ON SOME JAPANESE CALCAREOUS SPONGES. 15 



oval or circular osciilum, surromided by a more or less distinctly 

 developed fringe of oxea. The specimen from Jôgashima is a 

 fragment of oscular tube with base. The last two specimens re- 

 present a colony of several small and tubular individuals joined 

 together at their base (PL I., fig. 5), 



To base further description on I have selected one of the 

 Döketsba specimens (Sei. Coll. Spec. No. 6 ; PI. I., fig. 4). It mea- 

 sures about GO mm. in total length and 11mm. in greatest width. 

 The wall reaches about 1 mm. in thickness. The osculum is oval, 

 measuring 2J by 5 mm. It leads into a wide and deep gastral 

 cavity. The sponge is bent in the basal parts, whe^e it presents a 

 somewhat irregular contour and also gives rise to some tubercular 

 processes for attachment. The dermal surface looks very smooth, 

 while the gastral is somewhat rough owing to projecting apical 

 rays of gastral quadriradiates. Colour in alcohol greyish white. 

 Texture firm, but elastic. 



Canal system (PI. n., fig. 13). 



The canal system is typically syconoid. The inhalant canals 

 open on the dermal surface by means of small irregularly round- 

 ish, mesh-like pores of 70-100 ,« diameter. The canals, after tra- 

 versing the dermal cortex, unite into larger trunks which lead into 

 the interstices between flagellate chambers. The dermal cortex, 

 which appears finely hispid on account of vertically disposed micr- 

 oxea, is rather thin, being about 100 // thick ; it directly overhes 

 the distal ends of flagellate chambers. The flagellate chambers 

 are elongate and radially arranged in the chamber layer. They 

 are usually simple, but are sometimes divided into two or three 

 parallel and distally narrowing branches. The chambers communi- 

 cate either singly or several together with exhalant canals, which 



