22 



vicinity of the upper end of the spicule-bundles which form the peduncle, spicules 

 of this kind, without central inflation or protuberances, are met with, one or both 

 ends of which are thickened and clubshaped (pi. XVIII, f. 13, 14). 



In all parts of the parenchjme microsclere oxy-hexactines about 100 m in 

 diameter are abundant. Their rays are either quite smooth or only very slightly 

 roughened, of medium stoutness, gradually attenuated from the centre to the 

 sharp-pointed end, and very distinctly and uniformly bent in their distal half 

 (pi. XVIII. f. 11). In the vicinity of the folded chamber-layer, that is in the 

 walls of both the incurrent and excurrent canals adjacent to it, only these 

 oxy-hexactines occur. 



In the membranes lining the larger canals further on, canalar pentactine- 

 pinules are met with. Nearest to the chamber-layer, these are small, slender, 

 and rather scarce, away from it they become stouter, longer, and more numerous. 

 The dermal reticulation is also densely covered with pentactine-piuules, the straight 

 and slightly-tuberculous basal rays of which are of medium thickness, gradually 

 attenuated towards the sharp-pointed end and 40-50 i^ long. Occasionally hex- 

 actine-pinules, with a shorter or longer inner ray, are found among them. The 

 distal ray is on an average 200 /^ long, not particularly stout, pointed, and 

 covered in the usual way with rather short spines. 



It is very remarkable tliat straight diactine pinules, pointed at both ends, 

 occur in considerable numbers between the ordinary pinules. These are 500-600 

 /^ long, their free distal ray is covered with very oblique pretty anliegenden 

 spines, and 300-400 /" long ; their inner, proximal, ray is much shorter, and smooth 

 or slightly tuberculous towards its pointed end. From the centre of the spicule 

 four rounded protuberances, arranged crosswise, arise (pi. XVIII, f. 10). These 

 spicules resemble in every respect the oxydiactine marginalia of other Hyalo- 

 nema-species. 



It is of great interest that the whole upper, terminal face is covered with 

 such marginalia-like oxydiactine pinules. Here they are longer (1000-1500 H- ) 

 and stand much closer together than in the dermal reticulation of the lateral 

 surface. Gastral pentactine pinules, similar to the dermal pentactine pinules, but 

 a little longer (200-300 /* : pi. XVIII. f. 9) are found between them in small num- 

 bers. The dense masses of oxydiactine pinules covering the terminal face ren- 

 der its appearance velvet-like. 



Amphidiscs of each of the three kinds are numerous, the macramphidiscs 

 being represented by two essentially different varieties. In the parenchyme irre- 

 gularly scattered macramphidiscs of the first variety, 500-1000 ^ long are fairly 

 abundant. The shaft is generally smooth, sometimes it bears scattered spines 

 and in the centre a whorl of 4-8 small, sharp tubercles : it is attenuated in the 

 middle and gradually thickened towards the ends. The terminal discs are hemi- 

 sperical, broader than high, and 120-100 H- in transverse diameter : they have 8 



