§ 87, 88. 
THE ECHINODERMATA. 
89 
CHAPTER VI. 
CIRCULATORY SYSTEM, 
§ 87. 
The vasoular, sanguineous system of these animals is yet mperfectly 
known. 
The constant confusion and imperfection of its descriptions are 
probably due to the fact that it has not been carefully distinguished from 
the respiratory system ; and also, as was true of the Acalephae, because it 
has been confounded with the aquiferous system, which is usually pres- 
ent, 
From all the old and new researches upon this subject, it is evident that 
all the Echinoderms have an isolated system of this kind, composed usually 
of both an arterial and venous trunk, between which there is, in some spe- 
cies, an organ like a heart. 
§ 88. 
In the Crinoidea, there is, at the base of the calyx, a heart-like saccu- 
lus, from which pass off vessels into the central cavity of the arms, the 
cirri, and the pedicle when it is present. From its centre, another vessel 
is given off for the spongy axis of the cavity of the body.” 
The Asteroidae have three vascular rings, one of which is under the 
skin of the back, while the other two are beneath, around the mouth. 
Between these vascular rings there is a long muscular heart, which, united 
to the calcareous pouch or cord, extends from the madreporal plate to the 
mouth, ~ 
It is probable that the Asteroidae, which have many of these plates, 
have also many calcareous cords and hearts.” I'rom these vascular rings 
numerous other vessels are sent off, some to the stomach and its appen- 
dages, and the genital organs, and othersto the ambulacra and their vesi- 
cles, ® 
1 The extended, and in some respects contradict- 
ory works of Tiedemann and Delle Chiaje (loc. 
cit. ; see, also, Meckel, Syst. d. vergleich. Anat. 
V. p. 25; and Sharpey Cycloped. &c. II. p. 41) 
have not, for reasons which may be stated, cleared 
up this point. The same may be said of what 
relates to the blood of these animals, for it has 
-been confounded in part with the ambulacral liquid - 
belonging to theaquiferous system. See Wagner, 
Zur vergleich Physiol. dei Blutes, 1833, p. 28. 
The observations of Delle Chiaje (Memor. &c. 
Ti. p. 345) and of Carus (Analekt zur Natur. :u. 
Heilkunde, 1829, p. 132, and Lehrb. d. vergleich. 
zoot. 1834, p. 673) do not give correct ideas upon 
the mode and direction of the circulation of these 
animals ; for it is evident that they did not see it, 
but only the vibratile phenomena of the aquiferous 
system. 
1 The vascular system of Comatula and Pen- 
facrinus has become known through Heusinger 
Zeitsch. f. organisch. Physik. III. 1828, p. 373, 
‘af. X. XI.) and Mudler (Abhandl. d. Berl. Akad. 
1841, p. 198, 236, Taf. V.). The membranous canal, 
Q% 
situated beneath the nervous branches of the arm, 
and directly above the calcareous articulations, and 
the passage of which through the arm into the 
calyx Miller (loc. cit. p. 233) has not beem able 
to clearly make out, is probably a blood-vessel. It 
is yet unknown how the blood of these vessels is 
distributed to the organs. 
2 As in Echinaster solaris, and Ophidiaster 
i ala see Muller and Troschel, loc. cit. 
8 According to Tiedemann (loc. cit. p. 49, Taf. 
VIII.), the lower extremity of the heart of Astro- 
pecten aurantiacus opens into the vascular ring 
which surrounds the mouth. This last sends arte- 
rial’ branches to the stomach, the coeca, and the 
genital organs; the superior extremity of the 
heart icates in like with another 
vascular ring upon the back, and which receives the 
veins of the organs just mentioned. From a third 
and reddish vascular ring, situated directly under 
the skin of the mouth, Tiedemann has seen pass 
into each ray a vessel placed superficially in the 
furrow of the ambulacra, but he did not ascertain 
