650 Haddon and Shackleton — A Revision of the British Actinice. 



Body-wall (PI. lix., fig. 1). — The ectoderm is much broken, owing to the 

 incrustations. Where present it is continuous, and is covered by a thin cuticle. 

 Thread cells, containing a few, almost black, pigment-granules, are occasionally to 

 be met with amongst the columnar cells of the ectoderm. The mesogloea is 

 thinner relatively to the diameter of the column than in most species of Zoanthese. 

 The incrustations consist almost exclusively of foraminifera, which are fi-equently 

 so large that a single specimen extends right across the body-wall, and is partly 

 embedded in the ectoderm and partly in the endoderm, as well as in the mesogloea. 

 There are hardly any cell-enclosures in the mesogloea. Single cells only are 

 occasionally to be seen enclosed. The endodermal muscular layer appears to be 

 fairly well developed. The endoderm is formed by a thin layer of columnar cells 

 of uniform height. 



Sphincter muscle. — The single mesogloeal sphincter is thick, extending right 

 across the wall of the capitulum. The cavities in the mesogloea are large. 



Disc and Tentacles. — The nuclei of the ectoderm are diffused, and do not form a 

 central band. The muscular layers are well developed. 



CEsojjhagus. — The ectoderm of the oesophagus appears to be quite smooth, not 

 being thrown into folds. Tlie groove is well marked, and there is a slight thicken- 

 ing of the mesogloea in this region. 



Mesenteries. — The arrangement of the mesenteries is macrocnemic. Owing to 

 the presence of a parasitic crustacean in the single specimen we have cut it is 

 difficult to determine the details regarding the mesenteries. The imperfect 

 mesenteries extend but a short way into the body-cavity. The mesogloea is 

 well develo^ied, and is thrown on one side of each mesentery into distinct plaitings, 

 which support the longitudinal muscle-fibres. The parieto-basal muscles are less 

 well developed, and appear to extend but a short way from the body-wall. 



Gonads. — We found no gonads. 



Parasitic Crustacean. — It is impossible to determine the nature of the crustacean 

 infesting our specimen, or to say whether it is a fully developed or a larval 

 form. 



[Epizoanthus norvegicus (Kor. & Dan.). (Not British, Norway.) 



(PI. LIX., fig. 5.) 



Form. — Ratlier more clavate than E. macintoshi ; coenenchyme forming expan- 

 sions, in which the polyps, in the specimens we have examined, appear to have 

 a tendency to form linear series. 



Colour. — Sandy brown (in spirit). 



Dimensions. — Height, 6-12 mm.; diam., about 6 mm. 



