ART. 12 



HEXACTINELLID SPONGES — OKADA 



95 



the middle part of the spicule. There are frequently much slen- 

 derer, curved diactins, forming small bundles close together. At any 

 rate the parenchymal diactins are somewhat slender in form and are 



FiGDUB 12. — Acanthascus pacliyderma, new species : a, Gastral hexactin, X 225 ; h, 

 dermal stauractin, x 1,875; c, hexactinic form, X 225; d, oxyhexaster, X 375; e, 

 oxyhexaster (form A), X 375; /, oxyhexaster (form B), X 375; g-i, discoctasters, 

 X 375 ; i-l, basalia, X 225 



distributed much more irregularly and sparsely than those of the 

 hypogastral layer. 



Hypodermal diactins are loosely arranged and do not form strands, 

 as do those occurring in the hypogastral layer. They are wider but 



