10 Sea Lilies. 



represent the series of joints between any two nodes. A third 

 row of small plates shortly appear between, and alternating 

 with, the two first rows. These are the first radials, they are 

 hidden by the centro-dorsal plate in the mature form. At the 

 same time a month becomes evident in the centre of the upper 

 row of plates, and a circlet of delicate flexible hollow tentacles, 

 the first indication of the growing arms, fall curving over the 

 edge of the cup. Two more radial joints are next formed ; then 

 the arms bifurcate ; pinnules begin to appear, and at length 

 we have a perfect miniature Comatula, about half an inch 

 across from tip to tip of the arms, fixed to a stone or weed by 

 a jointed calcareous stem sometimes nearly an inch long. We 

 have already seen how closely Comatula resembles in structure 

 the heads of the great stalked Crinoids ; in its embryonic or 

 larval condition, fixed by a stem to the ground, the resemblance 

 is complete. The permanent ring at the top of the stem of 

 the young Comatula throws out cirrhi, and goes on growing 

 into the centro-dorsal plate, and, finally, the connection between 

 this plate and the next joint of the stem gives way, and the 

 young Comatula swims once more free. 



I have now rapidly sketched the structure of the three 

 typical representatives of the almost lost group of Crinoids 

 which are now found living — Cenocjeinus, Neockinus, and Co- 

 matula. In the first type there can be little doubt, from the 

 great strength and rigidity of the stem, and from the absence 

 of all provision for its rupture, that the animal is stalked and 

 attached for life. The arms are greatly multiplied, large and 

 strong. No syzigies, save those at the base, which can be used 

 on an emergency, tend to diminish their strength — an arrange- 

 ment essential to the full supply of food in their fixed condition. 

 The disk is uniformly defended and plated with calcareous 

 pavement, and the mouth is armed with teeth for the destruc- 

 tion of any wanderer whose fate may lead him within the ruth- 

 less circuit of the net-like arms. 



In Neoceinus there is an evident arrangement for the rup- 

 ture of the stem in the syzigie between the upper nodal joint, 

 to which the cirrhi are actually attached, and the lower joint, 

 which is grooved to suit their curve in starting from the stem. 

 This syzigie is between the nodal and the first internodal joint, 

 and therefore exactly in the position in which the same provi- 

 sion for the severance of the stem occurs in the Cenocrinoid stage 

 of Comatula. We have evidence from the existence of this 

 provision, and from observation, that at a certain period of its 

 life Neocrinus becomes free. The number of arms in this .se- 

 cond type is greatly less, and the arms are provided throughout 

 with syzigies, an arrangement apparently suitable to its greater 

 liability to trivial accidents in its free condition. The mouth is 



