280 I. IJIMA : HEXACTINELLTDA. I. 



Okinos^ I have a specimen consisting of two individuals whose 

 stems had come in contact crosswise and had fused together. 

 Tliese cases may indicate that the species grow close together side 

 by side in certain localities. 



The species has as yet never been obtained in the Sagami 

 Bay, north of the Okinose ridge. 



General Characteks. 



The three specimens shown in PI. XII, reduced to '/^ natural 

 size, will give a good idea of the general appearance of the 

 sponge. It resembles in a measure a Cryptomeria or a fir-tree 

 denuded of leaves. The body may be said to consist of the basal 

 disc, the stem and the lateral branches. 



The basal disc is large, solid and compact. It may measure 

 120 mm. or more in diameter and about 3 mm. in thickness at 

 the blunt-edo'ed maroin. The thickness increases towards the 

 origin of the stem. The disc may be irregularly shaped con- 

 forming itself to the character of the rocky substratum. 



On the superior surface there are usually seen in small 

 numbers and in indefinite positions thin and sharp edged openings, 

 which may be as large as the oscula on the stem but usually are 

 smaller. They lead into shallow cavities, the wall of which 

 may again show perforations penetrating for some distance into 

 the hard basal mass. These are evidently excurrent canals, the 

 external openings being undoubtedly oscula. This leads us to 

 assume that the flagellated chambers occur even in the disc and 

 that the circulation of water takes place here in a manner similar. 



