236 
HYALONEMA (HYALONEMA) GRANDANCORA. 
large and small micramphidiscs. The large macramphi discs and the small 
micramphidiscs are abundant, the others rare. A few amphidiscs 170-230 n 
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 gast.ral 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 
acant.hophores with only terminally spined rays form a small minority, the 
majority being entirely spined (Plate 78 , fig. 20). 
The dermal pinnies (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 m 
long, and 7-10 n 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 i±. The lateral rays are 25-45 p. 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 m long. 
The pinules in the walls of the large efferent canals (Plate 78 , figs. 32, 43), 
which may be considered as gast.ral or canalar, are nearly all pentactines, only 
very few are hexactines. The distal ray is 250-395 n 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 id. The 
lateral rays are conical, slightly spined, and 43-72 ^ long. One of the few 
hexactine pinules, which I measured, had a proximal ray 50 ^ long. 
The (hypodermal and hypogastral) pe?itactines have straight conical rays. 
The proximal ray is 0.4-0. 7 mm. long and 22-70 /x 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. 
