■ Haddon and Shackleton — Actinice : I. Zoanthece. 699 



the surface of our specimens. Where present the ectoderm appears to be con- 

 tinuous. It is not penetrated by strands of mesogloea, nor is there a peripheral 

 layer of mesogloea. The cuticle is very delicate, and difficult to discern. Beneath 

 the incrustations, and separated from the endoderm by a narrow band of mesogloea, 

 is an encircling sinus filled with dark brown granular pigment. It is crossed at 

 intervals by strands of mesogloea. A few branching canals connected with the sinus 

 run outwards through the mesogloea among the incrustations. Small, round or 

 oval groups of cells, the cell-islets of Erdmann, are scattered throughout the 

 mesogloea; a very few pigment granules can be seen in some of them. We have 

 not observed any connexion between the sinus or the canals connected with 

 it and these islets. The endoderm is richly pigmented. We have seen no 

 zooxanthellse. 



The capitulum, which in contracted sj)ecimens is thrown into deep folds, is 

 also incrusted ; but there is a much larger prop)ortion of spicules and relatively 

 fewer sand particles than in the column. The encircling sinus is not continued 

 into the capitulum. 



Sphincter muscle. — The endodermal sphincter is supported on slightly branched 

 plaitings of mesogloea. Near the upper extremity (in contracted specimens) it 

 appears to become embedded in the mesogloea, a few simple cavities being visible 

 in our sections. 



Tentacles. — The ectoderm of the tentacles is thick. The nuclei are scattered 

 diffusely through the outer part, leaving a clear band next the muscular layer. 

 Small nematocysts of the usual description are present. The mesogloea is thin and 

 almost homogeneous, a very few cell-islets being present. The endoderm contains 

 a few zooxanthellse, and occasional pigment granules. 



Disc. — The ectoderm of the disc is very similar to that of the tentacles, but it 

 contains some pigment. Numerous cell-islets occur in the mesogloea. 



(Esophagus. — The ectoderm of the oesophagus stains more deeply than that of 

 the disc or tentacles. It forms a simple layer, not being thrown into folds. The 

 mesogloea is fairly thick, especially in the region of the groove, which is well 

 marked. 



3fesenteries. — The mesenteries are arranged as in other Macrocneminse. The 

 imperfect mesenteries are very slightly developed, projecting but little beyond the 

 endoderm. The mesogloea of the mesenteries is thick, and contains cell-islets, but 

 no canals or sinuses. The longitudinal muscles are well developed and supported 

 on mesogloeal folds. The endoderm resembles that which lines the body- wall. 



Gonads. — In one of the specimens cut by us male gonads were found. 



Parasites. — Small, oval, deeply pigmented bodies occur in many parts of the 

 body in this species. They are evidently parasites, but we are unable to say 

 anything further about them. 



