236 HYALONEMA (HYALONEMA) GRANDANCORA. 



large and small inicramphidiscs. The large macramphidiscs and the small 

 micramphidiscs are abundant, the others rare. A few amphidiscs 170-230 ii 

 long, with serrated teeth, have also been found in the spicule-preparations. 

 Since, however, these spicules are very rare and were not observed in the 

 sections, I take them to be foreign. 



All parts of the individual polyps and the bark-like coenenchym of the 

 Palythoa are protected by an armour which extends, in the inner dermal layer 

 of the stomatodeum of the polyps, far down into their gastral cavities. This 

 armour consists entirely of siliceous spicules identical with, or at least very 

 similar to, the acanthophores of the sponge. In the Palythoa armour the 

 acanthophores with only terminally spined rays form a small minority, the 

 majority being entirely spined (Plate 78, fig. 20). 



The dermal pinules (Plate 78, figs. 41, 44, 45; Plate 79, fig. 20) of the upper 

 and middle-parts of the outer surface are pentactine. The distal ray is 240-293 n 

 long, and 7-10 ijl thick at the base. Its proximal and distal end-parts are smooth. 

 The latter appears as a rather long and slender terminal cone. The remaining 

 part of the ray bears spines of medium size which are generally slightly curved, 

 and concave towards the shaft. The maximum thickness of the distal ray, 

 together with the spines, is 17-26 fi. The lateral rays are 25-45 ^ long, conical, 

 and less rapidly attenuated towards the end in their proximal than in their distal 

 part. They are smooth in their proximal part; their distal and middle-parts 

 bear sparse, low, and broad spines. 



The dermal pinules on the basal part of the sponge are similar but have 

 distal rays only 190-260 /i long. 



The pinules in the walls of the large efferent canals (Plate 78, figs. 32, 43), 

 which may be considered as gastral or canalar, are nearly all pentactines, only 

 very few are hexactines. The distal ray is 250-395 m long, and 4-8 m thick at 

 the base. Its basal part is smooth for a considerable length, and the ray-ends 

 in a slender and sharp-pointed terminal cone. The spines on its middle-part are 

 rather small; its maximum thickness, together with the spines, is 11-23 /i. The 

 lateral rays are conical, slightly spined, and 43-72 yu long. One of the few 

 hexactine pinules, which I measured, had a proximal ray 50 ju long. 



The (hypodermal and hypogastral) pentactines have straight conical rays. 

 The proximal ray is 0.4-0.7 mm. long and 22-70 fi thick at the base. The 

 lateral rays are straight, 0.2-1.2 mm. long, and generally just perceptibly inclined 

 towards the shaft, so that the inner contour of any two opposite rays lies in a 

 straight line vertical to the axis of the shaft. 



