In the Argonaut the crop commences by a similar lateral dilatation, but is continued of almost uniform breadth to the stomach.
In the Sepia, Sepiola, Rossia, Onychoteuthis, Loligopsis, and Loligo, and probably in the other Decapods, there is no crop, the gullet being continued of uniform breadth to the stomach (a, a, fig. 221).14 The stomach (c, figs. 220, 224) in all the Dibranchiate Cephalopods is a more or less elongated sac, having its two orifices, the car dia (d) and pylorus (e), close together at the anterior or upper part of the sac, as in the gizzard of birds : the muscular fibres are simi larly disposed, and radiate from two opposite tendons ; they form a stratum of about the same thickness as in the stomachs of omnivo rous birds. The epithelium, which is con tinued from the cesophagus and crop (a' , b' , fig. 220) acquires a greater thickness in the gizzard, and is disposed in longitudinal rugm ; it is readily detached from the muscular tunic.
The intestine, at a short distance from the pylorus, communicates with a glandular and laminated sac, analogous to the pyloric ap pendages in Fish, but which in the Cephalo pods is always single.
In the Nautilus, we have shewn that this rudimental pancreas (p, fig. 219) is of a sim ple globular form, as in the Doris and sonae other Gasteropoda. It presents a similar form in Rossia and Loligopsis, in the latter of which it is of large size (g, fig. 223). In Argo nauta it is triangular; in some species of Loligo, as in the Loligo communis, it is ex tended into a long pyriform membranous bag, but in the Loligo sagittata, Sepia, and Octopus, it is elongated and twisted spirally, whence it is compared by Aristotle to the shell of a Whelk (f, figs. 220, 221). In each of these genera its cavity is occupied by glandular laminw (g, g) ; the biliary ducts terminate be tween two of the largest folds, which make a curve as they pass into the intestine, and are continued, gradually diminishing in size, along the canal, presenting at its commencement two tumid projections, which tend to prevent a regurgitation of bile towards the pylorus.
The intestine in the Nautilus makes a loop, or narrow fold upon itself before it is continued forwards to the base of the funnel. In the Octopus it is characterized by
a similar fold, but in the Cuttle-fish and Cala mary the gut is continued in a straight line from the stomach to the vent (i, i, fig. 221), and is consequently very short and simple : in both cases it maintains nearly a uniform diameter to its termination.
The internal tunic of the intestine is dis posed in longitudinal folds, of which the two at its commencement, above described (i, fig. 220), are the most conspicuous. The lon gitudinal rugm in the Sepioteuthis and Cala mary terminate abruptly where the duct of the ink-bag enters the gut (k, 221), which for the small extent beyond this part is smooth internally.
In the Octopods the intestine passes through the muscular septum of the branchial cham ber, immediately a.bove which it terminates. In the Decapods the rectum and duct of the ink-gland are surrounded by the muscular fibres which connect the pillars of the funnel to one another; in both cases the fibres serve as a sphincter to the anus.
In many Dibran chiata, especially the Decapods, the termi nation of the rectum is provided with two lateral fleshy appen dages ; for which, as far as we know, no use has hitherto been as signed. In the Sepio teuthis these process es (a, a, fig.222) are of a broad inequilate ral triangular form, attached to the sides of the transverse anal aperture (b) by their acute angle, from which a ridge extended lon gitudinally to the middle of the base ; when the processes were folded down upon the vent (as in A,fig.222), the ridge fitted into the aper ture, so as accurately to close it. In the Cuttle-fish the corresponding processes are of a rhomboidal form, with a thicker ridge on the side next the anal aperture, which they in like man ner are adapted to defend against the entrance of foreign substances by the funnel. In other genera they are not adapted to defend the anus mechanically, being elongated an'd filiform; but they probably serve to give warning of the presence of foreign bodies, and excite the necessary contraction of the constrictors of the gut ; Rathke compares them to antennaa in the Loligopsis, where the anal processes are very long (11,fig. 223).