AULOSACCÜS. 107 



in this way can be explained such oxyhexaster forms as are 

 shown in PI. YIII., figs. 12 and 13, or those I have seen in 

 which less than six (e. g., only four) rays in all emanated from 

 the central node. 



In all the oxyhexasters the terminals are rough-surfaced. 

 The roughness is frequently seen to be caused by minute retro- 

 verted tubercles. 



The precise extent of the short axial filaments forming the 

 central cross can be clearly observed if one goes through the 

 necessary steps of preparation. It needs simply to be stated that 

 PI. XIV., figs. 24 and 25, may be said to represent exactly the 

 state of things in the central part of oxyhexasters of the present 

 species. 



The discohexasters (PI. VIII. , figs. 10 & 11) are common 

 in both the choauosome and the gastral layer. At j^laces they 

 are much more numerous than the oxyhexasters. They occur in 

 one small and delicate form of spherical shape, measuring only 

 30-38 /^- in diameter. Each short principal bears sometimes about 

 10, and sometimes only about 6, very slender terminals ending 

 in a comparatively large disc with about half a dozen, slender, 

 marginal teeth. 



AULOSACCÜS IjiMA. 

 Aulosaccus, Ijima, 'g6. 

 Calycosaccus, F. E. Schulze, 'gg. 



Vase-like, thick-walled, firmly attached at base; 

 moderately large. Gastral surface lined with a conti- 



