76 ART. 7. — I. IJIMA : HEXACTINELLIDA, IV. 



The largest incurreut apertures, seen here and there in scattered 

 distribution, do not exceed 2 mm. in diameter. 



Spiculation. 



The pai^enchymalia seem to consist exclusively of diactins. 

 Not a single parenchymal hexactin could be discovered although 

 a special search was made for them. A number of the diactins 

 may be called princijmlia. These are straight or bow-shaped 

 spicules of varying strength ; smooth all over and sharply pointed 

 at ends. In the body proper they may measure ü mm. in length 

 and 275 /t in thickness in the middle ; in the stalk they are 

 generally longer but more slender, reaching up to 15 mm. in 

 length and 100 /j. in thickness. The larger diactins are found in 

 especial abundance near the external surface in both the body 

 and the stalk. In the latter they mostly run in longitudinal 

 directions. 



But by fc\r the greater part of the parenchymalia is made 

 up of very much finer diactins (accessoria) generally not over 

 o mm. in length with a breadth of only 4-15 //. The ends of 

 these are somewliat swollen, rounded and rough-surfaced. These 

 filamentous diiictins occur in part as comitalia to the stronger 

 spicules ; for the rest they stand alone by themselves and may 

 be developed in such exceedingly great numbers as to form a 

 tissue of very fine soft texture. Such a tissue exists even in the 

 stalk but is confined to the inner portion of its upper part. 

 When freed of any such coarser spicules as may be contained in 

 it, which can be done without much difficulty l)y feeling for 

 them, the tissue can be l)alled like wool or cotton by rolling it 

 between the fingers. 



