94 AKT. T. 1. IJIMA : HEXACTINELLIDA, IV. 



all the principals bear two or more terminals each, were not met 

 with ; if at all present, they must be exceedingly rare. In dia- 

 meter or axial length, the oxyhexasters measure 100-145 //. 

 Hexactinose forms (axial length 120-145 ix) are for the most 

 part appreciably larger than those which are hemihexactinose ; 

 indeed this seems to be the general rule with all the Kossellids 

 in which oxyhexasters show a tendency to take the hexactinose 

 form. The terminals appear to Ije moderately strong, on an 

 average are about 2i thick at base, and are generally nearly 

 straight. Their surface is obsoletely rough. The principals are 

 exceedingly short, being almost reduced to nothing. In all cases 

 of the rosettes, if recourse be taken to proper methods of treat- 

 ment, the axial filament is seen to extend from the spicular center 

 into each principal but never beyond into the terminal, whether 

 this be sinsfle or double. 



In the hemihexactinose forms, it seems most usual that only 

 one or two, but sometimes three, of the six principals bear two 

 widely divergent terminals on each, the rest of the ])rincipals 

 being uniterminal. Thus, oxyhexasters with seven or eight ter- 

 minal points in all are of the most frequent occurrence. Some with 

 as many as 'nine terminal points in all have occasionally been met 

 with. A case of a principal bearing more than two terminals 

 has not been observed. This is in unison with the aj^parently 

 strong tendency of the oxyhexasters towards becoming hemihexact- 

 inose or hexactinose, for a biterminal principal may be said to 

 be in a stage which l)y l)ut one last step in the process of reduc- 

 tion would lead to a uniterminal state. The simple ray composed 

 of a principal and a single ray, whether belonging to a hemi- 

 hexactinose or to a hexactinose oxyhexaster, is usually nearly 

 straight throughout but may not infrequently show a gentle and 



