244 M. M I YA JIM A : 



a part of the disc. Just above the flattened base the tentacle 

 assumes the form of a tube, 4 mm. in diameter, and tapers 

 gradually towards its free end. 



The hydranth (Woodcut 1, I. II.) contains a wide cavity 

 which is separated by a thin membrane (???) into two parts, an 

 upper (H) and a lower (H'). The superior prolongation of the 

 upper cavity is that of the hypostome, which does not show 

 any indication of the septal partition. The lower cavity is more 

 spacious than the upper, and not only occupies the whole lower 

 part of the hydranth but extends also through the entire length 

 of the hydrocaulus. 



The membrane {m) separating the hydranth-cavity arises 

 diaphragm-like just below the upper wall of the disc. In about 

 the center of this diaphragm, directly below the mouth, is an 

 ovoid orifice (Woodcut 1, II, C) which puts the upper and lower 

 cavities in communication with each other. The orifice is 

 11 mm. and 15 mm. respectively in its transverse and sagittal 

 axes. 



That part of this diaphragm which corresponds to the part 

 of the upper surface of the disc marked B in Woodcut 2, i.e. to 

 the basal part of the hypostome, projects into the cavity of 

 the hydranth like a shelf, with the aforesaid opening near its 

 middle and with no attachment either above or below. Outside 

 this portion, however, the diaphragm forms the floor of the 

 radial canals mentioned above, so that it is suspended, so to sjDeak, 

 by the numerous intercalated cords {vide supra) to the upper 

 surface of the disc. At the margin the diaphragm is united to 

 the outer wall of the hydranth (Woodcut 1). 



To show the somewhat complicated relations existing between 

 the marginal tentacles, radial canals, intercalated cords, etc., a 



