644 H ADDON AND Shackleton — A Revision of the British Actiniae. 



developed ; the fibres are supported on slight, rounded plaitings of mesogloea. 

 The endoderm consists of a single layer of columnar cells, the peripheral portion 

 of the cells being of a deep brown colour owing to the presence of pigment- 

 granules. 



Sphincter muscle. — The single mesogloeal sphincter is not a very powerful 

 one. No cavities are visible, the fibres being completely embedded in the 

 substance of the mesogloea. 



Tentacles. — The ectoderm of the tentacles is thrown into transverse folds. 

 Numerous pigment-granules are to be found amongst the usual small nematocysts, 

 and the nuclei in the peripheral portion. The muscular layer is not well 

 developed. The mesogloea forms an extremely thin layer. The endoderm is also 

 pigmented. 



Disc. — The disc is very similar in structure to the tentacles. 



CEsojyhagiis. — The ectoderm of the oesophagus is thrown into numerous folds. 

 There is a well-marked groove. The mesogloea forms a thin layer, except in the 

 region of the groove where it is somewhat thicker. It contains a few cell-islets. 



3fesenteries. — The mesenteries have the usual macrocnemic arrangement. 

 The reflected ectoderm of the oesojohagus is attached to them in the lower part 

 of the oesophageal region and lower down forms the filaments as in other 

 Zoanthese. The mesogloea is well developed in the oesophageal region, and here, 

 on one side of each mesentery, plaitings which support the longitudinal fibres can 

 be distinctly seen. Plaitings on both sides of the mesentery nearer to the body- 

 wall which support the parieto-basilar fibres are exceedingly slight. The mesogloea 

 is much thinner in the lower part of the body. The endoderm is very similar to 

 that which lines the body -wall. 



Gonads. — The sexes are distinct. Male gonads are present in our sections ; 

 they are very numerous, and closely packed together, almost entirely filling up the 

 body-cavity below the oesophagus (PI. lx., fig. 5). 



Epizoanthus couchii (Johnston). 

 (PI. Lviii., figs. 26-28 ; PI. lix., fig. 4 ; PI. lx., fig. 3.) 



Zoanthus couchii : 



Johnston, 1838, in Couch, Cornish Fauna, in., p. 73, pi. sv., fig. 3 (not of Thompson, 1843, 

 Br. Assoc. Kep., p. 284 ; nor of Thompson, 1844, Ann. Mag. Nat. Hist., xm., p. 440; nor of 

 Landsborough, 1845, ibid., xv., p. 327; all of •which are Sarcodictyon catena, cf. Johnston, 1847, 

 I.e., p. 180). Forbes, 1844, Ann. Mag. Nat. Hist., xiv., p. 415. Johnston, 1847, Brit. Zooph., 

 ed. 2, p. 202, pi. xxv., fig. 9. Landsborough, 1852 (in part), Brit. Zooph., p. 225. Thompson, 

 1856, Nat. Hist. Ireland, iv., p. 462; Holdsworth, 1858 (in part), Proc. Zool. Soc, p. 557, 

 pi. X., figs. 4-7. Wright and Greene, 1858, Brit. Assoc. Eep., p. 180. Gosse, 1860, var. linearis, 

 Brit. Sea Anem., p. 297, pi. x., fig. 5. Hincks, 1861, Ann. Mag. Nat. Hist. (3), rm., p. 363. 



