminae disposed longitudinally. 

 The smooth part is lined by a fine membrane, and is lubricated by a sapo- 

 naceous substance, evidently to facilitate the motions of the mouth and its 

 appendages. 



In order to examine these parts, the cavity into which they were retracted 

 was laid open by making a longitudinal incision along the middle surface of the 

 hood. Upon separating the cut surfaces, the parts more immediately investing 

 the mouth were brought into view, but the mouth itself was still concealed. 

 (See fig. 1. pi. 2, which exhibits the appearance of the parts in this stage of the 

 examination.) It was surrounded by tentacles of the same structure, but ap- 

 parently even more numerous than those which had been noticed on the ex- 

 ternal part of the head ; and on separating these, the organs of mastication w^re 

 found to be composed, as in the Cuttle-fish, of two strong hooked mandibles 

 [n. 0. pi. 4.) playing vertically upon each other, and surrounded by a fringed 

 circular lip (m. pi. 4.). 



External to this lip there are four broad flattened processes arising from the 

 inner surface of the sheath, of which two are superior, posterior, and external 

 (o. 0. pi. 2; g. g. pi. 4.) ; two inferior, anterior, and more immediately embracing 

 the mouth (p. p. pi. 2 ; i. i. pi. 4.) ; but the latter are connected on the ventral 

 aspect by a middle part (q. pi. 3 ; I. pi. 4.), convex exteriorly, and composed of 

 numerous laminae disposed horizontally, and projecting internally. Each of these 

 four processes (which may be termed labial) is pierced by twelve canals, the 

 orifices of which are disposed in a single, but rather irregular series along the 



