760 CLASS XIII. 
two of them, but in many Cephalopods and some Gasteropods, as 
in Janthina, 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 TZestacella 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 cesophagus, 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’. 
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 Cuvter had named the mucus-secreting organ*, uric 
acid is present, and that this part ought to be named the kidney of 
Molluses’. This organ is a sacciform cavity provided internally with 
numerous folds or lamin which is situated near the heart and has 
an efferent duct that terminates close to the respiratory aperture. 
In the Ctenobranchiates, as Murex and Buccinum, 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’. 
[In several families of this class it has been shewn that in 
those molluses which live in water, the uriary organ performs still 
1 Comp. J. FRanK De Hepate Molluscorum, Berolini, 1844, 8vo, T. F. G. ScHLEMM 
(see above, p. 605), H. G. Linpner Nonnulla de Hepate et Bile evertebratorum, Bero- 
lini, 1844, 8vo, H. MecKEL in MuELLER’s Archiv, 1846, s. g—12. 
2 Organe de la viscosité, see Ann. du Mus. vu. p. 165, Pl. 8, figs. 2, 3, 4, h, %, 
Pl. 9, fig. 8, 6 b, fig. 10, ¢ (Mémoire sur les Moll. No. x1); M. Lister described the 
same organ under the name of viscus cinereum. Exercitat. anat. de Cochleis, Londini, 
1694, Tab. 1, fig. 1, d. 
3 Journal de Physique, Tom. 91, p. 318, MucKkEL’s Archiv, VI. 1820, pp. 379, 371 ; 
Bidrag til Béddyrenes Anatomie og Physiol., Kjsbenhayn, 1828, pp. 24—28. 
4 See the full account of observations and opinions relating to this subject in 
V. Sresoup Lehrb. der vergl. Anat. 8. 391—40l. 
