338 MOLLUSCA. 



A fleshy funnel placed at the aperture of the sac, before the neck, affords an outlet 

 to the excretions. 



The Cephalopodes have two branchiae, one on each side of the sac, in the shape of a 

 compound fern-leaf. The great vena cava, when between them, divides into two. 

 branches, which terminate each in a fleshy ventricle, placed at the base of its respective 

 branchia, and propelling the blood into it. 



The two branchial veins tend to and terminate in a third ventricle, situated near the 

 bottom of the sac, whence the blood is carried to every part of the body by different 

 arteries. 



Respiration is effected by the water which enters into the sac, and is driven out 

 again through the funnel. It appears that the water even penetrates into two cavities 

 of the peritoneum, which the venae cavae cross in their course to the branchiae ; and 

 that it has some influence on the venous blood, through the medium of a glandular 

 apparatus attached to these veins. 



The mouth opens amidst the bases of the feet. It has two powerful corneous jaws, 

 similar to the beak of a Parrot, and between the jaws is a tongue roughened with 

 horny prickles. The gullet swells out into a crop, and then passes into a gizzard as 

 fleshy as that of a bird, to which succeeds a third membranous and spiral stomach, 

 into which the liver, which is very large, pours its bile through two conduits. The 

 intestine is simple and short. The rectum opens into the funnel. 



These animals have a peculiar excretion of a deep black colour, which they use to 

 taint the water when concealment is necessary. It is secreted by a gland, and reserved 

 in a sac, differently situated in different species. 



Their brain, inclosed in a cartilaginous cavity of the head, sends off from each side 

 a cord which swells, within each orbit, into a large ganglion, whence are derived innu- 

 merable optic filaments. The eye is formed of numerous membranes, and is covered 

 by the skin, which becomes transparent in passing over it, and sometimes forms folds 

 that supply the want of eyelids. The ear is merely a little cavity excavated on each 

 side near the brain, without semicircular canals or external passages, and in which 

 there is suspended a membranous sac, containing a little stone. 



The skin of these animals, particularly of the Octopus, changes colour, in patches 

 and in spots, with a rapidity greatly superior to that of the Chameleon.* 



The sexes are separate. The ovary of the female is at the bottom of the sac. Two 

 oviducts carry the eggs from it, passing them through two large glands which envelope 

 them, during their passage, with a viscous fluid, and gather them together into a sort 

 of cluster. The testicle of the male, similar in position to the ovary, gives off a vas 

 deferens that terminates in a fleshy penis situated to the left of the anus. A vesicula 

 seminalis, and a prostate, also open there. There is reason to believe that impreg- 

 nation is effected by a sprinkling of the seminal fluid over the eggs, as illustrated 

 in the majority of Fishes. In the season of spawning, the vesicula contains a vast 

 number of little filiform bodies, which, through a peculiar mechanism, writhe and 

 move about rapidly as soon as they fall into the water, and shed the fluid with which 

 they are filled. 



Tnese animuis are voracious and savage ; and as they are agile, and are furnished 



• See Cams, Nov Act. Nat. Cur. xii. part i. p. 320 ; and Sangiovanni, Ann. del Sri. Nut. vol. xvi. p. 30S. I' Also Coldstream, in Edinburgh 

 Joum. of Nil. and Geogrnph. Science, vol. ii. p. 296.] 



