20 



radial ray is on an average 150 « long, in the proximal third smooth, uni- 

 formly attenuated towards the sharp-pointed end and covered with rather short, 

 shghtly divergent spines in the distal two-thirds. The spines attain the greatest 

 length at the lower end of the distal spined part of the ray, upwards they gradu- 

 ally decrease in size (pi- XVII f. 6). The canalar pinules are very similar only 

 a little shorter, not more than 120 a^ long, and more slender. They occupy the 

 walls of the larger excurrent canals but do not stand nearly so close together as 

 the dermal pinules on the external surface (pi. XVII, f . 7.) The gastral pinules 

 are considerably longer, 350 /* and more long, but otherwise similar. They are 

 mostly oxypentactine, rarely oxyhexactine, and stand in great numbers close to- 

 gether on the strands of the gastral network on the terminal face of the sponge, 

 causing the velvety appearance mentioned above (pi. XVII, f. 8). 



The oxydiactine marginalia of the rounded oscular margin bear short spines 

 on their distal free part. They are in the material at my disposal so much in- 

 jured, however, that I cannot give an exact description of them. 



Macramphidiscs are not met with in the dermal membrane itself but are 

 fairly numerous just below it and in the internal parenchyme, where they appear 

 to be irregulai'ly scattered. They attain a considerable size, 600 h and more, 

 some of them however are much smaller, less than half as long. The shaft is 

 either sinooth or covered with irregularly distributed, sharp tubercles. It is not 

 cylindrical, the central part being considerably thinner than the gradually thick- 

 ened terminal parts. The terminal discs are 120 /^ long, hemispherical, and 

 have 8 marginal teeth of inconsiderable breadth, which terminate with lancet- 

 shaped points (pi. XVII, f. 13). 



Mesamphidiscs 50-60 j" long, chiefly occur between the basal crosses of the 

 canalar pentactine pinules, where they are pretty numerous. Their shaft is 

 cylindrical, of medium thickness, and covered with irregularly scattered sharp 

 tubercles ; sometimes there is a well defined central inflation. The terminal 

 discs are more or less deeply bell-shaped and usually have 10 narrow and pointed 

 marginal teeth which extend nearly parallel to the shaft (pi. XVIT, f. 9, 10). 



Micramphidiscs are found together with the mesamphidiscs, in the dermal 

 and gastral membranes and sometimes also in the parenchyme. Their number 

 is very variable. They have the usual shape, their terminal discs are hemi- 

 spherical and have 10-12 marginal teeth. They are generally only 20 i" long 

 but may attain a greater size and longer teeth, thus appearing connected with 

 the mesamphidiscs by transitions (pi. XVII, f. 12). 



In the lower, attenuated end of the body a few acanthophores are met with. 

 They have 2-6 stoat and usually slightly-curved rays; stauractines are most 

 numerous. Usually only the free, slightly-thickened terminal parts of the rays 

 are spined, the other parts remaining smooth. 



