HYALONEMA (OONEMA) CRASSIPINULUM. 
333 
which are the dermal, are continuous and fairly smooth. The upper surface, 
which is the gastral, now appears rugose. In life wide cavities, separated by 
upright walls, probably occupied the upper part of the interior. Reticulate 
pore-sieves are observed on some parts of the surface. Indications of flagel- 
late chambers about 140 ju in diameter were noticed in some of the sections. 
The colour in spirit is light dirty brown. 
A small colony of Palythoa polyps is attached to the upper part of the 
stalk. 
The skeleton. A fur composed of distal rays of large pinules covers the 
whole sponge. The gastral pinules, particularly those on the pore-sieves, are 
very large, the dermal considerably smaller. Very numerous large micramphi- 
discs lie in and on the surface. Microhexact.ines, paratangentially extending 
amphioxes, and the lateral rays of pentactines occur just below the lateral rays 
of the superficial pinules. Some hexactine and abundant rhabd megascleres, 
very numerous microhexactines, a few monactine microhexactine-derivates, 
canalar pinules, and amphidiscs are found in the interior. The internal amphi- 
discs are of four kinds: — 1, very scarce large macramphidiscs; 2, not numer- 
ous small broad-anchored macramphidiscs; 3, very scarce small macramphi- 
discs; and 4, very numerous micramphidiscs. It is possible, but not probable, 
that 1 and 3 are foreign spicules. Numerous acanthophores for the most part 
diactine and tetractine occur in the basal part of the sponge-body. The canalar 
pinules are rare, and found only here and there in the canal-walls. In the walls 
of some of the canals masses of micramphidiscs are observed. The remnant 
of the stalk consists of a few stout and several slender spicules. 
In the superficial part of the coenenchym and in the lateral and oral walls 
of the individual polyps of the Palythoa, spicules occur in large numbers; these 
are similar to the smaller and stouter acanthophores of the basal part of the 
sponge. 
The gastral superficial pinules have a distal ray 250-1130 n long (measured 
in the case of the curved ones along their chord). The length frequency-curve 
of the distal ray has two distinct elevations, at about GOO and 850 ^ . This 
indicates that two kinds of gastral pinules, a large and a small, should be dis- 
tinguished. 
The large gastral pinules (Plate 92 , figs. 1-4, 20, 22, 23), which greatly 
preponderate in the reticulate pore-sieves, are all pentactine. Their distal ray 
is straight or, comparatively very frequently, curved in its distal part. The 
curvature is usually not great but sometimes very marked. In one of these 
