69 



thickened and abruptly truncate. The branch-rays are about 35 h- long, smooth, 

 straight or Rightly bent outward at the base, and gradually attenuated towards 

 the sharp-pointed end. They arise from the margin of the terminal faces of the 

 truncate main-rays. Unlike the branch-rays of most hexasters the branch-rays 

 of these oxystaurasters do not diverge from the main-ray under equal angles. 

 The branch-rays, which lie in or near the plane of the main-rays, do not diverge 

 nearly so much as the others. The angle between the former and the continua- 

 tion of the main-ray is about 45°, whilst the other branch-rays often stand nearly 

 vertical to the main-ray. By thus so strongly diverging these rays evidently 

 endeavour, as it were, to replace the two missing main-rays of the ideal hexaster. 



The sword-shaped oxyhexactine hypodermalia are generally stouter than the 

 parenchymal oxyhexactines. Their distal, radial ray attains a length of 120 ^ 

 and is terminally closely covered with very small tubercles. Bach of the four 

 similar paratangential rays is about 200 and the proximal, radial ray about 400 /» 

 long. 



In the subdermal region bundles of slender, straight rhaphids over 100 /^ 

 in length occur. The presence of these and of regularly hexaradiates consisting 

 of six slender rays with terminal discs, to the outer surfaces of which stumps of 

 broken branch-rays are attached, prove that graphiocoms occur in this sponge. 

 Occasionally I also found an intact graphiocom. 



The fioricoms present in the different genera of Euplectellidx and also in 

 Begadrella, are in this species rather small ; they measure only 72-80 t^ in diame- 

 ter. Their main-rays are cylindrical, about 10 t^ long and bear a calyx-like, 

 terminal verticil of 7-9 S-shaped branch-rays, the discs at the end of which 

 have only 3, more rarely 5 or 2, marginal teeth (claws). 



The gastral membrane is supported by pentactine hypogastralia the size of 

 which differs in the different regions of the body. The four tangential rays 

 measure 200 ^ and more in length and are terminally thickened, club-shaped. 

 They are smooth at the base and in the middle but tuberculous in their terminal, 

 thickened part. The radial, distal ray is similar, but considerably longer. In 

 place of the missing sixth, proximal ray a simple tubercle, or button-shaped 

 protuberance, is generally met with. 



In the annular membranes surrounding the parietal apertures stout, rough, 

 tuberculous or even spined hexactines and pentactines with rays only 100-150 /^ 

 long occur. The spined rays measure at the base 8-20 h- and more in thickness. 



Although only a few small fragments of this sponge are at my disposal it is, 

 on account of the similarity of the spicules, chiefly the peculiar oxystaurasters, 

 hardly to be doubted that it is closely allied to, if not identical with Ijima's 

 Japanese Regadrelhi ohinoseana. The most important differences between the 

 two are the following : Jjima states that, in his species hexasters occur together 



