10 Ech. 
ECHINODERMATA, 
is likewise a prolongation of the inter- visceral body-cavity ; it contains 
suspended the genital vessel, enclosing the true genital tube, whose 
internal investing cells give origin to the ova or sperm-cells in the inferior 
(proximal) piunula), while it commonly remains sterile in the arms them- 
selves and in the oral pinuulm. Special apertures are formed for the 
exit of the sperma, probably also for that of the ova. The coloured 
globular corpuscles accompanying the tentacles (falsely interpreted as 
“ calcareous glands,” or as sense-organs) are also found in the body- 
cavity along the intestinal tube ; they are not wanting, though colour- 
less, on the ambulacra of Ehizocrinus. The enigmatical five-chambered 
organ, situated in Antedoriy etc., in the centro-dorsal knob, below the 
transformed basalia [on its somewhat different placement in other 
recent and fossil genera, compare especially Carpenter (2)] turns out 
to be only the dilated inferior portions of five vertical vessels, the outer- 
most of an axial bundle, prolonged from the stem through the funnel in 
the centre of the first radials, and continued into the “ dorsal organ,” 
which is a vascular plexus, corresponding with the “ heart ” of starfishes, 
and communif-ating distally with the oesophageal and visceral vascular 
plexus. (In Ehizocrinus, the axial vessel appears to be single, not a 
plexus.) The cirral vessels spring from the inferior end of these axial 
vessels, or (the five uppermost) from the five chambers themselves ; they 
arc enclosed in fibrillar sheaths, prolongations from the fibrillaied sub- 
stance surrounding the five-chambered organ and its dependencies. The 
“ostia dorsalia ” of this organ are (Carpenter) the remnants of the pro- 
longation into the stem of the five peripheral vessels encircling the axial 
vessel in stalked Crinoids or crinoidal larvae. In Fentacrinus, the cirral 
vessels spring from similar heart-like dilatations of the five peripheral 
vessels of the stem, exactly the counterparts of the single one remaining 
in the calyx of free Crinoids (Carpenter, 2). [Compare also this author 
concerning the somewhat different placement of this organ in Ehizo- 
crinus, and in other recent or fossil genera.] The axial cords of the arms 
and radii also originate from the fibrillated mass surrounding the 
“chambered organ,” but contain no vessels, nor can they, according to 
Ludwig, be regarded as an anti-ambulacral nervous system, as indicated 
by the suggestive experiments of W. Carpenter; they are, in Ludwig’s 
opinion, essentially the uncalcified remnants of the connective tissue of 
the rays, though they may have, physiologically, other nutritive func- 
tions to perform. The structure of Ehizocrinus, as far as the soft parts 
are concerned, is in all important points analogous to that of Antedon, 
etc., but somewhat more simple. As to the interpretation of the parts 
regarded as “ basalia ’* and “ uppermost stem-segment ” in Ehizocrinus, 
by Sars, Pourtal^s, Ludwig, and Carpenter respectively, there is still a 
difference of opinion. 
P. Carpenter’s second (preliminary) paper (3) discusses the relations 
of Antedon and Actinomeira, which latter genus is redefined (in accord- 
ance chiefly with the observations of the Ilecordcr), and limited to the 
species with excentric mouth and (commonly) flagelliform and pectinated 
oral pinnulae. It is further shown that in some Actinometroi the mouth is 
placed radially, in others iuter-radially, and that in several species there is 
