CErilALOPODA. 



623 



227 



Katctilus ; but in Sepia and Loligo {fig. 226, i) it is continued for- 

 wards in a straight line, from the stomach to the vent. Its internal 

 membrane is longitudinally folded, but is smooth at the short tract 

 beyond the entry of the duct of the ink-bag (Ji) ; its termination is 

 constricted either by the muscular fibres of the branchial septum, or 

 by those which connect together the pillars of the funnel. In most 

 Decapods provided with fins for swimming forwards, the anus can 

 be closed by rhomboidal {Sepia) or triangular fleshy valves {Sepio- 

 tcuthis) : in Loligopsis these are modified into the form of antennal 

 filaments. There is no ciliated epithelium in the intestinal canal of 

 the Cephalopods. 



The liver {fig. 227, x) is of large size in the Dibranchiates, but of 

 more simple form than in Nautilun. It is usually of a reddish yellow 

 colour. In Sepia it is divided 

 into two lateral lobes, which are 

 notched at the upper extremity ; in 

 Onychoteuthis it is a simple, elon- 

 gated, compressed lobe with un- 

 divided extremities : in Octopus it 

 forms a single oval mass, flattened 

 anteriorly : in Eledone it is spherical, 

 corresponding with the ventricose 

 visceral sac. In the two latter 

 genera the ink-bag {d) is enclosed 

 within the capsule of the liver, and 

 was mistaken for the gall-bladder 

 by some of the early anatomists of 

 these Mollusks ; but in the Argo- 

 naut and the Decapods it manifests 

 its distinct function by its sepa- 

 rate position. The liver is sur- Octopus, 

 rounded by a smooth capsule, and is not subdivided externally 

 into lobules, as in the Nautilus and lower Mollusca. The biliary 

 ducts in the Octopods are simple canals which unite and terminate 

 by a common orifice in the pancreatic sac. In the Decapods tliey 

 receive the ducts of numerous clusters of csecal appendages beyond 

 the smooth part of the liver, which may perform a function analogous 

 to the pancreas.* 



The ink-bag consists of tough white fibrous texture, the outer sur- 

 face of wliich is coated by a thin silvery or nacreous layer ; its inner 

 surface presents a fine spongy glandular texture. It is usually of an 



* rrep. No. 775. X., vol. i. p. 229., & CCCLXXX. pi. 41, L. 



