Cyathocrmus. Here 1 belie^æ, lioweAær, the resemblance
betAA'een Hyoarimis and tlie early fossil forms
ends. The outer part of the disc is pa^æd Avith plates
irreg'ular in form and closely set. E.ound the mouth
there are ÛA'e A'ery strong and definitely sliaped valves,
slightly cupped ahove, and marked beneath Avith
impressions for the insertion of muscles. The anal
opening is on a short plated interradial tube. The
F ig. 26.—Disc of Hyocrinus hetkellianus. Eight time.s the n atural size.
mouth opens into a short slightly constricted oeso-
phagns, AAdiich is succeeded by a dilatation surrounded
hy hroAvn glandular ridges; the intestine is very
short, and contracts rapidly to a small diameter,
lloand the oesophagus a someAvliat ill-defined vascular
ring, Avhich may possibly he continuous Avith the
hody cavity, glA'es off opposite each of the oral plates
a group of four tubular tentacles. The ovaries are
very long, extending nearly the Avhole length of the
first tAVO or three pairs of pinnules on each arm.
The assemblage of characters connected with the disc
and soft parts shows a considerable resemblance
between Ilyociùnus and Rhizocrinus. My strong
impression is that the mode of nutrition of the
Cyathocrinidæ, and consequently the structure and
arrangement of their disc, was essentially different
from that of all the yet known living forms ; and I
think it is probable that when we have an opportunitv
tine ; g. loose areolated connective tissue. Eight times tlie n a tu ra l size. ’ ' ’
of Studying the structure of Ilyocrimis minutely
Ave shall find that its very striking resemblance to
Rlatycrinus is to a great degree superficial.
There seems to be little doubt that RUzocrimis
finds its nearest known ally in the chalk Bourcjiiet-
ticHims, and that it must be referred to tbe Apio-
ciinidaA; Avere it not that there is an evident relation
TT 2