ABT. 12 



HEXACTINELLID SPOXGES — OKADA 



27 



slender, straight, or sometimes slightly curved, and 1.7 mm to 2.5 mm 

 or more long, terminating with a somewhat expanded roughened 

 point at either end. Beside these, are frequently found the shorter 

 oxA^diactins, quite smooth on the surface, with two or four central 

 well-defined jDrotuberances in the middle, and measuring 1.2 mm to 

 2 mm in length and 20fi broad at the center. 



Between these spicules, sparsely scattered smooth oxyhexactins of 

 varying size, 1 mm to 1.2 mm in axial length, are found. The para- 



a c 



Figure 3. — Hyalonema (Coscinonema) ovatum, new species: a. Dermal pinule; 

 6, canalar pinule ; c, macramphidisk ; d, micramphidisk ; e, raesamphidisk ; f, 

 oxyhexactin ; g, oxyhexactin. All X 300 



tangential and distal rays are usually shorter than the proximal ray, 

 and all the rays measure 28/a broad at the base, being gradually at- 

 tenuated toward the pointed ends. 



The oxypentactins appear as regularly arranged hypodermalia, 

 lying below the outer surface and supporting the dermal membrane. 

 Under the gastral membrane there are probably no such spicules. In 

 these spicules the paratangential rays are mostly shorter than the 

 proximal unpaired ray, measuring 200/i to 850/t in length, while the 



