EOSACEUS, LINCK (COMATULA EOSACEA OE LAMAECK). 
529 
with the leaf, and along with it communicating with the vessel. One of these tentacles 
(the distal one) is somewhat larger than the proximal; they are both slightly club- 
shaped, the club-shaped extremity fringed on either side with conical papillae. They 
are non-extensile, and resemble in every particular the ten non-extensile tentacles early 
developed from the oral ring. A group consisting of a crescentic leaf and two non- 
extensile tentacles lies immediately at the base of each extensile tentacle, and a little 
lower down the arm (Plate XX,VII. fig. 3 d). Minute spicules, some of them simple or 
key-shaped, and others expanding into a cribriform film, appear in the superficial sar- 
code-layer along the back or edges of the arms ; and, usually at the base of each of the 
tentacles, irregularly imbedded in the sarcode-substance, there is one of the calcareous 
glands. 
Immediately on the expansion of the equatorial portion of the cup, the wall of the 
stomach becomes separated by a distinct body-cavity filled with fluid, from the body- 
wall. The stomach seems to hang in this cavity as a separate sac, attached to the body- 
wall here and there by sarcodic bands and threads. As the disk expands, the radial 
canal may be distinctly seen rising from the oral ring, crossing the narrow disk and run- 
ning along the upper surface of the arm, communicating on either side with the various 
tentacles and respiratory leaves, and ending at the extremity of the arm in the azygous 
tentacle. Beneath the radial canal a tubular extension of the perivisceral space passes 
along the radial grooves. This series of vessels, for which Dr. Carpenter proposes the 
term “ cceliac canals,” afterwards extends throughout the whole length of the arms. In 
the mature Antedon Dr. Carpenter has observed a third vessel intermediate between 
the coeliac and tentacular canals; but no trace of this vessel can be detected in the 
earlier stages in the development of the pentacrinoid. 
A little later, the end of the arm shows a tendency to bifurcate, and two half rings, 
with their enclosed sheaves of calcified tissue, give the first indication of the first two 
brachials. At the stage which I have described the arm is free, from the base of the 
second radial ; at a later stage the visceral sac extends to the bifurcation, and the whole 
of the radial portion of the arm becomes included in the cup and disk. The azygous 
tentacles go no further than the bifurcation. They remain for some time in the centre, 
between the two divisions of the arm, while secondary branches from the radial canal 
run on in the brachial grooves. About the period of the development of the second 
radials, a forked spicule makes its appearance in one of the interradial spaces between 
the upper portions of two of the first radial plates. This gradually extends in the usual 
way till it becomes developed into a round cribriform superficial plate. 
Simultaneously with the appearance of this “ anal ” plate, a ceecal process like the 
finger of a glove rises from one side of the stomach and curves towards the plate. The 
plate increases in size, becomes enclosed in a little flattened tubercle of sarcode, and 
maintaining its upright position it passes slightly outwards, leaving a space on the edge 
of the disk between itself and the base of the oral plate immediately within it. 
Towards this space the csecal intestinal process directs itself. It rises up through it 
mdccclxv. 4 c 
