760 CLASS XI II. 



two of them, but in many Cephalopoda and some Gasteropoda, as 

 in lanthina, there are four ; in this case the anterior pair is situated 

 very close to the mouth. 



The liver is much developed. A gall-bladder is not present in this 

 class, and the secretion of bile is not effected from venous but from 

 arterial blood. In Helix the liver is divided into four large lobes. 

 In Testacella the liver is double, one on each side, whilst there are 

 three of them in Onchidium Peronii, each with a distinct gall-duct ; 

 two of these ducts implant themselves in the oesophagus, so that 

 the bile may act upon the chyme as soon as it is in the stomach. 

 In many Cephalopods also the liver is formed of several lobes 

 distinct from each other. The colour is yellow-brown or, as in 

 Nautilus, dark wine-coloured red. The finer structure of the liver 

 consists of numerous blind branched follicles which are covered 

 internally by a stratum of bile-forming cells 1 . 



The urinary secretion is not wanting in Molluscs, although it 

 has not yet been determined in all of them what organ effects it. 

 JACOBSON first observed that in the calcareous sac of Helix and 

 Limax, which CuviEtt had named the mucus-secreting organ 2 , uric 

 acid is present, and that this part ought to be named the kidney of 

 Molluscs 3 . This organ is a sacciform cavity provided internally with 

 numerous folds or laminae which is situated near the heart and has 

 an efferent duct that terminates close to the respiratory aperture. 

 In the Ctenobranchiates, as Murex and JBuccinum, the same is 

 described as the organ which secretes the purple fluid, and the duct 

 opens into the branchial cavity. In the cephalopods the spongy 

 appendages of the venous stems are to be regarded as kidneys 4 . 



[In several families of this class it has been shewn that in 

 those molluscs which live in water, the urinary organ performs still 



1 Cotnp. J. FRANK De Hepate Molluscorum, Berolini, 1844, 8vo, T. F. G. SCHLEMM 

 (see above, p. 605), H. G. LINDNER Nonnulla de ffepate et Bile evertebratorum, Bero- 

 lini, 1844, 8vo, H. MECKEL in MUELLER'S Archiv, 1846, s. 9 12. 



2 Organe de la viscosite, see Ann. du Mus. vn. p. 165, PI. 8, figs. 2, 3, 4, h, i, 

 PI. 9, fig. 8, 6 b, fig. 10, c (Memoire sur les Moll. No. xi) ; M. LISTER described the 

 same organ under the name of viscus cinereum. Exercitat. anat. de Cochleis, Londini, 

 1694, Tab. i, fig. i, d. 



3 Journal de Physique, Tom. 91, p. 318, MECKEL'S Archiv, vi. 1820, pp. 370, 371 ; 

 Bidrag til B'oddyrenes Anatomie og Physiol., Kjobenhavn, 1828, pp. 24 28. 



4 See the full account of observations and opinions relating to this subject in 

 V. SIEBOLD Lehrb. der vergl. Anat. s. 391 401. 



