678 Reports on the Zoological Collections made in Torres Straits, 1888-1889. 



Disc. — The structure of the disc is very similar to that of the tentacles, but we 

 have not found nematocysts in the endoderm of this region. 



(Esophagus. — The ectoderm of the oesophagus forms a simple layer. The 

 groove is visible, although not very well marked. The mesogloea is extremely 

 thin, and of uniform thickness. 



Mesenteries. — The arrangement of the mesenteries is brachycneinic. They 

 are coiled and folded, almost entirely filling up the body-cavity. The ectoderm 

 of the oesophagus is reflected upwards and continued downwards into the 

 mesenterial filaments, forming numerous folds along each mesentery (PI. lxiv., 

 fig. 4), in a manner which will be more fully described in our account of 

 Z. macgillivrayi. The mesoglcea is extremely thin in the upper part of the 

 mesentery, although thicker in the immediate neighbourhood of the wall, where 

 it usually contains a "basal" canal. Lower down the mesogloea is thicker 

 throughout, and here the canal expands to form the large sinus, which, as we 

 have previously mentioned, is connected with the ectodermal canal system of the 

 body -wall (PI. LXii., fig. 1). The endoderm of the mesenteries forms a deeper 

 layer than that of the body-wall, and zooxanthellse, though present, are not 

 nearly so numerous. The nuclei of the columnar cells form a peripheral band, 

 leaving a clear space next to the mesogloea. Nematocysts are also to be found 

 in the endoderm of this region. The parieto-basilar muscle is diffuse and 

 feebly developed. The longitudinal muscle fibres are also very feeble, being 

 scarcely discernible. There is no special thickening of the endoderm in the lower 

 part of the mesenterial filaments as in Z. macgillivrayi. 



Gonads. — The sexes are distinct. We have sections of both male and female 

 specimens (PI. lxiv., figs. 3, 4). The gonads appear to be distributed on the 

 mesenteries in irregular rows. 



Zoanthus jukesii, n. sp. 

 (PI. LXi., figs. 3-5 ; PI. LXii., fig. 2 ; PI. lxiii., fig. 1.) 



Form. — Body short and thick ; body -wall smooth and delicate ; coenenchyme 

 forming stolons : tentacles in two cycles of about 20—24 in each. 



Colour. — Body and stolon translucent gray, the endoderm shining through 

 with a brown tint (owing to the presence of zooxanthelte) ; capitulum pink, with 

 24 dark lines ; disc brown, with, usually, pairs of pale lines (mesenteries) for 

 inner cycle of tentacles ; mouth with greenish lip ; oesophagus gray. Tentacles : 

 inner cycle green, with dark rings or marks on the oral aspect; outer cycle opaque 

 pale pink ; all the tentacles with a dark spot at the tip ; the base of the tentacles 

 of the outer cycle is in some specimens tinged with green. 



