CEPHALOPODA. 



535 



along that canal, being gradually lost in its 

 inner membrane, the lamina next the gizzard 

 is peculiarly enlarged, so as evidently to pre- 

 sent an obstacle to the regurgitation of bile 

 towards the gizzard. The inner surface of the 

 rest of the intestinal canal presents a few lon- 

 gitudinal rugae, with slightly marked transverse 

 puckerings. 



In the Dibranchiate Cephalopods the gul- 

 let, in consequence of the position of the 

 stomach near the lower part of the visceral 

 sac, is of great length (a, a, Jig. 221), but 

 varies in this respect according to the form 

 of the animal. We have seen that in the 

 Nautilus it is dilated into a pyriform crop ; 

 a similar dilatation occurs in the genus Octo- 

 pus ; but its position is reversed, the larger end 

 of the sac being uppermost, and probably as 

 the result of the habitually reversed position of 

 the animal with the head downwards, the crop 

 is extended into a large cul-de-sac above the 

 part where the oesophagus opens into it (b, 

 Jig. 220). From this part the crop gradually 

 contracts to its termination. 



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, Jig. 221).* 



The stomach (c, figs. 220, 221,) 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 O3sophagus and crop (a', b', 

 fig. 220) acquires a greater thickness in the 

 gizzard, and is disposed in longitudinal rugse ; 

 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 some 

 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 



* From this difference I conclude that Aristotle 

 took his description of the digestive viscera of the 

 Malakia from the Sepia or Teuthis: he says, Mtra 

 Ji TO (TTOjUd ly^Qvriv oltri)<j>a.yov jUtntpov xai ff-rtvtv, 

 i^o/uivov Ji TOUTOU wptXo(3ov [tiycLV xai <f>8pi<pp? 

 opvifltiJa. " After the mouth they have a long and 

 narrow oesophagus, then a large round gizzard 

 similar to that of a bird." Hist, de Anim. lib. iv. 

 c. 1.9. But it is evident that he also had dissected 

 the Octopus, as he afterwards notices the difference 

 in the position of the ink-bag, which occurs in this 

 genus as compared with the Sepia. 



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 (/; figs. 220, 221). In each of these 



Fig. 221. 



Alimentary canal of the Sagittated Calamary.* 



genera its cavity is occupied by glandular 

 laminae (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, t, 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, i, 

 fig. 220), are the most conspicuous. The lon- 

 gitudinal rugae in the Scpioteuthis and Cala- 



* Home, Lectures on Comp. Anat. pi. Ixxxiii. 



