276 
THE OCEAN WORLD. 
cylindrical, and present a series of rays striated upon their articulated 
faces. In Pentacrinus they are prismatic and pentagonal ; that is, they 
present five projecting angles, and on their articulated face a star with 
five branches, or, better still, a rose with five petals. At the base of 
the stem of this animal-plant, in many of the Crino'idae we find a sort 
of spreading root, which is implanted in the rocks, and is capable of 
growing by itself" of nourishing the stem, and of producing new ones. 
The root and stem of the fixed encrinites seem to indicate that the 
animal can only five with the head erect. Their normal condition is 
thus quite different from that of any other of the Echinoderms, 
almost all of which keep their mouths invariably directed downwards- 
The Medusa.; heads are chiefly found on rocky beds, or in the midst 
of banks of corals, at great depths. There, firmly fixed by their 
roots, their long stems raise themselves vertically ; then, with expanded 
calyx and long-spreading arms, they wait for the prey which passes 
within their reach in order to seize it. 
Tho Pentacrinus caput Medusa; have, as we have said, been fished 
up from great depths in the Antilles. Its very small calyx is borne 
upon a stem of from eighteen to twenty inches in height, terminating 
in long movable aims, the internal surface of which bear its tentacle^ 
in a groove. In the middle of the arms is a mouth, and at the side 
the orifice for the expulsion of the digested residuum. 
In the Medusae head and European Pentacrine (P. Europ% llS > 
Fig. 108), the presence of a digestive apparatus has been distinctly 
traced. It is a sort of irregular sac, with a central mouth on the 
upper surface, and another orifice situated at a little distance from th 0 
mouth, and evidently intended as an outlet for the products of dig 0S " 
tion. The arms of these creatures, which are spreading or folded 11 P 
according to their wants, are provided with fleshy tentacula, which; 
serving at once as organs of absorption and as vibratile cils, are at the 
same time organs of respiration. Such are these curious beings : they 
occupy a sort of middle or transition state between animals permanently 
fixed to some spot and those capable of motion, representing in 0111 
own times the last remains of extinct generations. Every type of th 0 
Ormokbe furnished with arms present incontestable examples in their 
mode of reproduction or redintegration — that is, of the power of i e 
storing those parts of the body broken or destroyed by accident ; bn 
as we have already drawn the attention of the reader to this strang 
