Haddon and Shackleton — Actinue : I. Zoanthece. 679 



Dimensions. — Height 7-12 mm. ; diameter of disc, 6 mm. 



Locality. — Fringing Reef, Mer (Murray Islands), Jan. 29, 1889. Numerous 

 specimens. 



We associate this species with the name of the late Prof. Beete Jukes, at one 

 time Professor of Geology in the Eoyal College of Science, Dublin, who was also the 

 author of the interesting Voyage of the " Fly."* To this day the name of this 

 genial naturalist is still remembered in the Murray Islands and in Erub. 



Body-ivall (PI. lxii., fig. 2). — A cuticle and peripheral mesogloea are present 

 as in Z. cofpingeri. The cells of the ectoderm are not distinct but appear to have 

 become fused, as in the specimen of Z. sociatus, described by M^Murrich (1889a, 

 p. 63). For the most part they appear to form a quite continuous and narrow 

 layer, but in some parts the contents of the cells, adhering closely to the mesogloea 

 on either side, leave an empty space, across Avliich, irregularly placed and 

 exceedingly delicate strands of mesogloea are seen to pass. Anastomosing canals, 

 connected with the ectoderm, are present, though not at all so numerous as in 

 Z. copping eri. Lacunse, clearly of similar origin, but completely surrounded by 

 the mesogloea, are more frequently to be met with. The canals and lacunae are 

 most abundant in the lower part of the column, and here their connexion with the 

 basal canals of the mesenteries can be demonstrated (PI. lxii., fig. 2). The 

 mesogloea is of the usual character. Zooxanthellse also abound in the endoderm of 

 this species. There is a diffuse endodermal muscular layer, supported by acute 

 mesogleal prominences. 



Capitulum. — The ectoderm of the capitulum is thrown into folds, as in Z. cop- 

 pingeri, and rather opaque oval cells, with a clear outline (probably nematocysts, 

 are here very numerous, being generally embedded singly in in the mesogloea. 



Sphincter muscle. — The sphincter muscle is not so strongly developed as in 

 Z. coppingeri. Of the two parts of the muscle the upper one is in this case the 

 longer. The muscle cavities are larger and less filled up with cells, the plaitings of 

 the mesogloea being simpler than in Z. coppingeri. 



Disc and tentacles. — The ectoderm of the disc and tentacles closely resembles 

 that described for Z. coppingeri. The endoderm is crowded with zooxanthellse, 

 but contains no nematocysts. 



The ectoderm of the oesophagus is thrown into slight folds. The groove is 

 well marked (PI. lxii:., fig. 1). 



Mesenteries {V\. LXiii., fig. 1). — The arrangement of the mesenteries is of the 

 usual brachycnemic type. The reflected ectoderm of the oesophagus forms a smaller 



♦ Narrative of tte Surveying Voyage of H. M. S. " Fly," commanded by Captain F. P. Blackwood, E.JS". 

 (dui-ing the years 1842-1846). 1847. By J. Beete Jukes. 



