ART. 12 



HEXACTINELLID SPONGES OKADA 



23 



It frequently has a clearly defined central inflation, which usually 

 bears two knobs arranged on each side. The size of the oxydiactin 

 is fairly variable, generally 0.5 mm to 1.5 mm long and 20/a to 25/a 

 thick. 



Oxyhexactins occur much less frequently. Their rays are nearly 

 the same length, smooth, 30;^ thick, and gradually attenuated toward 



Figure 2. — Hyalonema (Cyliconema) hozawai, new species: a. Distal part of 

 dlactinic marginalia ; b, proximal part of diactinic marginalia ; o, dermal 

 pinule ; d, gastral pinule ; e, acanthophore ; f, acanthopliorc ; g, macramplii- 

 disk ; h, mesamphidisli ; i, young macramphidislc in basal regions ; ;, micraui- 

 phidisk ; h, microxyhexactin ; I, microstauractin ; m, micropentactin. All 

 X 250 



the pointed end. The paratangential rays are sometimes curved, 

 measuring 50/* to 600/a long. The distal ray is 610/i, long and the 

 proximal ray 680/i, and usually straight. 



In the subdermal oxypentactins, which form an important part 

 of the supporting skeleton, the paratangential basal rays are con- 



