ON SOME JAPANESE CALCAREOUS SPONGES. 17 



very closely set triradiates, which have very strongly diverging 

 paired rays. 



Spicules. 



Dermal triradiates (textfig. 3, a, b). — ^SKghtly sagittal. Basal 

 ray straight, smooth, gradually and sharply pointed, 120-250/^ 

 long and 16-20/^ thick. Paired rays very slightly curved and 

 gradually sharp-pointed. They are nearly as thick as the basal 

 ray, but shorter, being 80-190/^ long and 12-16/^ thick. 



Subdermal triradiates (textfig. 3, c, d). — Pseudosagittal, irregu- 

 lar. Basal ray considerably longer than the paired rays, shghtly 

 bent near base, and gradually sharp-pointed, 280-360 ,« long and 

 16-20 ft thick. Paired rays equally thick but differing in length 

 and shape. The longer ray gently curved and gradually sharp- 

 pointed, 80-130 /i long and 12-16 /^ thick. The shorter ray more or 

 less angularly curved in the middle, gradually and sharply pointed, 

 50-120// long and 12-16// thick. 



Tubar triradiates (textfig. 3, <?,/, ^, Ä). — Sagittal. Basal ray 

 straight, gradually sharp-pointed, much longer and slightly thicker 

 than the paired rays, 120-380/« long and 12-16// thick. Paired 

 rays are of equal or shghtly differentiated length, gi-adually sharp - 

 pointed, straight or slightly bent, 60-120 /« long and 8-12 // thick. 



Subgastral triradiates (textfig. 3, i). — Sagittal. Similar to 

 tubar triradiates, but the paired rays are more strongly divergent. 

 AU rays lie in the same plane. Basal ray straight, much longer 

 and shghtly thicker than the paired rays, 250-330 // long and 16- 

 20 // thick. Paired rays shghtly curved, gradually and sharply 

 pointed, 100-160// long and 12-16// thick. 



Gastral triradiates (textfig. 3,y, k, I). — Eegular or very 

 shghtly sagittal. AU rays gi^adually and sharply pointed, generaUy 



