90 ART. 1. 1. IJIMA : HEXACTINELLIDA, III. 



of the excurrent canal-system. " There certainly does not exist any 

 direct connexion between it and the gastral siir&ce. 



The texture of tissues in the sponge-body is markedly soft 

 and delicate, which is due to the fineness of all the spicules. 



Spiculation. 



The parenchymalia consist mainly of diactins, intermixed 

 with which are however a not inconsiderable quantity of regular 

 hexactius. 



The diactins run either isolated or in loose or compact 

 bundles. They are all short and thin, seldom exceeding 2 mm. in 

 length and 15/^ in breadth. The spicular center is usually plain, 

 only occasionally supplied with an annular swelling. The breadth 

 generally remains nearly the same in the greater part of the rays. 

 The terminal roughened portion is often slightly swollen before 

 ending in a rounded or a conical point. In the compact wall of 

 the stalk, the diactins, in the main longitudinally disposed, are 

 generally somewhat longer and frequently as thick as 35/^. Here 

 the rough ends are often swollen in a knob-like manner. There 

 is nothing in the synapticular formations in the stalk requiring 

 particular mention. 



The parenchymal hexactins have straight smooth rays, whi(;h 

 gradually taper towards the sharply or bluntly oi- conically pointed, 

 slightly rough-surfaced end. In these charactei's they agree 

 well with both the hypodermal and the hypogastral pentactins ; 

 so also in dimensions in the generality of cases, but sometimes 

 they are considerably larger and stronger (figs. 18 & 21). The 

 axial length may reach 1,6 mm. 



