. Elements of Comparative Anatomy. alime:^taky canal of ^iollusca. 363 mid-gufcj whicli is provided with a caecum; this iuuer wall thrown into longitudinal folds for the first part of its length. It generally takes a straight course (it is slightly coiled in Nautilus and the Octopoda only) forwardsj to a short hind-gut (Fig. 193, i), which opens to the exterior at the base of the funnel. In many Cephalopoda there are two or three valves or valvular processes around the anus, the muscles in which are remarkably well developed. The c£eca (Fig. 193, c) at the commence- ment of the mid-gut vary no
. Elements of Comparative Anatomy. alime:^taky canal of ^iollusca. 363 mid-gufcj whicli is provided with a caecum; this iuuer wall thrown into longitudinal folds for the first part of its length. It generally takes a straight course (it is slightly coiled in Nautilus and the Octopoda only) forwardsj to a short hind-gut (Fig. 193, i), which opens to the exterior at the base of the funnel. In many Cephalopoda there are two or three valves or valvular processes around the anus, the muscles in which are remarkably well developed. The c£eca (Fig. 193, c) at the commence- ment of the mid-gut vary not only in external form, but also in the characters of their in- ternal surface. The cascum is either rounded (Nautilus, Rossia, Loligopsis) or elongated; in the latter case it is often spirally coiled When the caecum is very coiled several times (e e). portion also has its (Sepia, Octopus), long, it is often The inner surface is either thrown into pro- cesses, which are arranged in a lamellar fashion (Nautilus), or these processes may form circular folds arranged in conformation with the sphal form of the cascum. Two of the largest folds receive the efferent ducts of the liver, and project so far into the lumen of the enteron as to form at times a valve-like apparatus which shuts off the CEecum. It is probable that this caecum has a secretory function, as in those forms (Loligo vulgaris) in which the folds are absent a large number found in its Fig. 193. Digestive appa- ratus of Loligo sagit- tata. oe ffisophagus. V The stomach, opened longitudinally. x A probe passed through pylorus, c Commence- ment of the ctecum. e e Its spiral portion. i Hind-gut. a Ink-bag. 6 Its opening into the rectum (after Home). of glands are to be Organs appended to the Enteric Canal. 1) Appendages of the fore-gut. § 280. Of those glandular organs which are connected with the enteric canal, the salivary are found only in those forms in which the pharynx is developed; it is possible therefo
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