THE CEPHALOPHORA. § 217. 
246 
§ 217. 
The Heart is wanting in only a few genera of the Cephalophora. Almost: 
always it has a pericardium,” and is divided into a simple, very muscular 
ventricle, and a thin-walled auricle which is equally simple, rarely double. 
The arterial blood passes from the respiratory organs into the auricle,. 
thence into the ventricle, from which it is forced through a very short aorta 
over the body. ‘These two chambers of the heart are usually pyriform, and 
are joined together at their large extremity by a constriction in which is. 
sometimes situated a valve, which prevents the return of the blood into the 
auricle. 
The position of the heart usually depends upon that of the respiratory 
organs. 
It is generally situated at the base of the branchiae, or in the 
bottom of the pulmonary cavity. It is most often found, therefore, upon 
the right side of the body. 
Von den dusser. Lebensbeding. d. weiss-und 
Kaltbliitigen Thiere. p. 72; Ehrenberg, Uner- 
kannte Struct. loc. cit. Tab. VI. fig. I. 1, II. 1 
(Arion and Paludina); and Erdl, De Hielicis 
algirae vasis sanguiferis. Diss. Monach. 1840, p. 
10. 
With Planorbis, the blood is red. With the 
Cephalophora in general, there is only a very 
small quantity of fibrine, at least there is only a 
trace in the blood of Helix ; it forms a kind of a 
web, scarcely visible, uniting the globules into mass- 
es and rows. The nuclei of these blood-globules 
become very distinct by the addition of acetic acid.* 
1 Forbes (Instit. 1843, p. 358), and Darwin (Ann. 
of, Nat. Hist. XIII. p. 3), have been unable to find 
a heart with Sagitia ; although D’Orbigny (Voy. 
dans l’Amer. mér., or Isis. 1839, p. 501) affirms 
that he has seen the movements of this organ in 
this enigmatical animal, and Darwin (loc. cit. 
p. 6) has perceived a pulsating organ at the 
anterior extremity of the embryos. The heart 
is wanting, according to Quatrefages (loc. cit. 
I.), in Zephyrina, Actaeon, and Amphorina ; 
and according to Kélliker, in Flabellina, Rho- 
dope, and Lissosoma. However, Souleyet 
(Comp. Rend. XX.1845, p.73) contradicts, very pos- 
itively, the assertions of Quatrefages, and assigns 
a heart to all the Apneusta. The difficulties in the 
study of these animals, from their non-transparency, 
are undoubtedly the cause of many of these contra-’ 
dictory statemtents. One should not, also, conclude 
as to the organization of the adults from the develop- 
ment of the embryos ; for it is very singular that 
the embryos of Actaeon are completely developed 
without a heart (Vogt, Comp. Rend. XXI. No. 14, 
XXII. No. 9, or Froriep’s neue Not. No. 795, 
* (§ 216, note 2.) Leydig (loc. cit.) describes 
the blood of Paludina as containing two forms of 
corpuscles ; one, round, which became granular 
nucleated cells after the action of acetic acid; 
the other provided on one side with processes 
which disappeared upon the action of acid; see 
loc. cit. p. 170, Taf. XII. fig. 47, 48, In this con- 
nection, see also for the blood-corpuscles of the 
Gasteropoda (Buccinum magnum) and their de- 
velopment, Wharton Jones, Philos. Trans. 1846, 
Part IT. p. 96, Pl. Il. fig. 1-7, of the Gasteropoda 
division. Jones also mentions the stellate form of 
the corpuscle (fig. 4). It would appear to me that 
this peculiarity is, after all, only a crenulation due 
and 820), while with the other Gasteropoda the 
heart appears very early in the embryonic de- 
velopment. According to Nordmann (loc. cit. p. 
93), the embryos of J'ergipes, which has a heart, 
are developed as those of Actaeon, thus showing 
that the absence of this organ in these last is only 
a delay of its appearance. 
Wilms (loc. cit. p. 11) has been also equally 
unable to find a heart with Sagitta. 
2 The pericardium is apparently wanting with 
the Apneusta, 
8 Chiton, Haliotis, Fissurella, and Emargi- 
nula have two lateral auricles; the last three of 
these Scutibranchia resemble moreover the La- 
mellibranchia in their heart being traversed by 
the rectum; see Cuvier, loc. cit.,and Meckel, 
Syst. d. vergleich. Anat. V. p. 115. . 
4 See Cuvier, loc. cit. Pl. I. fig. 2-4, II. fig. 15 
Carus, Erlauterungstafeln Hft. VI. Taf. IL. fig. & 
(Helix); and Van Beneden, Exerc. zoot. loc. cit. 
Pl. III. fig. 11 (Hyalea). 
Nordmann (oc. cit. p. 26, Tab. TI. fig. 4) 
found with Tergipes, the auriculo-ventricular val- 
vular apparatus replaced by a very movable valve 
situated between the ventricle and the bulb of the 
aorta. With Limax, and Arion, the valves are 
wholly wanting (T'reviranus, Beobacht. aus d. 
zoot. u. Phys. p. 40). 
5 The heart is situated on the right side of the 
back, with most of the Tectibranchia, with the 
dextral Pectinibranchz, and Pulmonata, and with 
all the Limacina; while it is on the opposite 
side with Ancylus, Haliotis, and all the sinistral 
Gasteropoda. That of Carinaria, Clio, Hyalea, 
and Cleodora, is upon the dorsal median line, a 
little to the left. t 
to an exosmotic passage of the cell-contents — leav- 
ing the cell-membrane thus deeply wrinkled, as 
may often be observed also with the blood of verte- 
brates. — Ep. 
¢ [§ 217, note 5.] With Firola, and Atlanta, 
the heart is situated near the posterior extremity 
of the body ; its auricle and ventricle are com- 
posed of interlaced, striated muscular fibres ; both 
the auriculo-ventricular and the aorto-ventricular 
orifices are valvular ; see Hualey, Ann. d. 8c. Nat. 
XIV. 1850, p. 193. 
See also, for the heart its positions and connec- 
tions, with the Lymnaeacea, De St. Simon, Jour 
de Conchol, 1852, IT. p. 118. — Ep. 
