170 THE ANNELIDES. $ 157. 
only in the anterior segments of the body.© With the genus Lumbricus, 
the cardiac organs consist of five to nine pairs of moniliform, transverse 
canals, situated above the stomach, and whose pulsations are very dis- 
tinct. With all the Abranchiati yet examined, the blood is red. 
With the Capitibranchiati, there are often two dorsal vessels, one imme- 
diately subcutaneous, the other lying, as usual, on the intestine.“ This 
duplicity of the dorsal vessel is observed particularly with those species 
which have a coiled intestinal canal.“ In this case, there is also a second. 
ventral vessel accompanying the coils of the intestine. All these longitudi- 
nal vessels interanastomose very frequently, and send many transverse: 
branches to the intestine and the walls of the body, where they blend with the 
capillary system. Not unfrequently, the dorso-intestinal vessel is dilated 
at its anterior extremity, above the pharynx, into a large, pulsatory, heart- 
like canal, which sometimes has two lateral arcuate, sinuses situated at the 
commencement of the intestine. The extremity of this vessel sends off, 
right and left, many branches to the branchiae, which are situated in this 
region, Leaving these organs, these vessels are distributed, some in front 
to the tentacles, and to the other organs surrounding the mouth; while 
others pass below to unite with the ventral vessel. As the blood is thrown 
from behind forwards in the dorsal vessel, and thence passes into the bran- 
chiae, this vessel may be called a dorsal vein, and its dilatation a branchial 
heart; while the ventral vessel. which receives the returning blood from the 
branchiae, would be an abdominal aorta. But there are other reasons for 
this view. The dorso-intestinal vessel, from its intimate connection with the 
liver, might well serve the function of a Vena portarum, while the close 
union of the ventral vessel to the ventral cord, is undoubtedly for the purpose 
that the latter, as a central nervous mass, may receive arterialized blood di- 
rectly from the branchiae. With these animals (the Capitibranchiati), the 
blood is red in some, and green in others.“ 
The Dorsibranchiati often have double dorsal and ventral vessels, two of 
which belong to the intestinal canal, and two to the walls of the body.“ 
With some, these longitudinal vessels are divided into two or three branch- 
es.“ The principal dorsal vessel is sometimes dilated at its anterior-ex- 
tremity, above the pharyngeal tube, into a cardiac sinus, to which, at the 
beginning of the intestine, there are added two lateral, arcuate dilatations. 
9 Enchytraeus, Chaetogaster, and Nats. The 
vascular system of Euaxes and Lumbriculus is 
very remarkable in this respect. Instead of trans- 
verse anastomoses, there are, in each segment of the 
body, two vessels which pass off from the dorsal 
trunk, and divide into many coecal branches ; see 
Treviranus, Beohacht. aus d. Zoot, loc. cit. p. 60 5 
and Grube, in Wiegmann’s Arch. 1844, I. p. 205, 
Taf. VI, fig. 1, 2, d. 
10 See Duges, loc. cit. Pl. VIII. fig. 1, and Mor- 
ren, loc. cit. p. 162, Tab. XX.-XXIIL., XXI=- 
XXIV. fig. 1. 
11 Milne Edwards has made very beautiful re- 
searches upon the vascular system of the Capiti- 
branchiati; see Ann. d. Sc. Nat. X. 1838, p. 193, 
Pi. X. XL. j 
12 Amphitrite and Siphonostomum; see Rath- 
ké. Danzig. Schrift. loc. cit. p. 76, 88, Taf. V. fig. 4,5. 
13 With Terebedia, there is a vascular heart and 
two lateral sinuses; see Milne Edwards, loc. cit. Pl. 
X. XI. fig. 1. With Siphonostomum, there is a 
similar cardiac dilatation upon the pharynx, and it 
is divided into two chambers by a well-marked 
constriction at its posterior part ; see Rathké, loc. 
cit. p. 89, Taf. VI. fig. 5, f. g. a 
14 With Terebella, Amphitrite, and Serpula, 
the blood is red ; with Siphonostomum, Chlorae= 
ma, and some species of Sabella and Serpuia, it is 
green. 
15 We are indebted to Milne Edwards for very 
detailed accounts of the vascular systsm of the Dor= 
sibranchiati ; see Ann. d. Sc. Nat. loc. cit. Pl. XI. 
XIIL.; see also, for that of Areniccla, Stannius, 
in Miiller’s Arch. 1840, p. 357. 
16 With Eunice sanguinea, there is a double 
dorso-intestinal vessel (Milne Edwards, loc. cit. 
Pl. XII. fig. 2,34); and a double ventral one 
with Nephtys Hombergi. With Arenicola, there 
are three ventral vessels accompanying the ventral 
cord (Miller, in Burdach’s Phys. loc. cit. p. 147). 
and with Amphinome, Grube has found three 
dongs ones beside, all widely separated from each 
other. 
W7 Eunice ; see Milne Edwards, loc. cit. Pl. 
XII. fig. 2. The vascular system here resembles 
that of T'erebella. 
