Knob, not in the center of the abors.1 disk it is 

 true, but on its edge. In the star.-fishes it may bo 

 recalled that the preoral lobe disapp;-ar:; on the 

 oral surface of the metamorphosing star. 



To the above larval characteristics may be 

 similaritiy which exists in the iicpccition of 

 fcfie alimentary and coelomic systems in the adult 

 form. 



In both Crinoids and Ophiurids the digestive 

 apparatus is confined to th^ disk. 



The body cavity is continued into and to the 

 ends of the arms. When a transverse section of a 

 pinule of Antedon is compared with b transverse 

 section of an ophiurid ar&, the following strifc 

 correspondence is found in the parts. Aborally, seg- 

 mentally arranged calcarious ossicles and muscles 

 are present. A continuation of the body coelom runs 

 between and oral to the muscles. Connected with 

 on each side of this central brachial body cavity 

 are two other cavities, the subtentacular canals, 

 These latter , in Ophiura, are connected with the 

 perihaemal space in each vertebral segment. 



The radial water tube lies between the subt.n- 



