Explanation of Plate III. 



Fig. i. Transverse section through the sphincter muscle of Zoautkus 

 sociatus. 



Fig. 2. Epizoant hns hians on worm tube. About natural size. 



Fig. 3 Longitudinal section through the upper part of the column of Epi- 

 zoanthns hians. st = stomatodaeum ; sp = sphincter; t = tentacle. 



Fig. 4. Transverse section through the sphincter muscle of Epizoanlhiis 

 hians. 



Fig. 5. Transverse section through a portion of the column wall and mes- 

 enteries of Epizoanthns hians, below the level of the stomatodreum. 

 I=inclusions in mesoglcea; l=lacun;u. 



Fig. 6. Transverse section through part of the column wall of Palythoa 

 nigricans. I =rinclusions in mesoglcea; 1 = lacuna;. 



Fig. 7. Longitudinal section through the upper part of the column wall 

 of Palythoa nigricans, sp = sphincter muscle; I = inclusions in 

 mesoglcea; 1 = lacuna;. 



