FIOURK 24. .1C. HK 23. 



->:i. AII.OSIMI \|.;n\ I:I.I:C.ANTISSIMA (AITI:U 11 UXKKK). IIKTAII. or 

 mUCTTTUC. 



iir.riii: Jl. AI I.<H KHOS (Arm HAECXXB). IIKTAIL SKC'TION OK SIMNK. 



a.. Lumen of shaft, ak., axial canal, h., vesicular enlargement of 



secondary silicification. in., 



axial canal 

 membrane, 



at forking of spiiu-. 



377 



