148 AKT. 7. 1. IJIMA : HEXACÏINELLIDA, IV. 



Challenger Keport, wliicli preparation was of great service to me 

 in insuring a correct identification of specimens in the early 

 stage of mv studies. 



Principal parenchymalia, elongate spindle-like, sometimes 

 bow-like. Length, up to lomm.; thickness at middle, up to 300 

 ft. Thier pointed ends smooth, but sometimes rough as in all the 

 smaller parenchymalia. There exists a gradational series of vari- 

 ously sized parenchymalia, from the principalia down to comitalia 

 of only 6/^ thickness. (Fig. 36, PL XII., is intended to illustrate 

 the different modes of termination of the parenchymal diactins. 

 Unfortunately the representation of the subterminal roughness in 

 the thinner spicules has turned out to be a failure). 



The 2^^'ostalia are diactins of great length, which may measure 

 up to 25 mm. or more. They are probably to be looked at simply 

 in the light of excessivel}^ elongated parenchymal principalia. Like 

 these, the part imbedded within the sponge- wall is accompanied 

 by filamentous comitalia as well as by other loosely and radially 

 arranged parenchymalia whose outer ends are directed towards 

 the apex of the cones. 



The hypodennal and liypogadrcd strands consist of diactins, 

 and of diactins only, which aie arranged in loose or compact 

 bundles of variable strength (PI. XIL, figs. 34 and 35). The 

 elements look much like parenchymalia of similar dimensions. 

 They are gerierally not longer than 3 mm. nor broader than 38 

 !'■ in the middle. Towards both ends they gradually taper, the 

 very tip being either simply acuminate or conically pointed. 

 iSubterminally, the surface is roughened by microtubercles which 



