MINUTE ANATOMY OF THE BRACHIATE ECHINODERMS. 185 
or eastern angle of the mouth,' where it gives off a large 
bundle of vessels. These pass downwards and backwards, 
slightly above the gullet (figs. 14, 15, ae. 6.), to near the 
centre of the visceral mass, where they communicate with 
the lower portion of the intervisceral network of vessels that 
is spread out, as in Antedon (19), over the coils of the intes- 
tine. This cesophageal bundle is seen in longitudinal sec- 
tion in fig. 14 (ae. 6.), and cut transversely in fig. 15, which 
represents a cross-section through the disc of Actinometra 
polymorpha, seen from its anterior face, so that the struc- 
tures which are (w) in the figure are (£) in the disc, and vice 
versa. 
The labial plexus also gives origin to the genital vessels 
which extend outwards beneath the ambulacra of the disc 
(figs. 14, 15, g.v.); and from the smaller portion of it that 
lies in front of and below the mouth there passes backwards, 
slightly below and on the right (w) of the gullet, a more 
compact bundle of vessels, which enlarges slightly beneath 
the centre of the visceral mass, bends directly downwards, 
and enters the calyx (figs. 14, 15, c.p.). This corresponds 
to the central plexus of Antedon, and, like it (19), is con- 
nected laterally with a close network of intervisceral blood- 
vessels at the lower part of the visceral mass, that also 
receives the vessels of the cesophageal bundle, as shown in 
fig. 14. Vessels extend backwards from this network, and 
also to the right and left, so as to completely surround the 
complicated windings of the alimentary canal. Some of them 
are quite large, and frequently contain coagulum. They 
interpenetrate the rather close network of connective tissue 
that fills up all the unoccupied portions of the body-cavity 
(figs. 14, 15, ¢.). 
Up to this point we have found the Crinoids to conform, 
on the whole, to the type of the Starfishes and Ophiurids. 
There is, it is true, no real aboral ring, unless the labial 
plexus with which the genital vessels are connected may 
be considered as generally homologous with the aboral ring 
that connects the genital vessels of Starfishes and Ophiu- 
rids ; but no detailed comparison of the two is at all possible. 
The Crinoids are also unprovided with any definite peri- 
hemal system. For even supposing that Ludwig is cor- 
rect in regarding the genital canal as the perihemal canal 
of the genital vessels (27), there is absolutely no trace of any 
perihemal canal around the radial blood-vessel. Neither is 
it easy to define any special portions of the body-cavity as 
1 The mouth is supposed to be N, or pointing forwards away from the 
observer. : 
VOL, XXI.—NEW SER, N 
