AULOSACCUS SCHULZEI. 115 



ingly large and of a shape which may l)e called suu-like. From 

 a central spherical mass there arise like rays from all over its 

 surface numerous very long and slender terminals. This most 

 remarkable rosette is of moderately common occurrence in the 

 choauosome and can easily be recognized under the hand- lens as 

 it lies on or among the extracted parenchymalin, appearing like 

 a whitish fleck. The terminals always appear to have been more 

 or less disturbed in their positions ; they often stick together and 

 form indefinite bundles (PL VIII., fig. 27), apparently as the 

 result of mechanical strains upon their flexibility. If left per- 

 fectly undisturbed, we may assume that they would radiate uni- 

 formly in all directions, thus giving an approximately spherical 

 shape to the entire spicule. The diameter should then measure 

 nearly or quite 1 mm., a size which may be said to be gigantic 

 for a hexaster. As first sight one may be inclined to take the 

 spicule for some object other than a, hexaster. Nevertheless, 

 there can be no doubt whatever as to its hexaster-nature. 



The central sphere (PI. VIII., fig. 28) measures 46-49 // in 

 diameter. The surface is not even but shows some irregularity 

 in contour ; however, this does not in the slightest degree indi- 

 cate the convexity of the terminal surface of the six principals. 

 These, together with the original central node, seem to be com- 

 pletely imbedded in the sphere. In other words, apparently a 

 secondary deposition of siliceous matter has taken place between 

 and over the principals so as to fill up the interspaces between 

 them, also covering them up on the external surface between the 

 bases of the terminals. To become convinced of this point it is 

 necessary to examine the spicule in glycerine after it has been 

 thoroughly cleansed by boiling in acid. Under a high power of 

 the microscope, the six-armed cross of axial threads is then 



