316 MRS. L. J. WILSMORE ON ZOANTHE^ FROM 



.Dimensions. — Height 3-12 mm. ; average height 6 mm. ; diameter 

 3-5 mm. 



Locality. — Collected in Erikor Lagoon, Sandwich Island, New Hebrides, 

 by Mr. W. T. Quaife, in April 1903. 24 specimens. 



The specific name sandvicensis refers to the island in the New Hebrides in 

 whose waters they were collected. 



Column-wall (PL 44. fig. 2). — A cuticle and subcuticle are present. 

 Numerous foreign bodies, mainly diatoms, adhere to the cuticle. The 

 ectoderm is discontinuous, and the connecting strands of mesogloea pass 

 at frequent and regular intervals from the mesogloea to the subcuticle. 

 Nucleated ectodermal cells are present more or less abundantly in some of 

 the cavities thus formed ; in others they are not to be distinguished. It is 

 probable that shrinkage has taken place as large vacuoles are of frequent 

 occurrence. Large oval nematocysts are present. The mesoglnea is thick, 

 averaging 0*29 mm. The numerous canals and small sinuses present are not 

 definitely enough arranged to give the appearance of a broken encircling 

 canal. The lacunse contain nucleated cells and nematocysts. Enclosed cells, 

 both with and without fibrillate terminations, are very numerous, especially 

 towards the base of the polyp. The endoderm, which is thick, contains 

 occasional nematocysts and is crowded with zooxanthelljB in the region of 

 the capitulum, though elsewhere they are rare. Comparativel}; few fibres 

 run from the endoderm into the mesogloea. A distinct ondodermal muscle is 

 to be seen in longitudinal sections. 



Capitulum. — The capitulum is thrown into some 20-24 ridges. Its 

 ectoderm is crowded with nematocysts, and its endoderm with zooxanthellse. 



SpMncter muscle (PI. 44. fig. 3). — The sphincter muscle is double and 

 embedded in the mesogloea. In contraction, the line of demarcation between 

 the two halves is very deep. The distal muscle is short but well developed. 

 Its cavities are two rows deep distally, and the muscle ends abruptly at this 

 point. The proximal muscle is very strong. At its widest part it occupies 

 almost the whole of the mesogloea, but lies throughout its course nearer the 

 ectoderm than the endoderm. In parts indeed it is only separated from the 

 ectoderm by the thinnest strands of mesogloea. The cavities are very long at 

 its widest point, and so closely packed together that the mesogloea between 

 them amounts merely to separating walls (PL 44. fig. 3). The cavities are 

 lined with muscle-cells, and the smaller cavities have in addition a few free 

 cells enclosed. The ectoderm in this region is crowded with nematocysts. 



Tentacles (PL 44. fig. 4). — In three specimens cut transversely the tentacles 

 number respectively 36, 39, and 40. The ectoderm is thick and contains two 

 varieties of nematocysts : (a) Large oval, deeply staining nematocysts with 

 distinct threads are crowded together in patches on the outer side of the 

 tentacles (PL 44. fig. 4, nem. a) ; (h) Smaller narrow, unstained nematocysts, 

 often slightly curved, are numerous in the apical region of the tentacles, 



