

RESPIRATION AND DIGESTIVE APPARATUS. 341 



these vessels, when arrived at the base of the respiratory organs, 

 generally present remarkable dilatations (cb\ interwoven with 

 muscular fibres, so as to form two contractile reservoirs, perform- 

 ing the functions of pulmonary hearts. This arrangement is 

 observable in all CepTialopods with two gills ; but does not exist 

 in those which are provided with four. It may be regarded as 

 a transition-form between the heart of the lower Mollusca, which 

 is altogether systemic ( 946) ; and that of Fishes, which is en- 

 tirely respiratory ( 555). 



952. The digestive apparatus is very complicated. The 

 mouth is surrounded by a circular lip ; and the parrot-like jaws 

 are put in motion by powerful muscles. There are well-developed 

 salivary glands, several stomachs, and a voluminous liver ; the 

 intestine terminates in the branchial cavity, at the base of the 

 funnel by which the water is ejected, and communicates with a 

 very singular secreting organ, which, in the dibranchiate (two- 

 gilled) Cephalopods, produces an abundance of a black liquor, 

 commonly termed its ink. The 



duct of this gland opens near 

 the anus ; and, when the ani- 

 mal is in danger, it expels this 

 liquid through the funnel in 

 sufficient quantities to hide it 

 from the view of its enemies, by 

 mingling with the surrounding 

 water. It is the ink of one of 

 these animals, the Cuttle-fish, 

 which is employed in paint- 

 ing, under the name of Sepia ; 

 and several authors look upon 

 Indian Ink as an analogous sub- 

 stance. The four-gilledCephalo- 

 podspresentnothingofthiskind. 



953. The arrangement of the 

 organs of locomotion, which are 



fixed around the mouth, varies in different divisions. In the 

 two-gilled Cephalopods, there is a crown of large fleshy tenta- 

 cula, whose internal surface is provided with suckers, by means of 



VOL. II. 



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