202 HYALONEMA (HYALONEMA) P()LYCAULUM. 



opposite flat face of the sponge the superficial tissue is, in four places, consider- 

 ably harder than elsewhere. These harder patches protrude more or less and 

 appear as superficial knobs. They are distant from each other and rather uni- 

 formly distributed over the face opposite the gastral. From two of these knobs 

 a few broken stalk-spicules protrude. 



The colour in spirit is brown. 



Skeleton. Of the dermal pinule-fur only insignificant remnants are left; the 

 gastral pinule-fur, however, is preserved in places. The dermal pinnies have 

 much shorter lateral rays than the gastral. Here and there, where the super- 

 ficial parts of the sponge are still present, pentactine megascleres occur. The 

 hard superficial knobs contain dense masses of tetractine (tetractine-derivate) 

 stout, and diactine (diactine-derivate) more slender acanthophores. Here also 

 slender-rayed, long-spined acanthophores are met. Large quantities of micro- 

 hexactines, some microhexactine-derivates with fewer than six rays, and a good 

 number of more or less pinule-like pentactines, which may be tubular pinules, 

 and amphidiscs occur in the choanosome rhabd and hexactine megascleres. 

 Certainly from two, probably from all the four hard superficial knobs bundles of 

 rather large spicules, broken off at the surface of the sponge, extend towards the 

 interior. One of these bundles leads up to the gastral cone above referred to. 

 The spiculation of these knobs indicates that certainly from two and probably 

 from all four there arise in life stalks composed of bundles of spicules. 



A good many anatriaenes with long and slender anchors, very large dicho- 

 triaenes, and large spiny metasters, aU foreign, and apparently belonging to some 

 species of Thenea, are found in the sponge. A few hexactinellid anchor- 

 spicules, similar to those of the holascids, were observed in the hard superficial 

 knobs. These spicules are 9-14 // thick, and have terminal tyles about 30 m in 

 diameter, beset with short anchor-teeth. I consider these spicules as foreign. 



The dermal pinules (Plate 54, figs. 35, 38-40) are generally pentactine, 

 very rarely hexactine. The distal ray is 110-130 fi long, and 4.5-9 m thick at 

 the base. It is straight, thickened above only very slightly or not at all, and 

 ends with a slender and sharp-pointed terminal cone, only about 4 n thick at the 

 base, that is at the point of insertion of the uppermost spines. The basal part 

 and the terminal cone of the distal ray are smooth, its middle-part bears sparse 

 spines. The lowest spines are short, arise steeply, and are usually slightly 

 inclined towards the tip of the ray. Sometimes they are more strongly inclined 

 in this direction, sometimes vertical, and sometimes even inclined towards the 

 base. Distally the spines at first increase in size, and then again become smaller. 



