212 ART. 7. 1. IJIMA : HEXACTIA'ELLIDA, IV. 



of various thicknesses but on the whole are thin. They run in 

 somewhat curved courses and intersect with their fellows at 

 various angles, thus forming meshes of very irregular shapes. 

 Frequently a number of the strands are seen to radiate, though 

 in an irregular manner, from the point where a pillar or pillars 

 from the choanosme join the ectosome. 



The endosome appears much like the ectosome. It lies 

 closely applied to the internal choanosomal surface. The gastralia 

 form a continuous lacework over the meshes bounded l)y the hypo- 

 2;astral strands which are on the whole somewhat thicker than 

 the hypodermal. 



Characteristic of all the specimens are the rather cavernous 

 appearance, and the somewhat loose and light-looking texture, of the 

 wall. The former character is due to the spacious development of 

 the subdermal cavity and to the comparatively large caliljer of the 

 canals proceeding from it. The subdermal cavity is of a width 

 known to me in no other Acanthascine species. In large specimens 

 it may in some places be nearly 10 mm. wide. Conical or irregu- 

 larly ridge-like projections — the pillars — ^^join the choanosome to 

 the ectosome. The spaces between such adjacent pillars vary in ex- 

 tent and may each contain sometimes a single and sometimes several 

 large incurrent canalar apertures. These are round or oval, measur- 

 ing up to about 7 mm. dia. in large individuals, and may be 

 separated from one another by an interspace of 4 mm. or more. 



The incurrent canals are not deep and pit-like, but rather 

 shallow and funnel-shaped. This is probably in some way related 

 to the wide development of the subdermal space, which not in- 

 fre(][ueutly passes over into the canals without any ^perceptible 

 demarcation. The apertures of branch canals opening into the 

 primary canals are generally plainly visible from the outside. 



