700 Reports on the Zoological Collections made in Torres Straits, 1888—1889. 



Parazoanthus douglasi, n. sp. 



(PL Lxi., figs. 16-22 ; PI. Lxii., fig. 6.) 



Form. — Body when growing on liydroids often somewhat long and relatively 

 narrow, but when growing on a flat surface, usually short and thick ; capitular 

 ridges not well marked ; texture gritty ; coenenchyme incrusting. 



Colour. — Sand colour. 



Dimensions. — Height variable; largest specimens 8—9 mm. ; diameter, 2-2'5 mm. 

 The shorter specimens growing on flat surfaces are from 3—5 mm. in height, and 

 2 mm. in diameter. 



Locality. — Albany Pass, Cape York. 10 fathoms. August 29, 1888. Numerous 

 specimens. 



[I have named this species in honour of the Hon. John Douglas, K.C.M.G., 

 Government Resident at Thursday Island, Torres Straits, who assisted me as far 

 as was in his power during my stay in Torres Straits. — A. C. H] 



Bocly-ivall. — As in P. dichroicus, but little ectoderm remains on the body- wall of 

 our specimens of P. douglasi, and that which does remain is continuous and covered 

 by a very delicate cuticle. The incrustations, which penetrate the greater part of 

 the thickness of the mesogloea, consist chiefly of sponge spicules (some of them being 

 triradiate) with a few grains of sand, foraminifera, &c., amongst them. There 

 is an encircling sinus which contains a few dark granules similar to those which 

 are so abundant in P. dichroicus, but it is for the most part almost empty. It is 

 crossed at intervals by the strands of mesogloea, and is connected with a system of 

 branching canals, which run outwards through the incrustation. Cell-islets, though 

 present, are not at all so numerous as in P. dichroicus. The endoderm forms a thin 

 layer of uniform thickness. The muscular layer is feebly developed. 



Capitulum. — The incrustations in this region are almost entirely confined to 

 sponge spicules. The ridges, although not externally conspicuous, can be well 

 seen in our transverse sections. 



Sphincter muscle. — The spincter muscle is entirely endodermal. The mesogloeal 

 plaitings are regular and simple. 



Disc and tentacles — The structure of disc and tentacles is very similar to that 

 of P. dichroicus, but there appear to be no enclosures of any kind in the mesogloea. 

 (Esophagus. — The ectoderm of tlie oesophagus is thrown into slight folds. There 

 is a distinct groove, the mesogloea being much thickened in this region. 



Mesenteries. — The arrangement of the mesenteries is brachycnemic. The imj)er- 

 fect mesenteries are even more feebly developed than in P. dichroicus, being in 

 many cases hardly discernible. The mesogloea forms a fairly thick layer. 



