S$ 216. THE CEPHALOPHORA. 245 
2, With the other Cephalophora, the liver is wholly isolated, nearly always 
_ asymmetrical,” and often divided into several lobes of a yellowish-brown 
or brownish-green color; often, also, it wholly envelops the intestinal con- 
volutions. The biliary canals, which arise from the hepatic lobes, form 
usually, two, three, or more excretory ducts, which empty the bile into the 
stomach or intestine, rarely into the oesophagus. © 
CHAPTER VI. 
CIRCULATORY SYSTEM. 
§ 216. 
For a long time it was erroneously supposed that the circulatory system 
of the Cephalophora was completely closed. But the heart or central portion 
of this system, is developed in an inverse ratio to the imperfect peripheric 
part which is without a capillary net-work. This incompleteness is often 
so great that, in many genera, the arteries are wanting and the veins more 
or less wholly absent. The circulation is, therefore, extravascular for a 
longer or shorter course, and passes into cavities (Lacwnae) situated in 
the parenchyma of the body.” 
The blood is colorless, often opalescent, and always very poor in corpus- 
cles, 
granular, indistinct nucleus. 
7 With Dentalium, there are two symmetrical 
livers, one on each side of the intestinal canal; see 
Deshayes, loc. cit. Pl. XV. fig. 11, or Isis. Taf. VI. 
fig.16,m.m. With Diphyllidia, also, there are 
two livers, one on each side of the stomach into 
which they open by several transverse excretory 
canals ; see Meckel’s Arch. 1826, p.15, Taf. I. 
8 For the external form of the liver, consult Cu- 
vier, loc. cit. The hepatic ducts open, near the 
pyloric orifice, with Limax, Helix, Testacelia, 
Doridium, and Dentalium ; into the intestine, with 
Haliotis, Vermetus, Pleurobranchus, Diphylli- 
dia, Doris, Planorbis, and Lymnaeus ; into the 
third stomach, with Aplysia, Dolabella, and Notar- 
chus; while with Onchidium, two of the ducts open 
into the cesophagus, and the third into the first 
stomach.* 
1 The tenacity with which the opinion was enter- 
tained that there is a completely-closed vascular 
system with the Mollusca, is shown in the fact that 
Cuvier (Régne anim. I. p. 50), after having seen, 
* [§ 215, note 8.] For the details of the hepatic 
structure with the Nudibranchia, see Alder and 
Hancock, \oc. cit. Part Il. Pl. Il. fig. 2, e. bh., 
and fig. 3 (Dendronotus) ; Part III. Pl. VIII. fig. 
9 (4eolis); Part IV. Pl. V. fig. 1, g. g. g. (Seyl- 
daea), and fig. 8, g g. (Eumenis); Part V. Pl. I. 
fig. 2,d.d., and Pl IL. fig. 1, f. (Doris). 
21* 
These last are also colorless and consist of smooth cells, with a 
with Aplysia, the veins communicate distinctly 
with the cavity of the body by special orifices, still 
persisted in the old view, — regarding this as an 
exception ; see Mém. loc. cit. p. 13. It is only 
latterly that the circulation of the blood through 
the lacunae and interstices “of the body, has been 
shown to be the rule, by Pouchet (Recherches loc. 
cit. p. 13), Milne Edwards and Valenciennes 
(Compt. rend. XX. 1845, p. 261, 750, or Froriep’s 
neue Not. XXXIV. p. 81, 257). 
Miine Edwards, in his memoir already cited 
upon the circulation of Pate/la, Haliotis, Heliz, 
Aplysia, Thetis, and Triton, has abundantly 
shown that the vascular system of the Cephalo- 
phora is also incomplete, and that the aorta termi- 
nates in a large lacunal sinus containing the brain, 
the salivary glands, the cesophagus with its mus- 
cles, and the retracted tongue, and which forms also 
a part of the visceral cavity ; see Ann. d. Sc. Nat. 
VIIL. 1847, p. 37, Pl. I.-III., or Schleiden and 
Froriep’s Not. V. p. 1, fig. 1—4. 
2 For the blood of the Gasteropoda, see Carus, 
For the liver of Chiton, see Middendorf (Bei- 
trage zur einen Malacozoologia rossica, St. Peters- 
burg, 1847, p. 63, Taf. V. fig. 2,1.). Its ducts open 
‘into the alimentary canal near the stomach. — Ep. 
