24 AET. 5. — SANJI HÖZAWA : 



Prof. MiTSUKüRi at Koajiro, close to the Misaki Marine Biological 

 Station. The tubes measure 3-5 mm. in breadth, and the wall 

 1 mm. in thickness. The size of oscula is various, ranging from 

 J-2 mm. in diameter. They lead into the common gastral cavity 

 of a habitus corresponding to that of the entire specimen. The 

 colour in alcohol is greyish white. The texture is rigid. 



Canal system (PI. n., fig. 15). 



The canal system is sy conoid, though not in a very typical 

 way. The dermal cortex is very strongly developed. The dermal 

 pores are circular and small, measuring about 60 /^ across on an 

 average. 



The flagellate chambers, which are radially arranged around 

 the gastral cavity, extend through the greater part of the thick- 

 ness of wall. They are rather narrow, not quite straight, but 

 more or less crooked ; most of them branch once or twice in the 

 distal parts. The position of nucleus in collar cells is apical. 



The gastral cortex is much thinner than the dermal. It forms 

 a continuous lacework, the angular meshes (150-300 jj- across) of 

 which are visible to the naked eye. The meshes referred to con- 

 stitute the openings of exhalant canals into the gastral cavity. 

 The exhalant canals, arising from a single or more flagellate 

 chambers, are short. 



Skeleton (PL H., fig. 15). 



The fairly thick dermal skeleton is made up of : 1) sub- 

 regular or slightly sagittal triradiates, lying tangentially in several 

 layers in a rather confuse arrangement ; 2) the paired rays of 

 subdermal pseudosagittal triradiates ; and 3) small oxea grouped 

 into small tufts which project from the sponge surface. 



