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



Wright, who is so well-known as a student of the Actinozoa, and who is always 

 so ready to help his scientific colleagues. 



Body-ivall (PI. lix., fig. 3). — The ectoderm, where present, is continuous. 

 It consists of numerous granular and deeply staining columnar cells, with 

 occasional nematocysts scattered amongst them. It is protected by a thick 

 cuticle, which does not stain but is of a dark brown colour owing to the presence 

 of dark brown granules and of various foreign bodies. Incrustations chiefly 

 consisting of coarse grains of sand, with a few foraminifera, are embedded in 

 the mesogloea, which contains very few cell-islets or other enclosures. The endo- 

 derm is formed by a rather thin layel' of ordinary columnar cells. The endoder- 

 mal muscular layer appears to be but slightly developed. 



Sphincter muscle. — The single mesogloeal sphincter consists of several rows of 

 simple cavities at the distal end. Proximally it is reduced to a single row of 

 very small cavities (PI. lx., fig. 2). 



Disc and Tentacles. — There is little worthy of note in the structure of the disc or 

 tentacles. Both ectodermal and endodermal muscular layers are well developed. 



CEsophagus. — The ectoderm of the oesophagus is thrown into well-marked folds ; 

 there is a distinct groove, but little if any thickening of the mesogloea in this 

 region. 



Mesenteries. — The mesenteries have the usual macrocnemic arrangement. The 

 imperfect mesenteries are distinct, although they extend but a short way into the 

 body-cavity. The reflected ectoderm forms the mesenterial filaments in the usual 

 way. The mesogloea is not very well developed ; both parieto-basilar and 

 longitudinal muscles form almost simple layers. The endoderm is thinner than 

 that of the body-wall, and contains in addition to the ordinary columnar cells, 

 small oval cells which stain a very deep carmine. 



Gonads. — No gonads were present in the specimens examined by us. 



PROBABLY BELONGING TO THIS GENUS. 



Zoanthus rubricornis, Holdsworth. 



Zoanthus rubricornis : 



Holdsworth, 1861, Proc. Zool. Soc. : and Ann. Mag. Nat. Hist. (3), yii., p. 484, woodcut. 

 Hincks, 1861, loc. cit. (3), viii., p. 364. 

 Polythoa [Endeithoaj rubricornis : 



Andres, 1884, Le Attinie, p. 316. 



Form. — An unattached group of ten polyps, each gradually tapering from 

 above downward, incrusted with sand ; marginal serrations not nearly so 

 conspicuous as in B. couchii. 



