. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 536 CEPHALOPODA. Fig. 222. mary terminate abruptly where the duct of the ink-bag enters the gut (k, fg. 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 above 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 Dibr
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 536 CEPHALOPODA. Fig. 222. mary terminate abruptly where the duct of the ink-bag enters the gut (k, fg. 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 above 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, ) are of a broad inequilate- ral triangular form, attached to the sides of the transverse anal. Anal valves, Sepioteuthis. aperture (i) 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 J,v/?),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 and 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 antennae in the Loligopsis, where the anal processes are very long (11 f Jig. 223). The apparatus for secreting the inky fluid, formerly regarded as characteristic of the class of Cephalopoda, is wanting in the Nautilus, which, as it has a large and strong shell to pro- tect its body,
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