$ 252. THE CEPHALOPODA. 289 
the stomach, the small intestine, the rectum, the branchiae, and the genitak 
ome ; the artery of these last, however, sometimes arises directly from the 
eart. 
Nothing positive can now be said as. to the terminal relations of these 
arteries ; — that is, whether they are directly continuous with the venous. 
radicles by means of a capillary system with proper walls, or whether they 
terminate by orifices so that the blood is effused immediately into the paren- 
chyma of the body. 
The Venous system begins in the different parts of the body by numer- 
ous small vessels, of which we are still ignorant whether they are continu- 
ous with the terminal arterioles, or whether they commence by themselves. 
with proper orifices. Their radicles unite and form longer branches which 
finally open into a large Sinus. One of these sinuses, which is of a circular 
form, surrounds the upper extremity of the cesophagus, and receives the 
veins coming from the eyes, the arms,” and the parts of the mouth. From 
this sinus arises another, of an oblong form, which, since it extends into 
the cavity of the body and receives the different veins from the viscera. 
may be called a Vena cava superior. In the centre of the body it divides 
into two large venae cavae which extend on each side to the base of the 
branchiae® and terminate in the two so-called branchial hearts. These 
two veins receive, also, two trunks, which bring the blood from the mantle 
and are often dilated into two large sinuses.” ; 
The distinct, but often very thin walls of the venous sinuses, are some- 
times so intimately blended with the adjacent organs, that these sinuses may 
be easily taken for wall-less lacunae." 
6 Milne Edwards and Valenciennes (loc. cit.) 
throw no light on these questions. It is moreover 
singular that in the numerous and often very de- 
tailed figures of Delle Chiaje of the vascular sys- 
tem of Cephalopoda, he has nowhere represented 
in the least a capillary net-work between the arte- 
ries and veins; while Kédliker (Entwick. der Ce- 
phal. p. 81), declares that he has seen numerous 
oapillary vessels in the embryos of Sepia. 
7 All the arms of the Cephalopoda have two 
venous trunks. Lebert and Robin (Miller's. 
Arch. 1846, p. 130) have observed, in the venous 
system Sepia officinalis, a valve preventing the 
reflux of the blood towards the head. 
8 With Nautilus, this sinus is divided into four 
venae cavae (Owen, loc. cit.). 
9 The so-called Branchial hearts of the dibranch- 
iate Cephalopoda have no muscular fibres, but 
have avery glandular aspect, and are in close re- 
lation with the urinary organs; see below, § 256. 
10 Delle Chiaje, loc. cit. Tay, LXXXVII. 
LXXXIX. XCI. XOrH. (17, 27, 21, 23), has also, 
figured with many details the venous system of 
Octopus, Sepia, and Loligo. 
11It is, therefore, difficult to decide if the large 
cavities which Milne Edwards (Ann. d. Sc. Nat. 
TIL. loc. cit. Pl. XITI-X VI.) has injected, were di- 
lated veins or simple lacunae. In this last case, 
the venous system would communicate directly with 
the cavity of the body, and there are many circum- 
stances in favor of this view. It is, therefore, to be 
regretted that Milne Edwards did not, in his re- 
searches, pay more attention to the aquiferous sys- 
tem which is spread through the whole body of 
the Cephalopoda, and thus, for the present at 
least, prevent the objection, that these aqueous 
reservoirs should be confounded with the venous. 
sinuses. The lymphatic reservoirs which, according 
to Erdi (Wiegmann’s Aych. 1843, I. p. 163) sur- 
round, and can be injected by means of the arteries, 
are also. perhaps, venous sinuses. An observation 
of Owen (On the Nautilus, p. 27, Pl. VI. fig. 1, 
No. 1), or Isis, p. 24. Taf. IV. or Ann. d.Sc. Nat. p. 
121, Pl. IIL. fig. 2, No. 14), and of Valenciennes 
(loc. cit. p. 287), that the large superior vena cava 
communicates with the abdominal cavity by nu- 
merous orifices, is of much importance. For, in this 
way, this vein must be regarded as a large blood- 
reservoir, conducting, very probably, the nutritive 
fluid, after its transudation through the intestinab 
canal, into the general blood current, 
The pericardium of the Cephalopoda sustains, 
perhaps, analogous relations to the blood-system, 
for, with Nautilus, it is said to communicate with 
the abdominal cavity, and with the principal vena 
cava, with the other Cephalopoda ; see the conclud- 
ing paragraph of note 1, § 261. 
